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Wang LT, Cooper AJR, Farrell B, Miura K, Diouf A, Müller-Sienerth N, Crosnier C, Purser L, Kirtley PJ, Maciuszek M, Barrett JR, McHugh K, Ogwang R, Tucker C, Li S, Doumbo S, Doumtabe D, Pyo CW, Skinner J, Nielsen CM, Silk SE, Kayentao K, Ongoiba A, Zhao M, Nguyen DC, Lee FEH, Minassian AM, Geraghty DE, Traore B, Seder RA, Wilder BK, Crompton PD, Wright GJ, Long CA, Draper SJ, Higgins MK, Tan J. Natural malaria infection elicits rare but potent neutralizing antibodies to the blood-stage antigen RH5. Cell 2024; 187:4981-4995.e14. [PMID: 39059381 PMCID: PMC11383431 DOI: 10.1016/j.cell.2024.06.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 04/15/2024] [Accepted: 06/26/2024] [Indexed: 07/28/2024]
Abstract
Plasmodium falciparum reticulocyte-binding protein homolog 5 (RH5) is the most advanced blood-stage malaria vaccine candidate and is being evaluated for efficacy in endemic regions, emphasizing the need to study the underlying antibody response to RH5 during natural infection, which could augment or counteract responses to vaccination. Here, we found that RH5-reactive B cells were rare, and circulating immunoglobulin G (IgG) responses to RH5 were short-lived in malaria-exposed Malian individuals, despite repeated infections over multiple years. RH5-specific monoclonal antibodies isolated from eight malaria-exposed individuals mostly targeted non-neutralizing epitopes, in contrast to antibodies isolated from five RH5-vaccinated, malaria-naive UK individuals. However, MAD8-151 and MAD8-502, isolated from two malaria-exposed Malian individuals, were among the most potent neutralizers out of 186 antibodies from both cohorts and targeted the same epitopes as the most potent vaccine-induced antibodies. These results suggest that natural malaria infection may boost RH5-vaccine-induced responses and provide a clear strategy for the development of next-generation RH5 vaccines.
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Affiliation(s)
- Lawrence T Wang
- Antibody Biology Unit, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA; Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA; Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK; Medical Scientist Training Program, University of California, San Diego School of Medicine, La Jolla, CA 92093, USA
| | - Andrew J R Cooper
- Antibody Biology Unit, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Brendan Farrell
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford OX1 3QU, UK
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Ababacar Diouf
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | | | - Cécile Crosnier
- Department of Biology, Hull York Medical School, York Biomedical Research Institute, University of York, Heslington, York YO10 5DD, UK
| | - Lauren Purser
- Antibody Biology Unit, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Payton J Kirtley
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Portland, OR 97006, USA
| | - Maciej Maciuszek
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Jordan R Barrett
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford OX1 3QU, UK
| | - Kirsty McHugh
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford OX1 3QU, UK
| | - Rodney Ogwang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Courtney Tucker
- Antibody Biology Unit, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Shanping Li
- Malaria Infection Biology and Immunity Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Safiatou Doumbo
- Mali International Center of Excellence in Research, University of Sciences, Technique and Technology of Bamako, Point G, BP 1805 Bamako, Mali
| | - Didier Doumtabe
- Mali International Center of Excellence in Research, University of Sciences, Technique and Technology of Bamako, Point G, BP 1805 Bamako, Mali
| | - Chul-Woo Pyo
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Jeff Skinner
- Malaria Infection Biology and Immunity Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Carolyn M Nielsen
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford OX1 3QU, UK
| | - Sarah E Silk
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford OX1 3QU, UK
| | - Kassoum Kayentao
- Mali International Center of Excellence in Research, University of Sciences, Technique and Technology of Bamako, Point G, BP 1805 Bamako, Mali
| | - Aissata Ongoiba
- Mali International Center of Excellence in Research, University of Sciences, Technique and Technology of Bamako, Point G, BP 1805 Bamako, Mali
| | - Ming Zhao
- Protein Chemistry Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Doan C Nguyen
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Emory University, Atlanta, GA 30322, USA
| | - F Eun-Hyung Lee
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Emory University, Atlanta, GA 30322, USA
| | - Angela M Minassian
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford OX1 3QU, UK; NIHR Oxford Biomedical Research Centre, Oxford OX3 9DU, UK
| | - Daniel E Geraghty
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Boubacar Traore
- Mali International Center of Excellence in Research, University of Sciences, Technique and Technology of Bamako, Point G, BP 1805 Bamako, Mali
| | - Robert A Seder
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Brandon K Wilder
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Portland, OR 97006, USA
| | - Peter D Crompton
- Malaria Infection Biology and Immunity Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Gavin J Wright
- Department of Biology, Hull York Medical School, York Biomedical Research Institute, University of York, Heslington, York YO10 5DD, UK
| | - Carole A Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Simon J Draper
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford OX1 3QU, UK; NIHR Oxford Biomedical Research Centre, Oxford OX3 9DU, UK
| | - Matthew K Higgins
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot Hodgkin Building, South Parks Road, Oxford OX1 3QU, UK
| | - Joshua Tan
- Antibody Biology Unit, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
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2
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Barrett JR, Pipini D, Wright ND, Cooper AJR, Gorini G, Quinkert D, Lias AM, Davies H, Rigby CA, Aleshnick M, Williams BG, Bradshaw WJ, Paterson NG, Martinson T, Kirtley P, Picard L, Wiggins CD, Donnellan FR, King LDW, Wang LT, Popplewell JF, Silk SE, de Ruiter Swain J, Skinner K, Kotraiah V, Noe AR, MacGill RS, King CR, Birkett AJ, Soisson LA, Minassian AM, Lauffenburger DA, Miura K, Long CA, Wilder BK, Koekemoer L, Tan J, Nielsen CM, McHugh K, Draper SJ. Analysis of the diverse antigenic landscape of the malaria protein RH5 identifies a potent vaccine-induced human public antibody clonotype. Cell 2024; 187:4964-4980.e21. [PMID: 39059380 PMCID: PMC11380582 DOI: 10.1016/j.cell.2024.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 04/14/2024] [Accepted: 06/10/2024] [Indexed: 07/28/2024]
Abstract
The highly conserved and essential Plasmodium falciparum reticulocyte-binding protein homolog 5 (PfRH5) has emerged as the leading target for vaccines against the disease-causing blood stage of malaria. However, the features of the human vaccine-induced antibody response that confer highly potent inhibition of malaria parasite invasion into red blood cells are not well defined. Here, we characterize 236 human IgG monoclonal antibodies, derived from 15 donors, induced by the most advanced PfRH5 vaccine. We define the antigenic landscape of this molecule and establish that epitope specificity, antibody association rate, and intra-PfRH5 antibody interactions are key determinants of functional anti-parasitic potency. In addition, we identify a germline IgG gene combination that results in an exceptionally potent class of antibody and demonstrate its prophylactic potential to protect against P. falciparum parasite challenge in vivo. This comprehensive dataset provides a framework to guide rational design of next-generation vaccines and prophylactic antibodies to protect against blood-stage malaria.
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Affiliation(s)
- Jordan R Barrett
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Dimitra Pipini
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Nathan D Wright
- Centre for Medicines Discovery, University of Oxford, Oxford OX3 7FZ, UK
| | - Andrew J R Cooper
- Antibody Biology Unit, Laboratory of Immunogenetics, NIAID/NIH, Rockville, MD 20852, USA
| | - Giacomo Gorini
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Doris Quinkert
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Amelia M Lias
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Hannah Davies
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Cassandra A Rigby
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK
| | - Maya Aleshnick
- Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, OR 97006, USA
| | - Barnabas G Williams
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - William J Bradshaw
- Centre for Medicines Discovery, University of Oxford, Oxford OX3 7FZ, UK
| | - Neil G Paterson
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Thomas Martinson
- Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, OR 97006, USA
| | - Payton Kirtley
- Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, OR 97006, USA
| | - Luc Picard
- Department of Biological Engineering, MIT, Cambridge, MA, USA
| | | | - Francesca R Donnellan
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Lloyd D W King
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Lawrence T Wang
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; Antibody Biology Unit, Laboratory of Immunogenetics, NIAID/NIH, Rockville, MD 20852, USA
| | | | - Sarah E Silk
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Jed de Ruiter Swain
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Katherine Skinner
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | | | - Amy R Noe
- Leidos Life Sciences, Frederick, MD, USA
| | - Randall S MacGill
- Center for Vaccine Innovation and Access, PATH, Washington, DC 20001, USA
| | - C Richter King
- Center for Vaccine Innovation and Access, PATH, Washington, DC 20001, USA
| | - Ashley J Birkett
- Center for Vaccine Innovation and Access, PATH, Washington, DC 20001, USA
| | | | - Angela M Minassian
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK
| | | | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, NIAID/NIH, Rockville, MD 20852, USA
| | - Carole A Long
- Laboratory of Malaria and Vector Research, NIAID/NIH, Rockville, MD 20852, USA
| | - Brandon K Wilder
- Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, OR 97006, USA
| | - Lizbé Koekemoer
- Centre for Medicines Discovery, University of Oxford, Oxford OX3 7FZ, UK
| | - Joshua Tan
- Antibody Biology Unit, Laboratory of Immunogenetics, NIAID/NIH, Rockville, MD 20852, USA
| | - Carolyn M Nielsen
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Kirsty McHugh
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK
| | - Simon J Draper
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK; The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK.
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Diawara H, Healy SA, Mwakingwe-Omari A, Issiaka D, Diallo A, Traore S, Soumbounou IH, Gaoussou S, Zaidi I, Mahamar A, Attaher O, Fried M, Wylie BJ, Mohan R, Doan V, Doritchamou JYA, Dolo A, Morrison RD, Wang J, Hu Z, Rausch KM, Zeguime A, Murshedkar T, Kc N, Sim BKL, Billingsley PF, Richie TL, Hoffman SL, Dicko A, Duffy PE. Safety and efficacy of PfSPZ Vaccine against malaria in healthy adults and women anticipating pregnancy in Mali: two randomised, double-blind, placebo-controlled, phase 1 and 2 trials. THE LANCET. INFECTIOUS DISEASES 2024:S1473-3099(24)00360-8. [PMID: 39153490 DOI: 10.1016/s1473-3099(24)00360-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/07/2024] [Accepted: 05/30/2024] [Indexed: 08/19/2024]
Abstract
BACKGROUND Plasmodium falciparum parasitaemia during pregnancy causes maternal, fetal, and infant mortality. Poor pregnancy outcomes are related to blood-stage parasite sequestration and the ensuing inflammatory response in the placenta, which decreases over successive pregnancies. A radiation-attenuated, non-replicating, whole-organism vaccine based on P falciparum sporozoites (PfSPZ Vaccine) has shown efficacy at preventing infection in African adults. Here, we aimed to examine vaccine safety and efficacy of the PfSPZ Vaccine in adults and women who anticipated conception. METHODS Two randomised, double-blind, placebo-controlled trials (phase 1 MLSPZV3 and phase 2 MLSPZV4) were conducted at a clinical research centre in Mali. MLSPZV3 included adults aged 18-35 years and MLSPZV4 included non-pregnant women aged 18-38 years who anticipated conception within a year of enrolment. In MLSPZV3, participants were stratified by village and randomly assigned (2:1) using block randomisation to receive three doses of 9 × 105 PfSPZ Vaccine or saline placebo at weeks 0, 1, and 4 (4-week schedule) or at weeks 0, 8, and 16 (16-week schedule) and a booster dose around 1 year later. In MLSPZV4, women received presumptive artemether-lumefantrine twice per day for 3 days 2 weeks before dose one and were randomly assigned (1:1:1) using block randomisation to receive three doses of 9 × 105 or 1·8 × 106 PfSPZ Vaccine or saline placebo all administered at weeks 0, 1, and 4 (4-week schedule). Participants in both studies received artemether-lumefantrine 2 weeks before dose three and additionally 2 weeks before dose four (booster dose) in MLSPZV3. Investigators and participants were masked to group assignment. The primary outcome, assessed in the as-treated population, was PfSPZ Vaccine safety and tolerability within 7 days after each dose. The secondary outcome, assessed in the modified intention-to-treat population, was vaccine efficacy against P falciparum parasitaemia (defined as the time-to-first positive blood smear) from dose three until the end of transmission season. In exploratory analyses, MLSPZV4 evaluated incidence of maternal obstetric and neonatal outcomes as safety outcomes, and vaccine efficacy against P falciparum parasitaemia during pregnancy (defined as time-to-first positive blood smear post-conception). In MLSPZV4, women were followed at least once a month with human chorionic gonadotropin testing, and those who became pregnant received standard of care (including intermittent presumptive sulfadoxine-pyrimethamine antimalarial drugs after the first trimester) during routine antenatal visits. These studies are registered with ClinicalTrials.gov, NCT03510481 and NCT03989102. FINDINGS Participants were enrolled for vaccination during the onset of malaria seasons for two sequential studies conducted from 2018 to 2019 for MLSPZV3 and from 2019 to 2021 for MLSPZV4, with follow-up during malaria seasons across 2 years. In MLSPZV3, 478 adults were assessed for eligibility, of whom 220 were enrolled between May 30 and June 12, 2018, and then between Aug 13 and Aug 18, 2018, and 210 received dose one. 66 (96%) of 69 participants who received the 16-week schedule and 68 (97%) of 70 who received the 4-week schedule of the 9 × 105 PfSPZ Vaccine and 70 (99%) of 71 who received saline completed all three doses in year 1. In MLSPZV4, 407 women were assessed for eligibility, of whom 324 were enrolled from July 3 to July 27, 2019, and 320 received dose one of presumptive artemether-lumefantrine. 300 women were randomly assigned with 100 per group (PfSPZ Vaccine 9 × 105, 1·8 × 106, or saline) receiving dose one. First trimester miscarriages were the most commonly reported serious adverse event but occurred at a similar rate across study groups (eight [15%] of 54 with 9 × 105 PfSPZ Vaccine, 12 [21%] of 58 with 1·8 × 106 PfSPZ Vaccine, and five [12%] of 43 with saline). One unrelated maternal death occurred 425 days after the last vaccine dose in the 1·8 × 106 PfSPZ Vaccine group due to peritonitis shortly after childbirth. Most related adverse events reported in MLSPZV3 and MLSPZV4 were mild (grade 1) and frequency of adverse events in the PfSPZ Vaccine groups did not differ from that in the saline group. Two unrelated serious adverse events occurred in MLSPZV3 (one participant had appendicitis in the 9 × 105 PfSPZ Vaccine group and the other in the saline group died due to a road traffic accident). In MLSPZV3, the 9 × 105 PfSPZ Vaccine did not show vaccine efficacy against parasitaemia with the 4-week (27% [95% CI -18 to 55] in year 1 and 42% [-5 to 68] in year 2) and 16-week schedules (16% [-34 to 48] in year 1 and -14% [-95 to 33] in year 2); efficacies were similar or worse against clinical malaria compared with saline. In MLSPZV4, the PfSPZ Vaccine showed significant efficacy against parasitaemia at doses 9 × 105 (41% [15 to 59]; p=0·0069 in year 1 and 61% [36 to 77]; p=0·0011 in year 2) and 1·8 × 106 (54% [34 to 69]; p<0·0001 in year 1 and 45% [13 to 65]; p=0·029 in year 2); and against clinical malaria at doses 9 × 105 (47% [20 to 65]; p=0·0045 in year 1 and 56% [22 to 75]; p=0·0081 in year 2) and 1·8 × 106 (48% [22 to 65]; p=0·0013 in year 1 and 40% [2 to 64]; p=0·069 in year 2). Vaccine efficacy against post-conception P falciparum parasitaemia during first pregnancies that arose in the 2-year follow-up was 57% (14 to 78; p=0·017) in the 9 × 105 PfSPZ Vaccine group versus 49% (3 to 73; p=0·042) in the 1·8 × 106 PfSPZ Vaccine group. Among 55 women who became pregnant within 24 weeks after dose three, vaccine efficacy against parasitaemia was 65% (23 to 84; p=0·0088) with the 9 × 105 PfSPZ Vaccine and 86% (64 to 94; p<0·0001) with the 1·8 × 106 PfSPZ Vaccine. When combined in a post-hoc analysis, women in the PfSPZ Vaccine groups had a non-significantly reduced time-to-first pregnancy after dose one compared with those in the saline group (log-rank test p=0·056). Exploratory maternal obstetric and neonatal outcomes did not differ significantly between vaccine groups and saline. INTERPRETATION PfSPZ Vaccine was safe and well tolerated in adults in Mali. The 9 × 105 and 1·8 × 106 doses of PfSPZ Vaccine administered as per the 4-week schedule, which incorporated presumptive antimalarial treatment before the first vaccine dose, showed significant efficacy against P falciparum parasitaemia and clinical malaria for two malaria transmission seasons in women of childbearing age and against pregnancy malaria. PfSPZ Vaccine without presumptive antimalarial treatment before the first vaccine dose did not show efficacy. FUNDING National Institute of Allergy and Infectious Diseases, National Institutes of Health, and Sanaria.
