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Thomson-Luque R, Stabler TC, Fürle K, Silva JC, Daubenberger C. Plasmodium falciparum merozoite surface protein 1 as asexual blood stage malaria vaccine candidate. Expert Rev Vaccines 2024; 23:160-173. [PMID: 38100310 DOI: 10.1080/14760584.2023.2295430] [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: 09/25/2023] [Accepted: 12/12/2023] [Indexed: 12/17/2023]
Abstract
INTRODUCTION Malaria represents a public health challenge in tropical and subtropical regions, and currently deployed control strategies are likely insufficient to drive elimination of malaria. Development and improvement of malaria vaccines might be key to reduce disease burden. Vaccines targeting asexual blood stages of the parasite have shown limited efficacy when studied in human trials conducted over the past decades. AREAS COVERED Vaccine candidates based on the merozoite surface protein 1 (MSP1) were initially envisioned as one of the most promising approaches to provide immune protection against asexual blood-stage malaria. Successful immunization studies in monkey involved the use of the full-length MSP1 (MSP1FL) as vaccine construct. Vaccines using MSP1FL for immunization have the potential benefit of including numerous conserved B-cell and T-cell epitopes. This could result in improved parasite strain-transcending, protective immunity in the field. We review outcomes of clinical trials that utilized a variety of MSP1 constructs and formulations, including MSP1FL, either alone or in combination with other antigens, in both animal models and humans. EXPERT OPINION Novel approaches to analyze breadth and magnitude of effector functions of MSP1-targeting antibodies in volunteers undergoing experimental vaccination and controlled human malaria infection will help to define correlates of protective immunity.
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Affiliation(s)
- Richard Thomson-Luque
- Centre for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
- Sumaya-Biotech GmbH & Co. KG Heidelberg, Germany
| | - Thomas C Stabler
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
- University of Basel Basel, Switzerland
- Swiss Tropical and Public Health Institute Allschwil, Switzerland
| | - Kristin Fürle
- Centre for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Joana C Silva
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
- Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade NOVA de Lisboa (GHTM IHMT, UNL), Lisbon, Portugal
| | - Claudia Daubenberger
- University of Basel Basel, Switzerland
- Swiss Tropical and Public Health Institute Allschwil, Switzerland
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Rosenkranz M, Fürle K, Hibbert J, Ulmer A, Ali A, Giese T, Blank A, Haefeli WE, Böhnlein E, Lanzer M, Thomson-Luque R. Multifunctional IgG/IgM antibodies and cellular cytotoxicity are elicited by the full-length MSP1 SumayaVac-1 malaria vaccine. NPJ Vaccines 2023; 8:112. [PMID: 37558673 PMCID: PMC10412566 DOI: 10.1038/s41541-023-00701-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 06/27/2023] [Indexed: 08/11/2023] Open
Abstract
Radical control of malaria likely requires a vaccine that targets both the asymptomatic liver stages and the disease-causing blood stages of the human malaria parasite Plasmodium falciparum. While substantial progress has been made towards liver stage vaccines, the development of a blood stage vaccine is lagging behind. We have recently conducted a first-in-human clinical trial to evaluate the safety and immunogenicity of the recombinant, full-length merozoite surface protein 1 (MSP1FL) formulated with GLA-SE as adjuvant. Here, we show that the vaccine, termed SumayaVac-1, elicited both a humoral and cellular immune response as well as a recall T cell memory. The induced IgG and IgM antibodies were able to stimulate various Fc-mediated effector mechanisms associated with protection against malaria, including phagocytosis, release of reactive oxygen species, production of IFN-γ as well as complement activation and fixation. The multifunctional activity of the humoral immune response remained for at least 6 months after vaccination and was comparable to that of naturally acquired anti-MSP1 antibodies from semi-immune adults from Kenya. We further present evidence of SumayaVac-1 eliciting a recallable cellular cytotoxicity by IFN-γ producing CD8+ T cells. Our study revitalizes MSP1FL as a relevant blood stage vaccine candidate and warrants further evaluation of SumayaVac-1 in a phase II efficacy trial.
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Affiliation(s)
- Micha Rosenkranz
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Kristin Fürle
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Julia Hibbert
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Anne Ulmer
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Arin Ali
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Thomas Giese
- Institute for Immunology, Heidelberg University Hospital and German Center for Infection Research (DZIF), Heidelberg, Germany
| | - Antje Blank
- Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Walter E Haefeli
- Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Heidelberg, Germany
| | | | - Michael Lanzer
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Richard Thomson-Luque
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany.