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Affiliation(s)
- Halimatou Diawara
- Malaria Research and Training Center, University of Sciences, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Sara A Healy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Agnes Mwakingwe-Omari
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Djibrilla Issiaka
- Malaria Research and Training Center, University of Sciences, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Aye Diallo
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Seydou Traore
- Malaria Research and Training Center, University of Sciences, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Ibrahim H Soumbounou
- Malaria Research and Training Center, University of Sciences, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Santara Gaoussou
- Malaria Research and Training Center, University of Sciences, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Irfan Zaidi
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Almahamoudou Mahamar
- Malaria Research and Training Center, University of Sciences, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Oumar Attaher
- Malaria Research and Training Center, University of Sciences, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Michal Fried
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Blair J Wylie
- Columbia University Medical Center, Columbia University, New York, NY, USA
| | - Rathy Mohan
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Viyada Doan
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Justin Y A Doritchamou
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Amagana Dolo
- Malaria Research and Training Center, University of Sciences, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Robert D Morrison
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jing Wang
- Clinical Monitoring Research Program Directorate, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Zonghui Hu
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Kelly M Rausch
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Amatigue Zeguime
- Malaria Research and Training Center, University of Sciences, Techniques, and Technologies of Bamako, Bamako, Mali
| | | | | | | | | | | | | | - Alassane Dicko
- Malaria Research and Training Center, University of Sciences, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
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4
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Goswami D, Patel H, Betz W, Armstrong J, Camargo N, Patil A, Chakravarty S, Murphy SC, Sim BKL, Vaughan AM, Hoffman SL, Kappe SH. A replication competent Plasmodium falciparum parasite completely attenuated by dual gene deletion. EMBO Mol Med 2024; 16:723-754. [PMID: 38514791 PMCID: PMC11018819 DOI: 10.1038/s44321-024-00057-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 03/06/2024] [Accepted: 03/07/2024] [Indexed: 03/23/2024] Open
Abstract
Vaccination with infectious Plasmodium falciparum (Pf) sporozoites (SPZ) administered with antimalarial drugs (PfSPZ-CVac), confers superior sterilizing protection against infection when compared to vaccination with replication-deficient, radiation-attenuated PfSPZ. However, the requirement for drug administration constitutes a major limitation for PfSPZ-CVac. To obviate this limitation, we generated late liver stage-arresting replication competent (LARC) parasites by deletion of the Mei2 and LINUP genes (mei2-/linup- or LARC2). We show that Plasmodium yoelii (Py) LARC2 sporozoites did not cause breakthrough blood stage infections and engendered durable sterilizing immunity against various infectious sporozoite challenges in diverse strains of mice. We next genetically engineered a PfLARC2 parasite strain that was devoid of extraneous DNA and produced cryopreserved PfSPZ-LARC2. PfSPZ-LARC2 liver stages replicated robustly in liver-humanized mice but displayed severe defects in late liver stage differentiation and did not form liver stage merozoites. This resulted in complete abrogation of parasite transition to viable blood stage infection. Therefore, PfSPZ-LARC2 is the next-generation vaccine strain expected to unite the safety profile of radiation-attenuated PfSPZ with the superior protective efficacy of PfSPZ-CVac.
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Affiliation(s)
- Debashree Goswami
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, WA, 98109, USA
| | - Hardik Patel
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, WA, 98109, USA
| | - William Betz
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, WA, 98109, USA
| | - Janna Armstrong
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, WA, 98109, USA
| | - Nelly Camargo
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, WA, 98109, USA
| | - Asha Patil
- Sanaria Inc., 9800 Medical Center Dr., Rockville, MD, 20850, USA
| | | | - Sean C Murphy
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - B Kim Lee Sim
- Sanaria Inc., 9800 Medical Center Dr., Rockville, MD, 20850, USA
| | - Ashley M Vaughan
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, WA, 98109, USA
- Department of Pediatrics, University of Washington, Seattle, WA, USA
| | | | - Stefan Hi Kappe
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, WA, 98109, USA.
- Department of Pediatrics, University of Washington, Seattle, WA, USA.
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5
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Nguyen TK, Jun H, Louis JM, Mazigo E, Lee WJ, Youm HC, Shin J, Lungu DK, Kanyemba C, Ahmed MA, Muh F, Lee SJ, Na S, Chun W, Park WS, No JH, Kim MJ, Han ET, Han JH. Enhancing malaria detection in resource-limited areas: A high-performance colorimetric LAMP assay for Plasmodium falciparum screening. PLoS One 2024; 19:e0298087. [PMID: 38335219 PMCID: PMC10857711 DOI: 10.1371/journal.pone.0298087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 01/17/2024] [Indexed: 02/12/2024] Open
Abstract
Malaria eradication efforts in resource-limited areas require a rapid, economical, and accurate tool for detecting of the low parasitemia. The malaria rapid diagnostic test (mRDT) is the most suitable for on-site detection of the deadliest form of malaria, Plasmodium falciparum. However, the deletions of histidine rich protein 2 and 3 genes are known to compromise the effectiveness of mRDT. One of the approaches that have been explored intensively for on-site diagnostics is the loop-mediated isothermal amplification (LAMP). LAMP is a one-step amplification that allows the detection of Plasmodium species in less than an hour. Thus, this study aims to present a new primer set to enhance the performance of a colorimetric LAMP (cLAMP) for field application. The primer binding regions were selected within the A-type of P. falciparum 18S rRNA genes, which presents a dual gene locus in the genome. The test result of the newly designed primer indicates that the optimal reaction condition for cLAMP was 30 minutes incubation at 65°C, a shorter incubation time compared to previous LAMP detection methods that typically takes 45 to 60 minutes. The limit of detection (LoD) for the cLAMP using our designed primers and laboratory-grown P. falciparum (3D7) was estimated to be 0.21 parasites/μL which was 1,000-fold higher than referencing primers. Under optimal reaction condition, the new primer sets showed the sensitivity (100%, 95% CI: 80.49-100%) and specificity (100%, 95% CI: 94.64-100%) with 100% (95% CI: 95.70-100%) accuracy on the detection of dried blood spots from Malawi (n = 84). Briefly, the newly designed primer set for P. falciparum detection exhibited high sensitivity and specificity compared to referenced primers. One great advantage of this tool is its ability to be detected by the naked eye, enhancing field approaches. Thus, this tool has the potential to be effective for accurate early parasite detection in resource-limited endemic areas.
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Affiliation(s)
- Tuyet Kha Nguyen
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Hojong Jun
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Johnsy Mary Louis
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Ernest Mazigo
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Wang-Jong Lee
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | | | - Jieun Shin
- Noul Co., Ltd., Yongin, Gyeonggi-do, Republic of Korea
| | | | | | - Md Atique Ahmed
- ICMR-Regional Medical Research Centre, NER, Dibrugarh, Assam, India
| | - Fauzi Muh
- Faculty of Public Health, Department of Epidemiology and Tropical Diseases, Universitas Diponegoro, Semarang, Indonesia
| | - Se Jin Lee
- Department of Obstetrics and Gynecology, Kangwon National University Hospital, Chuncheon, Gangwon-do, Republic of Korea
| | - Sunghun Na
- Department of Obstetrics and Gynecology, Kangwon National University Hospital, Chuncheon, Gangwon-do, Republic of Korea
| | - Wanjoo Chun
- Department of Pharmacology, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Won Sun Park
- Department of Physiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Joo Hwan No
- Host-Parasite Research Laboratory, Institut Pasteur Korea, Seongnam, Gyeonggi-do, Republic of Korea
| | - Min-Jae Kim
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Jin-Hee Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
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6
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Hergott DEB, Owalla TJ, Staubus WJ, Seilie AM, Chavtur C, Balkus JE, Apio B, Lema J, Cemeri B, Akileng A, Chang M, Egwang TG, Murphy SC. Assessing the daily natural history of asymptomatic Plasmodium infections in adults and older children in Katakwi, Uganda: a longitudinal cohort study. THE LANCET. MICROBE 2024; 5:e72-e80. [PMID: 38185134 PMCID: PMC10790327 DOI: 10.1016/s2666-5247(23)00262-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 08/13/2023] [Accepted: 08/16/2023] [Indexed: 01/09/2024]
Abstract
BACKGROUND Low-density asymptomatic Plasmodium infections are prevalent in endemic areas, but little is known about their natural history. The trajectories of these infections and their propensity to fluctuate to undetectable densities can affect detection in clinical trials and field studies. We aimed to classify the natural history of these infections in a high transmission area over 29 days. METHODS In this longitudinal cohort study, we enrolled healthy, malaria-asymptomatic, afebrile, adults (age 18-59 years) and older children (age 8-17 years) in Katakwi District, Uganda, who were negative for Plasmodium infection on rapid diagnostic tests. Participants were instructed to self-collect one dried blood spot (DBS) per day for a maximum of 29 days. We excluded people if they were pregnant or taking antimalarials. During weekly clinic visits, staff collected a DBS and a 4 mL sample of venous blood. We analysed DBSs by Plasmodium 18S rRNA quantitative RT-PCR (qRT-PCR). We classified DBS by infection type as negative, P falciparum, non-P falciparum, or mixed. We plotted infection type over time for each participant and categorised trajectories as negative, new, cleared, chronic, or indeterminate infections. To estimate the effect of single timepoint sampling, we calculated the daily prevalence for each study day and estimated the number of infections that would have been detected in our population if sampling frequency was reduced. FINDINGS Between April 9 and May 20, 2021, 3577 DBSs were collected by 128 (40 male adults, 60 female adults, 12 male children, and 16 female children) study participants. 2287 (64%) DBSs were categorised as negative, 751 (21%) as positive for P falciparum, 507 (14%) as positive for non-P falciparum, and 32 (1%) as mixed infections. Daily Plasmodium prevalence in the population ranged from 45·3% (95% CI 36·6-54·1) at baseline to 30·3% (21·9-38·6) on day 24. 37 (95%) of 39 P falciparum and 35 (85%) of 41 non-P falciparum infections would have been detected with every other day sampling, whereas, with weekly sampling, 35 (90%) P falciparum infections and 31 (76%) non-P falciparum infections would have been detected. INTERPRETATION Parasite dynamics and species are highly variable among low-density asymptomatic Plasmodium infections. Sampling every other day or every 3 days detected a similar proportion of infections as daily sampling, whereas testing once per week or even less frequently could misclassify up to a third of the infections. Even using highly sensitive diagnostics, single timepoint testing might misclassify the true infection status of an individual. FUNDING US National Institutes of Health and Bill and Melinda Gates Foundation.
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Affiliation(s)
- Dianna E B Hergott
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, USA
| | - Tonny J Owalla
- Department of Parasitology and Immunology, Med Biotech Laboratories, Kampala, Uganda
| | - Weston J Staubus
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Annette M Seilie
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Chris Chavtur
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Jennifer E Balkus
- Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, USA
| | - Bernadette Apio
- Department of Parasitology and Immunology, Med Biotech Laboratories, Kampala, Uganda
| | - Jimmy Lema
- Department of Parasitology and Immunology, Med Biotech Laboratories, Kampala, Uganda
| | - Barbara Cemeri
- Department of Parasitology and Immunology, Med Biotech Laboratories, Kampala, Uganda
| | - Andrew Akileng
- Department of Parasitology and Immunology, Med Biotech Laboratories, Kampala, Uganda
| | - Ming Chang
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Thomas G Egwang
- Department of Parasitology and Immunology, Med Biotech Laboratories, Kampala, Uganda
| | - Sean C Murphy
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA; Department of Microbiology, University of Washington, Seattle, WA, USA.
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7
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Shears MJ, Reynolds RA, Duncombe CJ, Watson FN, Staubus WJ, Chavtur C, Seilie AM, Tran TM, Chakravarty S, Hoffman SL, Murphy SC. Plasmodium knowlesi in pig-tailed macaques: a potential new model for malaria vaccine research. Malar J 2023; 22:379. [PMID: 38093306 PMCID: PMC10720125 DOI: 10.1186/s12936-023-04788-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/11/2023] [Indexed: 12/17/2023] Open
Abstract
BACKGROUND Plasmodium knowlesi is an established experimental model for basic and pre-clinical malaria vaccine research. Historically, rhesus macaques have been the most common host for malaria vaccine studies with P. knowlesi parasites. However, rhesus are not natural hosts for P. knowlesi, and there is interest in identifying alternative hosts for vaccine research. The study team previously reported that pig-tailed macaques (PTM), a natural host for P. knowlesi, could be challenged with cryopreserved P. knowlesi sporozoites (PkSPZ), with time to blood stage infection equivalent to in rhesus. Here, additional exploratory studies were performed to evaluate PTM as potential hosts for malaria vaccine studies. The aim was to further characterize the parasitological and veterinary health outcomes after PkSPZ challenge in this macaque species. METHODS Malaria-naïve PTM were intravenously challenged with 2.5 × 103 PkSPZ and monitored for blood stage infection by Plasmodium 18S rRNA RT-PCR and thin blood smears. Disease signs were evaluated by daily observations, complete blood counts, serum chemistry tests, and veterinary examinations. After anti-malarial drug treatment, a subset of animals was re-challenged and monitored as above. Whole blood gene expression analysis was performed on selected animals to assess host response to infection. RESULTS In naïve animals, the kinetics of P. knowlesi blood stage replication was reproducible, with parasite burden rising linearly during an initial acute phase of infection from 6 to 11 days post-challenge, before plateauing and transitioning into a chronic low-grade infection. After re-challenge, infections were again reproducible, but with lower blood stage parasite densities. Clinical signs of disease were absent or mild and anti-malarial treatment was not needed until the pre-defined study day. Whole blood gene expression analysis identified immunological changes associated with acute and chronic phases of infection, and further differences between initial challenge versus re-challenge. CONCLUSIONS The ability to challenge PTM with PkSPZ and achieve reliable blood stage infections indicate this model has significant potential for malaria vaccine studies. Blood stage P. knowlesi infection in PTM is characterized by low parasite burdens and a benign disease course, in contrast with the virulent P. knowlesi disease course commonly reported in rhesus macaques. These findings identify new opportunities for malaria vaccine research using this natural host-parasite combination.
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Affiliation(s)
- Melanie J Shears
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican Street, F870, Seattle, WA, 98109, USA
- Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, 750 Republican Street, Seattle, WA, 98109, USA
- Washington National Primate Research Center, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA
| | - Rebekah A Reynolds
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican Street, F870, Seattle, WA, 98109, USA
- Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, 750 Republican Street, Seattle, WA, 98109, USA
| | - Caroline J Duncombe
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican Street, F870, Seattle, WA, 98109, USA
- Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, 750 Republican Street, Seattle, WA, 98109, USA
| | - Felicia N Watson
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican Street, F870, Seattle, WA, 98109, USA
- Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, 750 Republican Street, Seattle, WA, 98109, USA
| | - Weston J Staubus
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican Street, F870, Seattle, WA, 98109, USA
- Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, 750 Republican Street, Seattle, WA, 98109, USA
| | - Chris Chavtur
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican Street, F870, Seattle, WA, 98109, USA
- Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, 750 Republican Street, Seattle, WA, 98109, USA
| | - Annette M Seilie
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican Street, F870, Seattle, WA, 98109, USA
- Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, 750 Republican Street, Seattle, WA, 98109, USA
| | - Tuan M Tran
- Division of Infectious Diseases, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Sumana Chakravarty
- Sanaria, Inc., 9800 Medical Center Drive, Suite A209, Rockville, MD, 20850, USA
| | - Stephen L Hoffman
- Sanaria, Inc., 9800 Medical Center Drive, Suite A209, Rockville, MD, 20850, USA
| | - Sean C Murphy
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican Street, F870, Seattle, WA, 98109, USA.
- Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, 750 Republican Street, Seattle, WA, 98109, USA.
- Washington National Primate Research Center, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA.
- Department of Microbiology, University of Washington, 750 Republican Street, F870, Seattle, WA, 98109, USA.
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Harl J, Himmel T, Ilgūnas M, Valkiūnas G, Weissenböck H. The 18S rRNA genes of Haemoproteus (Haemosporida, Apicomplexa) parasites from European songbirds with remarks on improved parasite diagnostics. Malar J 2023; 22:232. [PMID: 37563610 PMCID: PMC10416517 DOI: 10.1186/s12936-023-04661-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 07/27/2023] [Indexed: 08/12/2023] Open
Abstract
BACKGROUND The nuclear ribosomal RNA genes of Plasmodium parasites are assumed to evolve according to a birth-and-death model with new variants originating by duplication and others becoming deleted. For some Plasmodium species, it has been shown that distinct variants of the 18S rRNA genes are expressed differentially in vertebrate hosts and mosquito vectors. The central aim was to evaluate whether avian haemosporidian parasites of the genus Haemoproteus also have substantially distinct 18S variants, focusing on lineages belonging to the Haemoproteus majoris and Haemoproteus belopolskyi species groups. METHODS The almost complete 18S rRNA genes of 19 Haemoproteus lineages of the subgenus Parahaemoproteus, which are common in passeriform birds from the Palaearctic, were sequenced. The PCR products of 20 blood and tissue samples containing 19 parasite lineages were subjected to molecular cloning, and ten clones in mean were sequenced each. The sequence features were analysed and phylogenetic trees were calculated, including sequence data published previously from eight additional Parahaemoproteus lineages. The geographic and host distribution of all 27 lineages was visualised as CytB haplotype networks and pie charts. Based on the 18S sequence data, species-specific oligonucleotide probes were designed to target the parasites in host tissue by in situ hybridization assays. RESULTS Most Haemoproteus lineages had two or more variants of the 18S gene like many Plasmodium species, but the maximum distances between variants were generally lower. Moreover, unlike in most mammalian and avian Plasmodium species, the 18S sequences of all but one parasite lineage clustered into reciprocally monophyletic clades. Considerably distinct 18S clusters were only found in Haemoproteus tartakovskyi hSISKIN1 and Haemoproteus sp. hROFI1. The presence of chimeric 18S variants in some Haemoproteus lineages indicates that their ribosomal units rather evolve in a semi-concerted fashion than according to a strict model of birth-and-death evolution. CONCLUSIONS Parasites of the subgenus Parahaemoproteus contain distinct 18S variants, but the intraspecific variability is lower than in most mammalian and avian Plasmodium species. The new 18S data provides a basis for more thorough investigations on the development of Haemoproteus parasites in host tissue using in situ hybridization techniques targeting specific parasite lineages.
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Affiliation(s)
- Josef Harl
- Department of Pathobiology, Institute of Pathology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Tanja Himmel
- Department of Pathobiology, Institute of Pathology, University of Veterinary Medicine Vienna, Vienna, Austria
| | | | | | - Herbert Weissenböck
- Department of Pathobiology, Institute of Pathology, University of Veterinary Medicine Vienna, Vienna, Austria
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9
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Chavtur C, Staubus WJ, Ho M, Hergott DEB, Seilie AM, Healy S, Duffy P, Jackson L, Talley A, Kappe SHI, Hoffman SL, Richie TL, Kublin JG, Chang M, Murphy SC. Plasmodium 18S Ribosomal RNA Biomarker Clearance After Food and Drug Administration-Approved Antimalarial Treatment in Controlled Human Malaria Infection Trials. Open Forum Infect Dis 2023; 10:ofad202. [PMID: 37265668 PMCID: PMC10230565 DOI: 10.1093/ofid/ofad202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 04/12/2023] [Indexed: 06/03/2023] Open
Abstract
Background Sensitive molecular assays, such as quantitative reverse-transcription polymerase chain reaction (qRT-PCR) of Plasmodium 18S ribosomal RNA (rRNA), are increasingly the primary method of detecting infections in controlled human malaria infection (CHMI) trials. However, thick blood smears (TBSs) remain the main method for confirming clearance of parasites after curative treatment, in part owing to uncertainty regarding biomarker clearance rates. Methods For this analysis, 18S rRNA qRT-PCR data were compiled from 127 Plasmodium falciparum-infected participants treated with chloroquine or atovaquone-proguanil in 6 CHMI studies conducted in Seattle, Washington, over the past decade. A survival analysis approach was used to compare biomarker and TBS clearance times among studies. The effect of the parasite density at which treatment was initiated on clearance time was estimated using linear regression. Results The median time to biomarker clearance was 3 days (interquartile range, 3-5 days), while the median time to TBS clearance was 1 day (1-2 days). Time to biomarker clearance increased with the parasite density at which treatment was initiated. Parasite density did not have a significant effect on TBS clearance. Conclusions The Plasmodium 18S rRNA biomarker clears quickly and can be relied on to confirm the adequacy of Food and Drug Administration-approved treatments in CHMI studies at nonendemic sites.
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Affiliation(s)
- Chris Chavtur
- Malaria Molecular Diagnostic Laboratory, Department of Laboratory Medicine and Pathology and Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Weston J Staubus
- Malaria Molecular Diagnostic Laboratory, Department of Laboratory Medicine and Pathology and Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Mabel Ho
- Malaria Molecular Diagnostic Laboratory, Department of Laboratory Medicine and Pathology and Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Dianna E B Hergott
- Malaria Molecular Diagnostic Laboratory, Department of Laboratory Medicine and Pathology and Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, USA
- Department of Epidemiology, School of Public Health, University of Washington, Seattle, Washington, USA
| | - Annette M Seilie
- Malaria Molecular Diagnostic Laboratory, Department of Laboratory Medicine and Pathology and Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Sara Healy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Patrick Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Lisa Jackson
- Kaiser Permanente Washington Health Research Institute, Seattle, Washington, USA
| | | | - Stefan H I Kappe
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | | | | | - James G Kublin
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
- Seattle Malaria Clinical Trials Center, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Ming Chang
- Malaria Molecular Diagnostic Laboratory, Department of Laboratory Medicine and Pathology and Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Sean C Murphy
- Malaria Molecular Diagnostic Laboratory, Department of Laboratory Medicine and Pathology and Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, USA
- Seattle Malaria Clinical Trials Center, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
- Department of Microbiology, University of Washington, Seattle, Washington, USA
- Department of Laboratories, Seattle Children's Hospital, Seattle, Washington, USA
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Saeheng T, Na-Bangchang K. Prediction of improved antimalarial chemotherapy of artesunate-mefloquine in combination with mefloquine sensitive and resistant Plasmodium falciparum malaria. PLoS One 2023; 18:e0282099. [PMID: 36821622 PMCID: PMC9949628 DOI: 10.1371/journal.pone.0282099] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 02/07/2023] [Indexed: 02/24/2023] Open
Abstract
BACKGROUND Declining in susceptibility of Plasmodium falciparum to mefloquine is reported in South-East Asia. A revisiting on mefloquine pharmacokinetics-pharmacodynamics (PK/PD) could assist in finding new appropriate dosage regimens in combination with artesunate as a three-day course treatment. OBJECTIVE This study aimed to investigate promising alternative artesunate-mefloquine combination regimens that are effective for the treatment of patients with mefloquine-sensitive and resistant P. falciparum malaria. METHODS Data collected during 2008-2009 from 124 patients with uncomplicated P. falciparum malaria were included in the analysis, 90 and 34 patients with sensitive and recrudescence response, respectively. All patients were treated with a three-day combination of artesunate-mefloquine. Population PK-PD models were developed. The developed models were validated with clinically observed data. Simulations of clinical efficacy of alternative mefloquine regimens were performed based on mefloquine sensitivity, patients' adherence and parasite biomass. RESULTS The developed PK/PD models well described with clinically observed data. For mefloquine-resistant P. falciparum, a three-day standard regimen of artesunate-mefloquine is suitable (>50% efficacy) only when the level of parasite sensitivity was < 1.5-fold of the cut-off level (IC50 < 36 nM). For mefloquine-sensitive parasite with IC50 < 23.19 nM (0.96-fold), all regimens provided satisfactory efficacy. In the isolates with IC50 of 24 nM, regimen-I is recommended. Curative treatment criteria for mefloquine and artesunate were C336h (>408 ng.mL-1) or Cmax/IC50 (>130.1 g.m/M), and Cmax/IC50 (>381.2 g.m/M), respectively. CONCLUSIONS Clinical use of a three-day standard artesunate-mefloquine is suitable only when the IC50 of P. falciparum isolates is lower than 36 nM. Otherwise, other ACT regimens should be replaced. For mefloquine-sensitive parasite, a dose reduction is recommended with the IC50 is lower than 23.19 nM.
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Affiliation(s)
- Teerachat Saeheng
- Center of Excellence in Pharmacology and Molecular Biology of Malaria and Cholangiocarcinoma, Chulabhorn International College, Thammasat University (Rangsit Campus), Klongneung, Klongluang District, Pathumthani, Thailand
| | - Kesara Na-Bangchang
- Center of Excellence in Pharmacology and Molecular Biology of Malaria and Cholangiocarcinoma, Chulabhorn International College, Thammasat University (Rangsit Campus), Klongneung, Klongluang District, Pathumthani, Thailand
- Drug Discovery and Development Center, Office of Advanced Science and Technology, Thammasat University (Rangsit Campus), Klongneung, Klongluang District, Pathumthani, Thailand
- * E-mail:
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11
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Creation and preclinical evaluation of genetically attenuated malaria parasites arresting growth late in the liver. NPJ Vaccines 2022; 7:139. [PMCID: PMC9636417 DOI: 10.1038/s41541-022-00558-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 10/13/2022] [Indexed: 11/06/2022] Open
Abstract
AbstractWhole-sporozoite (WSp) malaria vaccines induce protective immune responses in animal malaria models and in humans. A recent clinical trial with a WSp vaccine comprising genetically attenuated parasites (GAP) which arrest growth early in the liver (PfSPZ-GA1), showed that GAPs can be safely administered to humans and immunogenicity is comparable to radiation-attenuated PfSPZ Vaccine. GAPs that arrest late in the liver stage (LA-GAP) have potential for increased potency as shown in rodent malaria models. Here we describe the generation of four putative P. falciparum LA-GAPs, generated by CRISPR/Cas9-mediated gene deletion. One out of four gene-deletion mutants produced sporozoites in sufficient numbers for further preclinical evaluation. This mutant, PfΔmei2, lacking the mei2-like RNA gene, showed late liver growth arrest in human liver-chimeric mice with human erythrocytes, absence of unwanted genetic alterations and sensitivity to antimalarial drugs. These features of PfΔmei2 make it a promising vaccine candidate, supporting further clinical evaluation. PfΔmei2 (GA2) has passed regulatory approval for safety and efficacy testing in humans based on the findings reported in this study.
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12
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Owalla TJ, Hergott DEB, Seilie AM, Staubus W, Chavtur C, Chang M, Kublin JG, Egwang TG, Murphy SC. Rethinking detection of pre-existing and intervening Plasmodium infections in malaria clinical trials. Front Immunol 2022; 13:1003452. [PMID: 36203582 PMCID: PMC9531235 DOI: 10.3389/fimmu.2022.1003452] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 08/22/2022] [Indexed: 02/02/2023] Open
Abstract
Pre-existing and intervening low-density Plasmodium infections complicate the conduct of malaria clinical trials. These infections confound infection detection endpoints, and their immunological effects may detract from intended vaccine-induced immune responses. Historically, these infections were often unrecognized since infrequent and often analytically insensitive parasitological testing was performed before and during trials. Molecular diagnostics now permits their detection, but investigators must weigh the cost, complexity, and personnel demands on the study and the laboratory when scheduling such tests. This paper discusses the effect of pre-existing and intervening, low-density Plasmodium infections on malaria vaccine trial endpoints and the current methods employed for their infection detection. We review detection techniques, that until recently, provided a dearth of cost-effective strategies for detecting low density infections. A recently deployed, field-tested, simple, and cost-effective molecular diagnostic strategy for detecting pre-existing and intervening Plasmodium infections from dried blood spots (DBS) in malaria-endemic settings is discussed to inform new clinical trial designs. Strategies that combine sensitive molecular diagnostic techniques with convenient DBS collections and cost-effective pooling strategies may enable more thorough and informative infection monitoring in upcoming malaria clinical trials and epidemiological studies.
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Affiliation(s)
- Tonny J. Owalla
- Department of Immunology and Parasitology, Med Biotech Laboratories, Kampala, Uganda
| | - Dianna E. B. Hergott
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States,Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, United States
| | - Annette M. Seilie
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States,Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, United States
| | - Weston Staubus
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States,Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, United States
| | - Chris Chavtur
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States,Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, United States
| | - Ming Chang
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States,Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, United States
| | - James G. Kublin
- Department of Global Health, University of Washington, Seattle, WA, United States,Seattle Malaria Clinical Trials Center, Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States
| | - Thomas G. Egwang
- Department of Immunology and Parasitology, Med Biotech Laboratories, Kampala, Uganda
| | - Sean C. Murphy
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States,Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, United States,Seattle Malaria Clinical Trials Center, Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States,Department of Microbiology, University of Washington, Seattle, WA, United States,*Correspondence: Sean C. Murphy,
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13
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Hu F, Ye X, Zhang LX. Multi-arm covariate-adaptive randomization. SCIENCE CHINA. MATHEMATICS 2022; 66:163-190. [PMID: 35912316 PMCID: PMC9326148 DOI: 10.1007/s11425-020-1954-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 02/21/2022] [Indexed: 06/15/2023]
Abstract
Simultaneously investigating multiple treatments in a single study achieves considerable efficiency in contrast to the traditional two-arm trials. Balancing treatment allocation for influential covariates has become increasingly important in today's clinical trials. The multi-arm covariate-adaptive randomized clinical trial is one of the most powerful tools to incorporate covariate information and multiple treatments in a single study. Pocock and Simon's procedure has been extended to the multi-arm case. However, the theoretical properties of multi-arm covariate-adaptive randomization have remained largely elusive for decades. In this paper, we propose a general framework for multi-arm covariate-adaptive designs which also includes the two-arm case, and establish the corresponding theory under widely satisfied conditions. The theoretical results provide new insights into the balance properties of covariate-adaptive randomization procedures and make foundations for most existing statistical inferences under two-arm covariate-adaptive randomization. Furthermore, these open a door to study the theoretical properties of statistical inferences for clinical trials based on multi-arm covariate-adaptive randomization procedures.
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Affiliation(s)
- Feifang Hu
- Department of Statistics, The George Washington University, Washington, DC, 20052 USA
| | - Xiaoqing Ye
- Institute of Statistics and Big Data, Renmin University of China, Beijing, 100872 China
| | - Li-Xin Zhang
- School of Mathematical Sciences, Zhejiang University, Hangzhou, 310058 China
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14
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Hergott DEB, Owalla TJ, Balkus JE, Apio B, Lema J, Cemeri B, Akileng A, Seilie AM, Chavtur C, Staubus W, Chang M, Egwang TG, Murphy SC. Feasibility of community at-home dried blood spot collection combined with pooled reverse transcription PCR as a viable and convenient method for malaria epidemiology studies. Malar J 2022; 21:221. [PMID: 35836179 PMCID: PMC9284728 DOI: 10.1186/s12936-022-04239-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/26/2022] [Indexed: 01/08/2023] Open
Abstract
Background Many Plasmodium infections in endemic regions exist at densities below the limit of detection of standard diagnostic tools. These infections threaten control efforts and may impact vaccine and therapeutic drug studies. Simple, cost-effective methods are needed to study the natural history of asymptomatic submicroscopic parasitaemia. Self-collected dried blood spots (DBS) analysed using pooled and individual quantitative reverse transcription polymerase chain reaction (qRT-PCR) provide such a solution. Here, the feasibility and acceptability of daily at-home DBS collections for qRT-PCR was studied to better understand low-density infections. Methods Rapid diagnostic test (RDT)-negative individuals in Katakwi District, northeastern Uganda, were recruited between April and May 2021. Venous blood samples and clinic-collected DBS were taken at enrollment and at four weekly clinic visits. Participants were trained in DBS collection and asked to collect six DBS weekly between clinic visits. Opinions about the collection process were solicited using daily Diary Cards and a Likert scale survey at the final study visit. Venous blood and DBS were analysed by Plasmodium 18S rRNA qRT-PCR. The number of participants completing the study, total DBS collected, and opinions of the process were analysed to determine compliance and acceptability. The human internal control mRNA and Plasmodium 18S rRNA were evaluated for at-home vs. clinic-collected DBS and venous blood to assess quality and accuracy of at-home collected samples. Results One-hundred two adults and 29 children were enrolled, and 95 and 26 completed the study, respectively. Three individuals withdrew due to pain or inconvenience of procedures. Overall, 96% of participants collected ≥ 16 of 24 at-home DBS, and 87% of DBS contained ≥ 40 µL of blood. The procedure was well tolerated and viewed favourably by participants. At-home collected DBS were acceptable for qRT-PCR and showed less than a one qRT-PCR cycle threshold shift in the human control mRNA compared to clinic-collected DBS. Correlation between Plasmodium falciparum 18S rRNA from paired whole blood and DBS was high (R = 0.93). Conclusions At-home DBS collection is a feasible, acceptable, and robust method to obtain blood to evaluate the natural history of low-density Plasmodium infections by qRT-PCR. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04239-x.
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Affiliation(s)
- Dianna E B Hergott
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA.,Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, USA
| | - Tonny J Owalla
- Med Biotech Laboratories, P.O. Box 9364, Kampala, Uganda
| | - Jennifer E Balkus
- Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, USA
| | | | - Jimmy Lema
- Med Biotech Laboratories, P.O. Box 9364, Kampala, Uganda
| | - Barbara Cemeri
- Med Biotech Laboratories, P.O. Box 9364, Kampala, Uganda
| | - Andrew Akileng
- Med Biotech Laboratories, P.O. Box 9364, Kampala, Uganda
| | - Annette M Seilie
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA.,Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Chris Chavtur
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA.,Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Weston Staubus
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA.,Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Ming Chang
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA.,Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | | | - Sean C Murphy
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA. .,Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, Seattle, WA, USA. .,Department of Microbiology, University of Washington, Seattle, WA, USA.
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15
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Wilder BK, Vigdorovich V, Carbonetti S, Minkah N, Hertoghs N, Raappana A, Cardamone H, Oliver BG, Trakhimets O, Kumar S, Dambrauskas N, Arredondo SA, Camargo N, Seilie AM, Murphy SC, Kappe SHI, Sather DN. Anti-TRAP/SSP2 monoclonal antibodies can inhibit sporozoite infection and may enhance protection of anti-CSP monoclonal antibodies. NPJ Vaccines 2022; 7:58. [PMID: 35618791 PMCID: PMC9135708 DOI: 10.1038/s41541-022-00480-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 04/22/2022] [Indexed: 11/10/2022] Open
Abstract
Vaccine-induced sterilizing protection from infection by Plasmodium parasites, the pathogens that cause malaria, will be essential in the fight against malaria as it would prevent both malaria-related disease and transmission. Stopping the relatively small number of parasites injected by the mosquito before they can migrate from the skin to the liver is an attractive means to this goal. Antibody-eliciting vaccines have been used to pursue this objective by targeting the major parasite surface protein present during this stage, the circumsporozoite protein (CSP). While CSP-based vaccines have recently had encouraging success in disease reduction, this was only achieved with extremely high antibody titers and appeared less effective for a complete block of infection (i.e., sterile protection). While such disease reduction is important, these and other results indicate that strategies focusing on CSP alone may not achieve the high levels of sterile protection needed for malaria eradication. Here, we show that monoclonal antibodies (mAbs) recognizing another sporozoite protein, TRAP/SSP2, exhibit a range of inhibitory activity and that these mAbs may augment CSP-based protection despite conferring no sterile protection on their own. Therefore, pursuing a multivalent subunit vaccine immunization is a promising strategy for improving infection-blocking malaria vaccines.
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Affiliation(s)
- Brandon K Wilder
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR, 97006, USA
| | - Vladimir Vigdorovich
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Sara Carbonetti
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Nana Minkah
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Nina Hertoghs
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Andrew Raappana
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Hayley Cardamone
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Brian G Oliver
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Olesya Trakhimets
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Sudhir Kumar
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Nicholas Dambrauskas
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Silvia A Arredondo
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Nelly Camargo
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Annette M Seilie
- Department of Laboratory Medicine and Pathology and Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Sean C Murphy
- Department of Laboratory Medicine and Pathology and Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Stefan H I Kappe
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA.
- Department of Pediatrics, University of Washington, Seattle, WA, USA.
- Department of Global Health, University of Washington, Seattle, WA, USA.
| | - D Noah Sather
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA.
- Department of Pediatrics, University of Washington, Seattle, WA, USA.
- Department of Global Health, University of Washington, Seattle, WA, USA.
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16
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Matsubara J, Chang M, Seilie AM, Murphy SC. Flow Cytometric Sorting of Infected Erythrocytes Demonstrates Reliable Detection of Individual Ring-Stage Plasmodium falciparum Parasites by Plasmodium 18S rRNA Reverse Transcription Polymerase Chain Reaction. Am J Trop Med Hyg 2022; 106:tpmd211226. [PMID: 35405648 PMCID: PMC9209910 DOI: 10.4269/ajtmh.21-1226] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 01/17/2022] [Indexed: 11/12/2022] Open
Abstract
Molecular diagnostic tests for Plasmodium falciparum parasites are increasingly used to enable ultrasensitive detection of infection in clinical trials and field surveillance studies. Ribonucleic acid (RNA)-based assays targeting 18S rRNA are particularly sensitive with limits of detection reported to comprise a single infected red blood cell (RBC) in a relatively large volume of blood. However, the validation testing at such limiting concentrations is hampered by the so-called Poisson distribution of such rare events, which can lead laboratorians to inaccurately set the limit of detection higher (i.e., less sensitive) than the assay can actually detect. Here we set out to formally demonstrate the analytical sensitivity of the Plasmodium 18S rRNA quantitative reverse transcription PCR (qRT-PCR). Fluorescence-activated cell sorting (FACS) was used on synchronous P. falciparum cultures doubly stained for DNA and RNA and was followed by qRT-PCR on the individual sorted cells spiked with negative whole blood. Over 95% of individual single-ring infected RBCs were detected by qRT-PCR. The formally measured median 18S rRNA content per individual ring-stage P. falciparum parasite was 9,550 copies (interquartile range 8,130-12,300). Thus, one can confidently rely on Plasmodium 18S rRNA qRT-PCR to detect one parasite per 50-µL blood sample.
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Affiliation(s)
- Jokichi Matsubara
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington
| | - Ming Chang
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington
| | - Annette M Seilie
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington
| | - Sean C Murphy
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington
- Department of Microbiology, University of Washington, Seattle, Washington
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17
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Goswami D, Kumar S, Betz W, Armstrong JM, Haile MT, Camargo N, Parthiban C, Seilie AM, Murphy SC, Vaughan AM, Kappe SH. A Plasmodium falciparum ATP binding cassette transporter is essential for liver stage entry into schizogony. iScience 2022; 25:104224. [PMID: 35521513 PMCID: PMC9061783 DOI: 10.1016/j.isci.2022.104224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 03/01/2022] [Accepted: 04/06/2022] [Indexed: 11/27/2022] Open
Abstract
Plasmodium sporozoites invade hepatocytes and transform into liver stages within a parasitophorous vacuole (PV). The parasites then grow and replicate their genome to form exoerythrocytic merozoites that infect red blood cells. We report that the human malaria parasite Plasmodium falciparum (Pf) expresses a C-type ATP-binding cassette transporter, Pf ABCC2, which marks the transition from invasive sporozoite to intrahepatocytic early liver stage. Using a humanized mouse infection model, we show that Pf ABCC2 localizes to the parasite plasma membrane in early and mid-liver stage parasites but is not detectable in late liver stages. Pf abcc2— sporozoites invade hepatocytes, form a PV, and transform into liver stage trophozoites but cannot transition to exoerythrocytic schizogony and fail to transition to blood stage infection. Thus, Pf ABCC2 is an expression marker for early phases of parasite liver infection and plays an essential role in the successful initiation of liver stage replication. Pf ABCC2 expression marks the transition from sporozoite to early liver stage Pf ABCC2 localizes to the early and mid-liver stage plasma membrane Pf ABCC2 is critical for initiation of exoerythrocytic schizogony Pf abcc2– liver stages fail to transition to blood stage infection
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18
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Shaffer D, Kumwenda J, Chen H, Akelo V, Angira F, Kosgei J, Tonui R, Ssali F, McKhann A, Hogg E, Stewart VA, Murphy SC, Coombs R, Schooley R. Brief Report: No Differences Between Lopinavir/Ritonavir and Nonnucleoside Reverse Transcriptase Inhibitor-Based Antiretroviral Therapy on Clearance of Plasmodium falciparum Subclinical Parasitemia in Adults Living With HIV Starting Treatment (A5297). J Acquir Immune Defic Syndr 2022; 89:178-182. [PMID: 34693933 PMCID: PMC9425486 DOI: 10.1097/qai.0000000000002839] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 09/20/2021] [Indexed: 02/03/2023]
Abstract
BACKGROUND HIV protease inhibitors anti-Plasmodium falciparum activity in adults remains uncertain. METHODS Adults with HIV CD4+ counts >200 cells/mm3 starting antiretroviral therapy (ART) with P. falciparum subclinical parasitemia (Pf SCP) were randomized 1:1 to (step 1) protease inhibitor lopinavir/ritonavir (LPV/r)-based (arm A) or nonnucleoside reverse transcriptase inhibitor (nNRTI)-based ART (arm B) for 15 days. In step 2, participants received nNRTI-based ART and trimethoprim/sulfamethoxazole prophylaxis for 15 days. P. falciparum SCP clearance was measured by polymerase chain reaction. The Fisher exact test [95% exact confidence interval (CI)] was used to compare proportions of P. falciparum SCP clearance (<10 parasites/μL on 3 occasions within 24 hours) between LPV/r and nNRTI arms at day 15. The Kaplan-Meier method and log-rank test were used to compare time-to-clearance. RESULTS Fifty-two adults from Kenya, Malawi, and Uganda with a median age = 31 (Q1, Q3: 24-39) years, 33% women, with baseline median CD4+ counts of 324 (259-404) cells/mm3, median HIV-1 RNA viremia of 5.18 log10 copies/mL (4.60-5.71), and median estimated P. falciparum density of 454 parasites/μL (83-2219) enrolled in the study. Forty-nine (94%) participants completed the study. At day 15, there was no statistically significant difference in the proportions of P. falciparum SCP clearance between the LPV/r (23.1% clearance; 6 of the 26) and nNRTI (26.9% clearance; 7 of the 26) arms [between-arm difference 3.9% (95% CI, -21.1% to 28.4%; P = 1.00)]. No significant difference in time-to-clearance was observed between the arms (P = 0.80). CONCLUSIONS In a small randomized study of adults starting ART with P. falciparum SCP, no statistically significant differences were seen between LPV/r- and nNRTI-based ART in P. falciparum SCP clearance after 15 days of treatment.
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Affiliation(s)
- Douglas Shaffer
- U.S. Centers for Disease Control and Prevention, Kigali, Rwanda (at time of research)
| | | | - Huichao Chen
- Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Victor Akelo
- Kenya Medical Research Institute, Center for Global Health (KEMRI/CGHR)/Emory-CDC CTU, Kisumu, Kenya
| | - Francis Angira
- Kenya Medical Research Institute, Center for Global Health (KEMRI/CGHR)/Emory-CDC CTU, Kisumu, Kenya
| | - Josphat Kosgei
- Kenya Medical Research Institute/United States Army Medical Research Directorate-Africa/Kenya, Kericho, Kenya
| | - Ronald Tonui
- Moi University School of Medicine, Eldoret, Kenya
| | | | - Ashley McKhann
- Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Evelyn Hogg
- Social & Scientific Systems, Inc., A DLH Holdings Company, Silver Spring, MD, USA
| | - V. Ann Stewart
- Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Sean C. Murphy
- Department of Laboratory Medicine and Pathology, University of Washington; Department of Microbiology, University of Washington; Center for Emerging and Re-emerging Infectious Diseases, University of Washington; Seattle, WA, USA
| | - Robert Coombs
- Department of Laboratory Medicine and Pathology; Department of Medicine, University of Washington, Seattle, WA, USA
| | - Robert Schooley
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
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19
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Glasgow HL, Cruz K, Murphy SC. Reverse-transcription PCR increases sensitivity of broad-range fungal detection in bronchoalveolar lavage fluid. Med Mycol 2021; 60:6433194. [PMID: 34878120 DOI: 10.1093/mmy/myab061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 09/24/2021] [Indexed: 11/13/2022] Open
Abstract
Broad-range PCR targeting 28S D1-D2 ribosomal DNA (rDNA) identifies numerous fungi but has limited sensitivity in clinical specimens. Ribosomal RNA (rRNA) vastly outnumbers rDNA, suggesting reverse transcription (RT)-PCR could improve detection. Among contrived samples, RT-PCR decreased 28S PCR cycle threshold values by 10--12 cycles and lowered the limit of detection > 2000-fold. Among 32 bronchoalveolar lavage specimens, RT-PCR detected 12/15 (80%) fungal PCR- or culture-positive specimens, versus 6/12 (50%) by 28S PCR, 9/12 (75%) by any fungal PCR, and 13/15 (87%) by culture. RT-PCR newly identified fungi in 4/17 (24%) PCR- and culture-negative specimens. RT substantially increased 28S PCR sensitivity overall. LAY SUMMARY Fungal infection remains difficult to diagnose in the laboratory. Here, we have shown that detecting ribosomal RNA and DNA, rather than only ribosomal DNA, in a broad range fungal assay results in a significant enhancement in the ability to detect and identify fungal pathogens in clinical samples.
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Affiliation(s)
- Heather L Glasgow
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, 98195, USA
| | - Kurtis Cruz
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, 98195, USA
| | - Sean C Murphy
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, 98195, USA.,Department of Microbiology, University of Washington, Seattle, Washington, 98195, USA
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20
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Application of dried blood spot sample pooling strategies for Plasmodium 18S rRNA biomarker testing to facilitate identification of infected persons in large-scale epidemiological studies. Malar J 2021; 20:391. [PMID: 34620192 PMCID: PMC8499573 DOI: 10.1186/s12936-021-03907-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 09/06/2021] [Indexed: 11/10/2022] Open
Abstract
Background Plasmodium 18S rRNA is a sensitive biomarker for detecting Plasmodium infection in human blood. Dried blood spots (DBS) are a practical sample type for malaria field studies to collect, store, and transport large quantities of blood samples for diagnostic testing. Pooled testing is a common way to reduce reagent costs and labour. This study examined performance of the Plasmodium 18S rRNA biomarker assay for DBS, improved assay sensitivity for pooled samples, and created graphical user interface (GUI) programmes for facilitating optimal pooling. Methods DBS samples of varied parasite densities from clinical specimens, Plasmodium falciparum in vitro culture, and P. falciparum Armored RNA® were tested using the Plasmodium 18S rRNA quantitative triplex reverse transcription polymerase chain reaction (qRT-PCR) assay and a simplified duplex assay. DBS sample precision, linearity, limit of detection (LoD) and stability at varied storage temperatures were evaluated. Novel GUIs were created to model two-stage hierarchy, square matrix, and three-stage hierarchy pooling strategies with samples of varying positivity rates and estimated test counts. Seventy-eight DBS samples from persons residing in endemic regions with sub-patent infections were tested in pools and deconvoluted to identify positive cases. Results Assay performance showed linearity for DBS from 4 × 107 to 5 × 102 parasites/mL with strong correlation to liquid blood samples (r2 > 0.96). There was a minor quantitative reduction in DBS rRNA copies/mL compared to liquid blood samples. Analytical sensitivity for DBS was estimated 5.3 log copies 18S rRNA/mL blood (28 estimated parasites/mL). Properly preserved DBS demonstrated minimal degradation of 18S rRNA when stored at ambient temperatures for one month. A simplified duplex qRT-PCR assay omitting the human mRNA target showed improved analytical sensitivity, 1 parasite/mL blood, and was optimized for pooling. Optimal pooling sizes varied depending on prevalence. A pilot DBS study of the two-stage hierarchy pooling scheme corroborated results previously determined by testing individual DBS. Conclusions The Plasmodium 18S rRNA biomarker assay can be applied to DBS collected in field studies. The simplified Plasmodium qRT-PCR assay and GUIs have been established to provide efficient means to test large quantities of DBS samples. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03907-8.
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Kapulu MC, Njuguna P, Hamaluba M, Kimani D, Ngoi JM, Musembi J, Ngoto O, Otieno E, Billingsley PF. Safety and PCR monitoring in 161 semi-immune Kenyan adults following controlled human malaria infection. JCI Insight 2021; 6:e146443. [PMID: 34264864 PMCID: PMC8492329 DOI: 10.1172/jci.insight.146443] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 07/14/2021] [Indexed: 11/26/2022] Open
Abstract
BACKGROUNDNaturally acquired immunity to malaria is incompletely understood. We used controlled human malaria infection (CHMI) to study the impact of past exposure on malaria in Kenyan adults in relation to infection with a non-Kenyan parasite strain.METHODSWe administered 3.2 × 103 aseptic, purified, cryopreserved Plasmodium falciparum sporozoites (Sanaria PfSPZ Challenge, NF54 West African strain) by direct venous inoculation and undertook clinical monitoring and serial quantitative PCR (qPCR) of the 18S ribosomal RNA gene. The study endpoint was met when parasitemia reached 500 or more parasites per μL blood, clinically important symptoms were seen, or at 21 days after inoculation. All volunteers received antimalarial drug treatment upon meeting the endpoint.RESULTSOne hundred and sixty-one volunteers underwent CHMI between August 4, 2016, and February 14, 2018. CHMI was well tolerated, with no severe or serious adverse events. Nineteen volunteers (11.8%) were excluded from the analysis based on detection of antimalarial drugs above the minimal inhibitory concentration or parasites genotyped as non-NF54. Of the 142 volunteers who were eligible for analysis, 26 (18.3%) had febrile symptoms and were treated; 30 (21.1%) reached 500 or more parasites per μL and were treated; 53 (37.3%) had parasitemia without meeting thresholds for treatment; and 33 (23.2%) remained qPCR negative.CONCLUSIONWe found that past exposure to malaria, as evidenced by location of residence, in some Kenyan adults can completely suppress in vivo growth of a parasite strain originating from outside Kenya.TRIAL REGISTRATIONClinicalTrials.gov NCT02739763.FUNDINGWellcome Trust.
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Affiliation(s)
- Melissa C. Kapulu
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Patricia Njuguna
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mainga Hamaluba
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Domtila Kimani
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Joyce M. Ngoi
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Janet Musembi
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Omar Ngoto
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Edward Otieno
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
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22
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Clustering of subpatent infections in households with asymptomatic rapid diagnostic test-positive cases in Bioko Island, Equatorial Guinea independent of travel to regions of higher malaria endemicity: a cross-sectional study. Malar J 2021; 20:313. [PMID: 34247643 PMCID: PMC8274032 DOI: 10.1186/s12936-021-03844-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 07/03/2021] [Indexed: 11/27/2022] Open
Abstract
Background Prevalence of falciparum malaria on Bioko Island remains high despite sustained, intensive control. Progress may be hindered by high proportions of subpatent infections that are not detected by rapid diagnostic tests (RDT) but contribute to onward transmission, and by imported infections. Better understanding of the relationship between subpatent infections and RDT-detected infections, and whether this relationship is different from imported versus locally acquired infections, is imperative to better understand the sources of infection and mechanisms of transmission to tailor more effective interventions. Methods Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was performed on a sub-set of samples from the 2015 Malaria Indicator Survey to identify subpatent infections. Households with RDT(+) individuals were matched 1:4 with households with no RDT(+) individuals. The association between living in a household with an RDT(+) individual and having a subpatent infection was evaluated using multivariate hierarchical logistic regression models with inverse probability weights for selection. To evaluate possible modification of the association by potential importation of the RDT(+) case, the analysis was repeated among strata of matched sets based on the reported eight-week travel history of the RDT(+) individual(s). Results There were 142 subpatent infections detected in 1,400 individuals (10.0%). The prevalence of subpatent infections was higher in households with versus without an RDT(+) individual (15.0 vs 9.1%). The adjusted prevalence odds of subpatent infection were 2.59-fold greater (95% CI: 1.31, 5.09) for those in a household with an RDT(+) individual compared to individuals in a household without RDT(+) individuals. When stratifying by travel history of the RDT(+) individual, the association between subpatent infections and RDT(+) infections was stronger in the strata in which the RDT(+) individual(s) had not recently travelled (adjusted prevalence odds ratio (aPOR) 2.95; 95% CI:1.17, 7.41), and attenuated in the strata in which recent travel was reported (aPOR 1.76; 95% CI: 0.54, 5.67). Conclusions There is clustering of subpatent infections around RDT(+) individual(s) when both imported and local infection are suspected. Future control strategies that aim to treat whole households in which an RDT(+) individual is found may target a substantial portion of infections that would otherwise not be detected. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03844-6.
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23
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Mwakingwe-Omari A, Healy SA, Lane J, Cook DM, Kalhori S, Wyatt C, Kolluri A, Marte-Salcedo O, Imeru A, Nason M, Ding LK, Decederfelt H, Duan J, Neal J, Raiten J, Lee G, Hume JCC, Jeon JE, Ikpeama I, Kc N, Chakravarty S, Murshedkar T, Church LWP, Manoj A, Gunasekera A, Anderson C, Murphy SC, March S, Bhatia SN, James ER, Billingsley PF, Sim BKL, Richie TL, Zaidi I, Hoffman SL, Duffy PE. Two chemoattenuated PfSPZ malaria vaccines induce sterile hepatic immunity. Nature 2021; 595:289-294. [PMID: 34194041 PMCID: PMC11127244 DOI: 10.1038/s41586-021-03684-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 06/01/2021] [Indexed: 02/06/2023]
Abstract
The global decline in malaria has stalled1, emphasizing the need for vaccines that induce durable sterilizing immunity. Here we optimized regimens for chemoprophylaxis vaccination (CVac), for which aseptic, purified, cryopreserved, infectious Plasmodium falciparum sporozoites (PfSPZ) were inoculated under prophylactic cover with pyrimethamine (PYR) (Sanaria PfSPZ-CVac(PYR)) or chloroquine (CQ) (PfSPZ-CVac(CQ))-which kill liver-stage and blood-stage parasites, respectively-and we assessed vaccine efficacy against homologous (that is, the same strain as the vaccine) and heterologous (a different strain) controlled human malaria infection (CHMI) three months after immunization ( https://clinicaltrials.gov/ , NCT02511054 and NCT03083847). We report that a fourfold increase in the dose of PfSPZ-CVac(PYR) from 5.12 × 104 to 2 × 105 PfSPZs transformed a minimal vaccine efficacy (low dose, two out of nine (22.2%) participants protected against homologous CHMI), to a high-level vaccine efficacy with seven out of eight (87.5%) individuals protected against homologous and seven out of nine (77.8%) protected against heterologous CHMI. Increased protection was associated with Vδ2 γδ T cell and antibody responses. At the higher dose, PfSPZ-CVac(CQ) protected six out of six (100%) participants against heterologous CHMI three months after immunization. All homologous (four out of four) and heterologous (eight out of eight) infectivity control participants showed parasitaemia. PfSPZ-CVac(CQ) and PfSPZ-CVac(PYR) induced a durable, sterile vaccine efficacy against a heterologous South American strain of P. falciparum, which has a genome and predicted CD8 T cell immunome that differs more strongly from the African vaccine strain than other analysed African P. falciparum strains.
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Affiliation(s)
- Agnes Mwakingwe-Omari
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
- Center for Vaccine Research, GlaxoSmithKline, Rockville, MD, USA
| | - Sara A Healy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jacquelyn Lane
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - David M Cook
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Sahand Kalhori
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Charles Wyatt
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Aarti Kolluri
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Omely Marte-Salcedo
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Alemush Imeru
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Martha Nason
- Biostatistical Research Branch, National Institute of Allergy and Infectious Diseases, Rockville, MD, USA
| | - Lei K Ding
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Hope Decederfelt
- Clinical Center Pharmacy Department, National Institutes of Health, Bethesda, MD, USA
| | - Junhui Duan
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jillian Neal
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jacob Raiten
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Grace Lee
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jen C C Hume
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jihyun E Jeon
- Clinical Center Pharmacy Department, National Institutes of Health, Bethesda, MD, USA
| | - Ijeoma Ikpeama
- Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - Natasha Kc
- Sanaria, Rockville, MD, USA
- Protein Potential, Rockville, MD, USA
| | | | | | | | | | | | - Charles Anderson
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Sean C Murphy
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
- Department of Microbiology, University of Washington, Seattle, WA, USA
- Seattle Malaria Clinical Trials Center, Fred Hutch Cancer Research Center, Seattle, WA, USA
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Sandra March
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sangeeta N Bhatia
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
- Koch Institute for Integrative Cancer Research, Cambridge, MA, USA
- Broad Institute, Cambridge, MA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
- Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | | | | | - B Kim Lee Sim
- Sanaria, Rockville, MD, USA
- Protein Potential, Rockville, MD, USA
| | | | - Irfan Zaidi
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | | | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
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24
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Kamau E, Bennett JW, Yadava A. Safety and Tolerability of Mosquito-Bite Induced Controlled Human Infection with P. vivax in Malaria-Naïve Study Participants - Clinical Profile and Utility of Molecular Diagnostic Methods. J Infect Dis 2021; 225:146-156. [PMID: 34161579 DOI: 10.1093/infdis/jiab332] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 06/22/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Plasmodium vivax controlled-human-malaria-infection (PvCHMI) is an important tool for the evaluation of drugs, vaccines and pathologies associated with this parasite. However, there is little data on its safety due to the limited number of PvCHMIs performed to-date. METHODS We report clinical and laboratory data collected, to include hematological and biochemical profiles and adverse-events, following mosquito-bite induced PvCHMI in malaria-naïve study-participants (ClinicalTrials.gov_NCT01157897). Malaria diagnosis and treatment initiation was based on microscopic analysis of Giemsa-stained slides. Exploratory molecular assays were used to detect parasites using real-time PCR. RESULTS Adverse-events (AEs) were mild to moderate and no study-related severe AEs were observed in any of the study participants. Majority of the symptoms were transient, resolving within 48hours. Molecular-diagnostic methods detected parasitemia in 100% of study-participants before malaria diagnosis using microscopy. Of the reported AEs, microscopy detected 67-100%, qPCR 79-100% and qRT-PCR detected 96-100% of the study-participants prior to appearance of symptoms. Almost all the symptoms appeared after the initiation of treatment, likely as a known consequence of drug treatment. CONCLUSIONS PvCHMI is safe with majority of the infections being detected prior to the appearance of clinical symptoms, which can be further alleviated by using sensitive molecular methods for clinical diagnosis.
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Affiliation(s)
- Edwin Kamau
- Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America.,Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Jason W Bennett
- Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America.,Multidrug-resistant organism Repository & Surveillance Network, Bacterial Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Anjali Yadava
- Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
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25
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Murphy SC, Deye GA, Sim BKL, Galbiati S, Kennedy JK, Cohen KW, Chakravarty S, KC N, Abebe Y, James ER, Kublin JG, Hoffman SL, Richie TL, Jackson LA. PfSPZ-CVac efficacy against malaria increases from 0% to 75% when administered in the absence of erythrocyte stage parasitemia: A randomized, placebo-controlled trial with controlled human malaria infection. PLoS Pathog 2021; 17:e1009594. [PMID: 34048504 PMCID: PMC8191919 DOI: 10.1371/journal.ppat.1009594] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 06/10/2021] [Accepted: 04/29/2021] [Indexed: 11/18/2022] Open
Abstract
PfSPZ-CVac combines 'PfSPZ Challenge', which consists of infectious Plasmodium falciparum sporozoites (PfSPZ), with concurrent antimalarial chemoprophylaxis. In a previously-published PfSPZ-CVac study, three doses of 5.12x104 PfSPZ-CVac given 28 days apart had 100% vaccine efficacy (VE) against controlled human malaria infection (CHMI) 10 weeks after the last immunization, while the same dose given as three injections five days apart had 63% VE. Here, we conducted a dose escalation trial of similarly condensed schedules. Of the groups proceeding to CHMI, the first study group received three direct venous inoculations (DVIs) of a dose of 5.12x104 PfSPZ-CVac seven days apart and the next full dose group received three DVIs of a higher dose of 1.024x105 PfSPZ-CVac five days apart. CHMI (3.2x103 PfSPZ Challenge) was performed by DVI 10 weeks after the last vaccination. In both CHMI groups, transient parasitemia occurred starting seven days after each vaccination. For the seven-day interval group, the second and third vaccinations were therefore administered coincident with parasitemia from the prior vaccination. Parasitemia was associated with systemic symptoms which were severe in 25% of subjects. VE in the seven-day group was 0% (7/7 infected) and in the higher-dose, five-day group was 75% (2/8 infected). Thus, the same dose of PfSPZ-CVac previously associated with 63% VE when given on a five-day schedule in the prior study had zero VE here when given on a seven-day schedule, while a double dose given on a five-day schedule here achieved 75% VE. The relative contributions of the five-day schedule and/or the higher dose to improved VE warrant further investigation. It is notable that administration of PfSPZ-CVac on a schedule where vaccine administration coincided with blood-stage parasitemia was associated with an absence of sterile protective immunity. Clinical trials registration: NCT02773979.
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Affiliation(s)
- Sean C. Murphy
- Seattle Malaria Clinical Trials Center, Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
- Center for Emerging and Re-emerging Infectious Diseases, Seattle, Washington, United States of America
| | - Gregory A. Deye
- Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - B. Kim Lee Sim
- Sanaria Inc., Rockville, Maryland, United States of America
| | - Shirley Galbiati
- The Emmes Company, Rockville, Maryland, United States of America
| | | | - Kristen W. Cohen
- Seattle Malaria Clinical Trials Center, Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | | | - Natasha KC
- Sanaria Inc., Rockville, Maryland, United States of America
| | - Yonas Abebe
- Sanaria Inc., Rockville, Maryland, United States of America
| | - Eric R. James
- Sanaria Inc., Rockville, Maryland, United States of America
| | - James G. Kublin
- Seattle Malaria Clinical Trials Center, Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
| | | | | | - Lisa A. Jackson
- Kaiser Permanente Washington Health Research Institute, Seattle, Washington, United States of America
- * E-mail:
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26
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Schäfer C, Dambrauskas N, Reynolds LM, Trakhimets O, Raappana A, Flannery EL, Roobsoong W, Sattabongkot J, Mikolajczak SA, Kappe SHI, Sather DN. Partial protection against P. vivax infection diminishes hypnozoite burden and blood-stage relapses. Cell Host Microbe 2021; 29:752-756.e4. [PMID: 33857426 DOI: 10.1016/j.chom.2021.03.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/16/2021] [Accepted: 03/18/2021] [Indexed: 01/23/2023]
Abstract
Latent forms of Plasmodium vivax, called hypnozoites, cause malaria relapses from the liver into the bloodstream and are a major obstacle to malaria eradication. To experimentally assess the impact of a partially protective pre-erythrocytic vaccine on reducing Plasmodium vivax relapses, we developed a liver-humanized mouse model that allows monitoring of relapses directly in the blood. We passively infused these mice with a suboptimal dose of an antibody that targets the circumsporozoite protein prior to challenge with P. vivax sporozoites. Although this regimen did not completely prevent primary infection, antibody-treated mice experienced 62% fewer relapses. The data constitute unprecedented direct experimental evidence that suboptimal efficacy of infection-blocking antibodies, while not completely preventing primary infection, has a pronounced benefit in reducing the number of relapses. These findings suggest that a partially efficacious pre-erythrocytic Plasmodium vivax vaccine can have a disproportionately high impact in positive public health outcomes.
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Affiliation(s)
- Carola Schäfer
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Nicholas Dambrauskas
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Laura M Reynolds
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Olesya Trakhimets
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Andrew Raappana
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Erika L Flannery
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Wanlapa Roobsoong
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Sebastian A Mikolajczak
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Stefan H I Kappe
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA; Department of Pediatrics, University of Washington, Seattle, WA 98105, USA; Department of Global Health, University of Washington, Seattle, WA 98105, USA.
| | - D Noah Sather
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA; Department of Pediatrics, University of Washington, Seattle, WA 98105, USA; Department of Global Health, University of Washington, Seattle, WA 98105, USA.
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27
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Wang CYT, Ballard EL, Pava Z, Marquart L, Gaydon J, Murphy SC, Whiley D, O'Rourke P, McCarthy JS. Analytical validation of a real-time hydrolysis probe PCR assay for quantifying Plasmodium falciparum parasites in experimentally infected human adults. Malar J 2021; 20:181. [PMID: 33838672 PMCID: PMC8035755 DOI: 10.1186/s12936-021-03717-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 03/29/2021] [Indexed: 11/10/2022] Open
Abstract
Background Volunteer infection studies have become a standard model for evaluating drug efficacy against Plasmodium infections. Molecular techniques such as qPCR are used in these studies due to their ability to provide robust and accurate estimates of parasitaemia at increased sensitivity compared to microscopy. The validity and reliability of assays need to be ensured when used to evaluate the efficacy of candidate drugs in clinical trials. Methods A previously described 18S rRNA gene qPCR assay for quantifying Plasmodium falciparum in blood samples was evaluated. Assay performance characteristics including analytical sensitivity, reportable range, precision, accuracy and specificity were assessed using experimental data and data compiled from phase 1 volunteer infection studies conducted between 2013 and 2019. Guidelines for validation of laboratory-developed molecular assays were followed. Results The reportable range was 1.50 to 6.50 log10 parasites/mL with a limit of detection of 2.045 log10 parasites/mL of whole blood based on a parasite diluted standard series over this range. The assay was highly reproducible with minimal intra-assay (SD = 0.456 quantification cycle (Cq) units [0.137 log10 parasites/mL] over 21 replicates) and inter-assay (SD = 0.604 Cq units [0.182 log10 parasites/mL] over 786 qPCR runs) variability. Through an external quality assurance program, the QIMR assay was shown to generate accurate results (quantitative bias + 0.019 log10 parasites/mL against nominal values). Specificity was 100% after assessing 164 parasite-free human blood samples. Conclusions The 18S rRNA gene qPCR assay is specific and highly reproducible and can provide reliable and accurate parasite quantification. The assay is considered fit for use in evaluating drug efficacy in malaria clinical trials. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03717-y.
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Affiliation(s)
- Claire Y T Wang
- Centre for Children's Health Research, Children's Health Queensland, Brisbane, Australia. .,Child Health Research Centre, The University of Queensland, Brisbane, Australia.
| | - Emma L Ballard
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Zuleima Pava
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Louise Marquart
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Jane Gaydon
- Centre for Children's Health Research, Children's Health Queensland, Brisbane, Australia.,Child Health Research Centre, The University of Queensland, Brisbane, Australia
| | - Sean C Murphy
- Departments of Laboratory Medicine and Microbiology, University of Washington, Seattle, WA, USA.,Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - David Whiley
- Centre for Children's Health Research, Children's Health Queensland, Brisbane, Australia.,UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Brisbane, Australia
| | - Peter O'Rourke
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Australia.,School of Medicine, The University of Queensland, Brisbane, Australia
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Ultrasensitive Diagnostics for Low-Density Asymptomatic Plasmodium falciparum Infections in Low-Transmission Settings. J Clin Microbiol 2021; 59:JCM.01508-20. [PMID: 33148707 DOI: 10.1128/jcm.01508-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The emergence of multidrug-resistant Plasmodium falciparum malaria in Southeast Asia (SEA) has accelerated regional malaria elimination efforts. Most malaria in this and other low-transmission settings exists in asymptomatic individuals, which conventional diagnostic tests lack the sensitivity to detect. This has led to the development of new ultrasensitive diagnostics that are capable of detecting these low-parasitemia infections. This review summarizes the current status of ultrasensitive technologies, including PCR and loop-mediated isothermal amplification (LAMP)-based methods, as well as a newly developed ultrasensitive rapid diagnostic test (uRDT). The sensitivity, specificity, and field performance of these platforms will be examined, as well as their suitability for use in resource-limited settings to aid in malaria elimination efforts. uRDTs, with their improved sensitivity, are now able to detect approximately half of asymptomatic infections, providing a useful point-of-contact tool for malaria surveillance. The increased sensitivity and high-throughput nature of PCR-based tests make them ideal for screening large populations in places where laboratory capacity exists, and the recent commercialization of malaria LAMP kits should facilitate their adoption as a public health tool in places where such infrastructure is lacking. Finally, recent advances with dried blood spots may enable utilization of the extensive laboratory infrastructure of higher-income countries to assist with molecular surveillance in support of malaria elimination. If malaria is to be eliminated in SEA and other low-endemicity regions, then ultrasensitive diagnostics will likely play a key role in identifying and clearing the vast asymptomatic pool of infections that are common to these regions.
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Abstract
Introduction: An effective vaccine against malaria forms a global health priority. Both naturally acquired immunity and sterile protection induced by irradiated sporozoite immunization were described decades ago. Still no vaccine exists that sufficiently protects children in endemic areas. Identifying immunological correlates of vaccine efficacy can inform rational vaccine design and potentially accelerate clinical development.Areas covered: We discuss recent research on immunological correlates of malaria vaccine efficacy, including: insights from state-of-the-art omics platforms and systems vaccinology analyses; functional anti-parasitic assays; pre-immunization predictors of vaccine efficacy; and comparison of correlates of vaccine efficacy against controlled human malaria infections (CHMI) and against naturally acquired infections.Expert Opinion: Effective vaccination may be achievable without necessarily understanding immunological correlates, but the relatively disappointing efficacy of malaria vaccine candidates in target populations is concerning. Hypothesis-generating omics and systems vaccinology analyses, alongside assessment of pre-immunization correlates, have the potential to bring about paradigm-shifts in malaria vaccinology. Functional assays may represent in vivo effector mechanisms, but have scarcely been formally assessed as correlates. Crucially, evidence is still meager that correlates of vaccine efficacy against CHMI correspond with those against naturally acquired infections in target populations. Finally, the diversity of immunological assays and efficacy endpoints across malaria vaccine trials remains a major confounder.
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Affiliation(s)
| | - Matthew B B McCall
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands.,Institut für Tropenmedizin, Universitätsklinikum Tübingen, Tübingen, Germany.,Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
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30
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Smith TAD, AbdelKarem OA, Irlam-Jones JJ, Lane B, Valentine H, Bibby BAS, Denley H, Choudhury A, West CML. Selection of endogenous control genes for normalising gene expression data derived from formalin-fixed paraffin-embedded tumour tissue. Sci Rep 2020; 10:17258. [PMID: 33057113 PMCID: PMC7560892 DOI: 10.1038/s41598-020-74380-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 09/28/2020] [Indexed: 12/19/2022] Open
Abstract
Quantitative real time polymerase chain reaction (qPCR) data are normalised using endogenous control genes. We aimed to: (1) demonstrate a pathway to identify endogenous control genes for qPCR analysis of formalin-fixed paraffin-embedded (FFPE) tissue using bladder cancer as an exemplar; and (2) examine the influence of probe length and sample age on PCR amplification and co-expression of candidate genes on apparent expression stability. RNA was extracted from prospective and retrospective samples and subject to qPCR using TaqMan human endogenous control arrays or single tube assays. Gene stability ranking was assessed using coefficient of variation (CoV), GeNorm and NormFinder. Co-expressed genes were identified from The Cancer Genome Atlas (TCGA) using the on-line gene regression analysis tool GRACE. Cycle threshold (Ct) values were lower for prospective (19.49 ± 2.53) vs retrospective (23.8 ± 3.32) tissues (p < 0.001) and shorter vs longer probes. Co-expressed genes ranked as the most stable genes in the TCGA cohort by GeNorm when analysed together but ranked lower when analysed individually omitting co-expressed genes indicating bias. Stability values were < 1.5 for the 20 candidate genes in the prospective cohort. As they consistently ranked in the top ten by CoV, GeNorm and Normfinder, UBC, RPLP0, HMBS, GUSB, and TBP are the most suitable endogenous control genes for bladder cancer qPCR.
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Affiliation(s)
- Tim A D Smith
- Translational Radiobiology Group, Division of Cancer Sciences, University of Manchester, Manchester Academic Health Centre, Christie Hospital NHS Found Trust, Manchester, M20 4BX, UK.
| | - Omneya A AbdelKarem
- Translational Radiobiology Group, Division of Cancer Sciences, University of Manchester, Manchester Academic Health Centre, Christie Hospital NHS Found Trust, Manchester, M20 4BX, UK
- Medical Research Institute, Alexandria University, 165 El-Horreya Avenue, El-Hadra, Alexandria, Egypt
| | - Joely J Irlam-Jones
- Translational Radiobiology Group, Division of Cancer Sciences, University of Manchester, Manchester Academic Health Centre, Christie Hospital NHS Found Trust, Manchester, M20 4BX, UK
| | - Brian Lane
- Translational Radiobiology Group, Division of Cancer Sciences, University of Manchester, Manchester Academic Health Centre, Christie Hospital NHS Found Trust, Manchester, M20 4BX, UK
| | - Helen Valentine
- Translational Radiobiology Group, Division of Cancer Sciences, University of Manchester, Manchester Academic Health Centre, Christie Hospital NHS Found Trust, Manchester, M20 4BX, UK
| | - Becky A S Bibby
- Translational Radiobiology Group, Division of Cancer Sciences, University of Manchester, Manchester Academic Health Centre, Christie Hospital NHS Found Trust, Manchester, M20 4BX, UK
| | - Helen Denley
- Pathology Centre, Shrewsbury and Telford NHS Trust, Royal Shrewsbury Hospital, Shrewsbury, SY3 8XQ, UK
| | - Ananya Choudhury
- Translational Radiobiology Group, Division of Cancer Sciences, University of Manchester, Manchester Academic Health Centre, Christie Hospital NHS Found Trust, Manchester, M20 4BX, UK
| | - Catharine M L West
- Translational Radiobiology Group, Division of Cancer Sciences, University of Manchester, Manchester Academic Health Centre, Christie Hospital NHS Found Trust, Manchester, M20 4BX, UK
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31
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Shears MJ, Seilie AM, Kim Lee Sim B, Hoffman SL, Murphy SC. Quantification of Plasmodium knowlesi versus Plasmodium falciparum in the rhesus liver: implications for malaria vaccine studies in rhesus models. Malar J 2020; 19:313. [PMID: 32867784 PMCID: PMC7457220 DOI: 10.1186/s12936-020-03385-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 07/13/2020] [Indexed: 02/07/2023] Open
Abstract
Background Rhesus macaques are valuable pre-clinical models for malaria vaccine development. The Plasmodium knowlesi/rhesus and Plasmodium falciparum/rhesus models are two established platforms for malaria vaccine testing, and both have previously been used to assess live-attenuated sporozoite vaccines. However, there is evidence that the susceptibility of the rhesus liver to P. knowlesi versus P. falciparum sporozoites likely differs, potentially complicating comparisons between these two platforms. Methods To quantify the differing susceptibility of rhesus to P. knowlesi and P. falciparum sporozoites, animals were infected by direct venous inoculation of purified, cryopreserved wild-type P. knowlesi sporozoites (PkSPZ) or P. falciparum sporozoites (PfSPZ). The entire liver was collected 5 days post-infection, and parasite burden in each liver lobe was quantified using an ultrasensitive Plasmodium 18S rRNA RT-PCR biomarker assay. The potential of using 18S rRNA copy number in the rhesus liver to directly measure the efficacy of vaccines targeting P. falciparum sporozoites and liver stages was also theoretically evaluated. Results Infection of rhesus with a high dose of PkSPZ led to consistently high burden liver stage infections (range 9.5–10.1 log10 copies 18S rRNA/g of liver), with similar amounts of parasite 18S rRNA detected in every liver lobe. Inoculation of rhesus with high doses of PfSPZ led to more variable, lower liver burdens (range 4.9–6.6 log10 copies 18S rRNA/g of liver in infected lobes), with parasite 18S rRNA below the limit of detection in some liver lobes. The low signal and heterogeneity of liver burden in the PfSPZ-infected animals indicates that even this extremely sensitive molecular assay cannot be used to assess reliably vaccine efficacy in the P. falciparum/rhesus platform. Conclusions Detection of 18S rRNA in the liver following high dose intravenous PfSPZ confirmed that rhesus are modestly susceptible to wild-type P. falciparum sporozoites. However, comparison of 18S rRNA RT-PCR biomarker signal indicates that the P. falciparum liver burden was 3–5 logs lower than in PkSPZ-infected animals. Quantification of this difference in liver stage burden will help guide and interpret data from pre-clinical studies of live-attenuated sporozoite vaccines in rhesus models.
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Affiliation(s)
- Melanie J Shears
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA.,Center for Emerging and Re-emerging Infectious Diseases, University of Washington, 750 Republican St., Seattle, WA, 98109, USA
| | - Annette M Seilie
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA.,Center for Emerging and Re-emerging Infectious Diseases, University of Washington, 750 Republican St., Seattle, WA, 98109, USA
| | - B Kim Lee Sim
- Sanaria, Inc., 9800 Medical Center Drive, Suite A209, Rockville, MD, 20850, USA
| | - Stephen L Hoffman
- Sanaria, Inc., 9800 Medical Center Drive, Suite A209, Rockville, MD, 20850, USA
| | - Sean C Murphy
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA. .,Center for Emerging and Re-emerging Infectious Diseases, University of Washington, 750 Republican St., Seattle, WA, 98109, USA. .,Washington National Primate Research Center, University of Washington, 1959 NE Pacific St., Seattle, WA, 98195, USA.
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32
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Vásquez AM, Vélez G, Medina A, Serra-Casas E, Campillo A, Gonzalez IJ, Murphy SC, Seilie AM, Ding XC, Tobón Castaño A. Evaluation of highly sensitive diagnostic tools for the detection of P. falciparum in pregnant women attending antenatal care visits in Colombia. BMC Pregnancy Childbirth 2020; 20:440. [PMID: 32736543 PMCID: PMC7393871 DOI: 10.1186/s12884-020-03114-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 07/16/2020] [Indexed: 12/20/2022] Open
Abstract
Background In low transmission settings early diagnosis is the main strategy to reduce adverse outcomes of malaria in pregnancy; however, microscopy and rapid diagnostic tests (RDTs) are inadequate for detecting low-density infections. We studied the performance of the highly sensitive-RDT (hsRDT) and the loop mediated isothermal DNA amplification (LAMP) for the detection of P. falciparum in pregnant women. Methods A cross-sectional study was conducted in two malaria-endemic municipalities in Colombia. We screened pregnant women in the context of an antenatal care program in health facilities and evaluated five tests (microscopy, conventional RDT, hsRDT, LAMP and nested polymerase chain reaction-PCR) for the detection of P. falciparum in peripheral blood, using a quantitative reverse transcription PCR (qRT-PCR) as the reference standard. Diagnostic performance of hsRDT and LAMP were compared with routine testing. Results The prevalence of P. falciparum was 4.5% by qRT-PCR, half of those infections were subpatent. The sensitivity of the hsRDT (64.1%) was slightly better compared to microscopy and cRDT (59 and 53.8% respectively). LAMP had the highest sensitivity (89.7%) for detecting P. falciparum and the ability to detect very low-density infections (minimum parasite density detected 0.08 p/μL). Conclusions There is an underestimation of Plasmodium spp. infections by tests routinely used in pregnant women attending antenatal care visits. LAMP methodology can be successfully implemented at local hospitals in malaria-endemic areas. The relevance of detecting and treating this sub-patent P. falciparum infections in pregnant women should be evaluated. Trial registration ClinicalTrials.gov, Identifier: NCT03172221, Date of registration: May 29, 2017.
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Affiliation(s)
- A M Vásquez
- Grupo Malaria, Facultad de Medicina, Universidad de Antioquia, Carrera 53 No. 61-30, Lab 610, Medellín, Colombia.
| | - G Vélez
- Grupo Malaria, Facultad de Medicina, Universidad de Antioquia, Carrera 53 No. 61-30, Lab 610, Medellín, Colombia
| | - A Medina
- Grupo Malaria, Facultad de Medicina, Universidad de Antioquia, Carrera 53 No. 61-30, Lab 610, Medellín, Colombia
| | | | | | | | - S C Murphy
- Malaria Molecular Diagnostic Laboratory, Departments of Laboratory Medicine and Microbiology and the Center for Emerging and Re-emerging Infectious Diseases, 750 Republican St, Seattle, WA, 98109, USA
| | - A M Seilie
- Malaria Molecular Diagnostic Laboratory, Departments of Laboratory Medicine and Microbiology and the Center for Emerging and Re-emerging Infectious Diseases, 750 Republican St, Seattle, WA, 98109, USA
| | | | - A Tobón Castaño
- Grupo Malaria, Facultad de Medicina, Universidad de Antioquia, Carrera 53 No. 61-30, Lab 610, Medellín, Colombia
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33
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Guirou EA, Schindler T, Hosch S, Donfack OT, Yoboue CA, Krähenbühl S, Deal A, Cosi G, Gondwe L, Mwangoka G, Masuki H, Salim N, Mpina M, Said J, Abdulla S, Hoffman SL, Nlavo BM, Maas C, Falla CC, Phiri WP, Garcia GA, Tanner M, Daubenberger C. Molecular malaria surveillance using a novel protocol for extraction and analysis of nucleic acids retained on used rapid diagnostic tests. Sci Rep 2020; 10:12305. [PMID: 32703999 PMCID: PMC7378824 DOI: 10.1038/s41598-020-69268-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 07/10/2020] [Indexed: 11/09/2022] Open
Abstract
The use of malaria rapid diagnostic tests (RDTs) as a source for nucleic acids that can be analyzed via nucleic acid amplification techniques has several advantages, including minimal amounts of blood, sample collection, simplified storage and shipping conditions at room temperature. We have systematically developed and extensively evaluated a procedure to extract total nucleic acids from used malaria RDTs. The co-extraction of DNA and RNA molecules from small volumes of dried blood retained on the RDTs allows detection and quantification of P. falciparum parasites from asymptomatic patients with parasite densities as low as 1 Pf/µL blood using reverse transcription quantitative PCR. Based on the extraction protocol we have developed the ENAR (Extraction of Nucleic Acids from RDTs) approach; a complete workflow for large-scale molecular malaria surveillance. Using RDTs collected during a malaria indicator survey we demonstrated that ENAR provides a powerful tool to analyze nucleic acids from thousands of RDTs in a standardized and high-throughput manner. We found several, known and new, non-synonymous single nucleotide polymorphisms in the propeller region of the kelch 13 gene among isolates circulating on Bioko Island, Equatorial Guinea.
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Affiliation(s)
- Etienne A Guirou
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Tobias Schindler
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
| | - Salome Hosch
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | | | - Charlene Aya Yoboue
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Silvan Krähenbühl
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Anna Deal
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Glenda Cosi
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Linda Gondwe
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland.,Ifakara Health Institute, Bagamoyo Branch, United Republic of Tanzania
| | - Grace Mwangoka
- Ifakara Health Institute, Bagamoyo Branch, United Republic of Tanzania
| | - Heavenlight Masuki
- Department of Paediatrics and Child Health, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania
| | - Nahya Salim
- Department of Paediatrics and Child Health, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania
| | - Maxmillian Mpina
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland.,Ifakara Health Institute, Bagamoyo Branch, United Republic of Tanzania
| | - Jongo Said
- Ifakara Health Institute, Bagamoyo Branch, United Republic of Tanzania
| | - Salim Abdulla
- Ifakara Health Institute, Bagamoyo Branch, United Republic of Tanzania
| | | | | | - Carl Maas
- Marathon EG Production Ltd, Malabo, Equatorial Guinea
| | | | - Wonder P Phiri
- Medical Care Development International, Malabo, Equatorial Guinea
| | | | - Marcel Tanner
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Claudia Daubenberger
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
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34
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Kublin JG, Murphy SC, Maenza J, Seilie AM, Jain JP, Berger D, Spera D, Zhao R, Soon RL, Czartoski JL, Potochnic MA, Duke E, Chang M, Vaughan A, Kappe SHI, Leong FJ, Pertel P, Prince WT. Safety, pharmacokinetics and causal prophylactic efficacy of KAF156 in a Plasmodium falciparum human infection study. Clin Infect Dis 2020; 73:e2407-e2414. [PMID: 32644127 DOI: 10.1093/cid/ciaa952] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 07/07/2020] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND KAF156 is a novel antimalarial drug that is active against both liver- and blood- stage Plasmodium parasites, including drug-resistant strains. Here, we investigated the causal prophylactic efficacy of KAF156 in a controlled human malaria infection (CHMI) model. METHODS In Part 1, healthy, malaria-naïve participants received 800 mg KAF156 or placebo three hr before CHMI with Pf-infected mosquitoes. In Part 2, KAF156 was administered as single doses of 800, 300, 100, 50, or 20 mg 21 hr post-CHMI. All participants received atovaquone/proguanil treatment if blood-stage infection was detected or on day 29. For each cohort, 7-14 subjects were enrolled to KAF156 treatment and up to four subjects to placebo. RESULTS KAF156 at all dose levels was safe and well tolerated. Two serious adverse events were reported - both resolved without sequelae and neither was considered related to KAF156. In Part 1, all participants treated with KAF156 and none of those randomized to placebo were protected against malaria infection. In Part 2, all participants treated with placebo or 20 mg KAF156 developed malaria infection. In contrast, 50 mg KAF156 protected 3/14 participants from infection, and doses of 800, 300, and 100 mg KAF156 protected all subjects against infection. An exposure-response analysis suggested that a 24-hr post-dose concentration of KAF156 of 21·5 ng/mL (90% CI 17.66 to 25.32 ng/mL) would ensure a 95% chance of protection from malaria parasite infection. CONCLUSIONS KAF156 was safe and well tolerated and demonstrated high levels of pre- and post-CHMI protective efficacy.
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Affiliation(s)
- James G Kublin
- Seattle Malaria Clinical Trials Center, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.,Departments of Laboratory Medicine and Microbiology and the Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Sean C Murphy
- Departments of Laboratory Medicine and Microbiology and the Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Janine Maenza
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Annette M Seilie
- Departments of Laboratory Medicine and Microbiology and the Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Jay Prakash Jain
- Novartis Institutes for BioMedical Research, Emeryville, California, USA.,Novartis Healthcare Pvt Ltd, Salarpuria-Sattva Knowledge City Raidurg, Rangareddy District Madhapur/ Hyderabad, Rangareddy, India
| | - David Berger
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Danielle Spera
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
| | - Rong Zhao
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
| | - Rachel L Soon
- Novartis Pharmaceuticals, Health Plaza, East Hanover, NJ
| | - Julie L Czartoski
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | | | - Elizabeth Duke
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Ming Chang
- Departments of Laboratory Medicine and Microbiology and the Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Ashley Vaughan
- Seattle Children's Research Institute, Seattle, Washington, USA
| | | | - F Joel Leong
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
| | - Peter Pertel
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
| | - William T Prince
- Novartis Institutes for BioMedical Research, Emeryville, California, USA
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35
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Goswami D, Betz W, Locham NK, Parthiban C, Brager C, Schäfer C, Camargo N, Nguyen T, Kennedy SY, Murphy SC, Vaughan AM, Kappe SH. A replication-competent late liver stage-attenuated human malaria parasite. JCI Insight 2020; 5:135589. [PMID: 32484795 DOI: 10.1172/jci.insight.135589] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 05/21/2020] [Indexed: 01/06/2023] Open
Abstract
Whole-sporozoite vaccines engender sterilizing immunity against malaria in animal models and importantly, in humans. Gene editing allows for the removal of specific parasite genes, enabling generation of genetically attenuated parasite (GAP) strains for vaccination. Using rodent malaria parasites, we have previously shown that late liver stage-arresting replication-competent (LARC) GAPs confer superior protection when compared with early liver stage-arresting replication-deficient GAPs and radiation-attenuated sporozoites. However, generating a LARC GAP in the human malaria parasite Plasmodium falciparum (P. falciparum) has been challenging. Here, we report the generation and characterization of a likely unprecedented P. falciparum LARC GAP generated by targeted gene deletion of the Mei2 gene: P. falciparum mei2-. Robust exoerythrocytic schizogony with extensive cell growth and DNA replication was observed for P. falciparum mei2- liver stages in human liver-chimeric mice. However, P. falciparum mei2- liver stages failed to complete development and did not form infectious exoerythrocytic merozoites, thereby preventing their transition to asexual blood stage infection. Therefore, P. falciparum mei2- is a replication-competent, attenuated human malaria parasite strain with potentially increased potency, useful for vaccination to protect against P. falciparum malaria infection.
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Affiliation(s)
- Debashree Goswami
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - William Betz
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Navin K Locham
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | | | - Carolyn Brager
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Carola Schäfer
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Nelly Camargo
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Thao Nguyen
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Spencer Y Kennedy
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | | | - Ashley M Vaughan
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA.,Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Stefan Hi Kappe
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA.,Department of Pediatrics, University of Washington, Seattle, Washington, USA
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36
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Owalla TJ, Okurut E, Apungia G, Ojakol B, Lema J, C Murphy S, G Egwang T. Using the Ultrasensitive Alere Plasmodium falciparum Malaria Ag HRP-2 ™ Rapid Diagnostic Test in the Field and Clinic in Northeastern Uganda. Am J Trop Med Hyg 2020; 103:778-784. [PMID: 32602431 DOI: 10.4269/ajtmh.19-0653] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The ultrasensitive Alere Plasmodium falciparum Malaria Ag histidine-rich protein 2 rapid diagnostic test (Alere uRDT, Suwon City, South Korea) is a new diagnostic tool which is more expensive than other malaria rapid diagnostic tests (RDTs) routinely used in Ugandan clinics. The manufacturer recommends testing samples within 2 days and scoring results after 20 minutes, which may be impractical in high-volume resource-poor clinics. We compared testing by the Alere Ag rapid diagnostic test (uRDT), CareStart RDT, microscopy, and an ultrasensitive I8S rRNA quantitative reverse transcription polymerase chain reaction (qRT-PCR) using survey and clinical samples. For the Alere uRDT, we used survey blood samples stored at 4°C for 44 days and for some clinical samples deliberately scored results beyond 20 minutes. The Alere uRDT and qRT-PCR identified asymptomatic parasitemia cases in 56% and 72%, respectively, of survey samples originally scored as negative by the CareStart RDT. Using qRT-PCR as a gold standard, the Alere uRDT was superior to the CareStart RDT in estimating asymptomatic parasite prevalence in a cross-sectional survey (P = 0.007) and in detection of clinically significant malaria; both RDTs were comparable in detecting asymptomatic parasitemia in the clinic (P = 0.599). Scoring Alere uRDT results at 20 minutes produced valid results confirmed by the CareStart RDT, but there was a consistent background; scoring the Alere uRDT beyond 20 minutes produced false-positive results. The Alere uRDT outperformed the CareStart RDT (ACCESSBIO, Somerset, NJ) in a field survey in estimating malaria prevalence and in the clinic for symptomatic malarial illness. It produced reliable results using samples stored at 4°C for 44 days, but test results read beyond 20 minutes were invalid.
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Affiliation(s)
- Tonny Jimmy Owalla
- National Biosafety Biosecurity Coordination Office, Uganda National Health Laboratories Services, Ministry of Health, Kampala, Uganda.,Med Biotech Laboratories, Kampala, Uganda
| | | | | | | | - Jimmy Lema
- Med Biotech Laboratories, Kampala, Uganda
| | - Sean C Murphy
- Departments of Laboratory Medicine and Microbiology, and the Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington
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37
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Schmaler M, Orlova-Fink N, Rutishauser T, Abdulla S, Daubenberger C. Human unconventional T cells in Plasmodium falciparum infection. Semin Immunopathol 2020; 42:265-277. [PMID: 32076813 PMCID: PMC7223888 DOI: 10.1007/s00281-020-00791-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 02/07/2020] [Indexed: 12/22/2022]
Abstract
Malaria is an old scourge of humankind and has a large negative impact on the economic development of affected communities. Recent success in malaria control and reduction of mortality seems to have stalled emphasizing that our current intervention tools need to be complemented by malaria vaccines. Different populations of unconventional T cells such as mucosal-associated invariant T (MAIT) cells, invariant natural killer T (iNKT) cells and γδ T cells are gaining attention in the field of malaria immunology. Significant advances in our basic understanding of unconventional T cell biology in rodent malaria models have been made, however, their roles in humans during malaria are less clear. Unconventional T cells are abundant in skin, gut and liver tissues, and long-lasting expansions and functional alterations were observed upon malaria infection in malaria naïve and malaria pre-exposed volunteers. Here, we review the current understanding of involvement of unconventional T cells in anti-Plasmodium falciparum immunity and highlight potential future research avenues.
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Affiliation(s)
- Mathias Schmaler
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Nina Orlova-Fink
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Tobias Rutishauser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Salim Abdulla
- Ifakara Health Institute, Bagamoyo Clinical Trial Unit, Bagamoyo, Tanzania
| | - Claudia Daubenberger
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland.
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