- Sumaya-Biotech GmbH & Co. KG, Heidelberg, Germany.
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Blank A, Fürle K, Jäschke A, Mikus G, Lehmann M, Hüsing J, Heiss K, Giese T, Carter D, Böhnlein E, Lanzer M, Haefeli WE, Bujard H. Immunization with full-length Plasmodium falciparum merozoite surface protein 1 is safe and elicits functional cytophilic antibodies in a randomized first-in-human trial. NPJ Vaccines 2020; 5:10. [PMID: 32025341 PMCID: PMC6994672 DOI: 10.1038/s41541-020-0160-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 01/14/2020] [Indexed: 12/20/2022] Open
Abstract
A vaccine remains a priority in the global fight against malaria. Here, we report on a single-center, randomized, double-blind, placebo and adjuvant-controlled, dose escalation phase 1a safety and immunogenicity clinical trial of full-length Plasmodium falciparum merozoite surface protein 1 (MSP1) in combination with GLA-SE adjuvant. Thirty-two healthy volunteers were vaccinated at least three times with MSP1 plus adjuvant, adjuvant alone, or placebo (24:4:4) to evaluate the safety and immunogenicity. MSP1 was safe, well tolerated and immunogenic, with all vaccinees sero-converting independent of the dose. The MSP1-specific IgG and IgM titers persisted above levels found in malaria semi-immune humans for at least 6 months after the last immunization. The antibodies were variant- and strain-transcending and stimulated respiratory activity in granulocytes. Furthermore, full-length MSP1 induced memory T-cells. Our findings encourage challenge studies as the next step to evaluate the efficacy of full-length MSP1 as a vaccine candidate against falciparum malaria (EudraCT 2016-002463-33).
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Affiliation(s)
- Antje Blank
- Klinische Pharmakologie und Pharmakoepidemiologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Kristin Fürle
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Anja Jäschke
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Gerd Mikus
- Klinische Pharmakologie und Pharmakoepidemiologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Monika Lehmann
- Koordinierungszentrum für Klinische Studien (KKS), Universitätsklinikum Heidelberg, Im Neuenheimer Feld 130.3, 69120 Heidelberg, Germany
| | - Johannes Hüsing
- Koordinierungszentrum für Klinische Studien (KKS), Universitätsklinikum Heidelberg, Im Neuenheimer Feld 130.3, 69120 Heidelberg, Germany
| | - Kirsten Heiss
- PEPperPRINT GmbH, Rischerstrasse 12, 69123 Heidelberg, Germany
| | - Thomas Giese
- Institut für Immunologie, Universitätsklinikum Heidelberg und Deutsches Zentrum für Infektionsforschung (DZIF) Standort Heidelberg, Im Neuenheimer Feld 305, 69120 Heidelberg, Germany
| | - Darrick Carter
- PAI Life Sciences, 1616 Eastlake Ave E, Suite 550, Seattle, WA 98102 USA
| | - Ernst Böhnlein
- Sumaya Biotech GmbH & Co. KG, Im Neuenheimer Feld 582, 69120 Heidelberg, Germany
| | - Michael Lanzer
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Walter E. Haefeli
- Klinische Pharmakologie und Pharmakoepidemiologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Hermann Bujard
- Sumaya Biotech GmbH & Co. KG, Im Neuenheimer Feld 582, 69120 Heidelberg, Germany
- Zentrum für Molekulare Biologie Heidelberg, Universität Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
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Taghavian O, Jain A, Joyner CJ, Ketchum S, Nakajima R, Jasinskas A, Liang L, Fong R, King C, Greenhouse B, Murphy M, Bailey J, Galinski MR, Barnwell JW, Plowe CV, Davies DH, Felgner PL. Antibody Profiling by Proteome Microarray with Multiplex Isotype Detection Reveals Overlap between Human and Aotus nancymaae Controlled Malaria Infections. Proteomics 2019; 18. [PMID: 29266845 DOI: 10.1002/pmic.201700277] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 11/21/2017] [Indexed: 12/13/2022]
Abstract
The development of vaccines against malaria and serodiagnostic tests for detecting recent exposure requires tools for antigen discovery and suitable animal models. The protein microarray is a high-throughput, sample sparing technique, with applications in infectious disease research, clinical diagnostics, epidemiology, and vaccine development. We recently demonstrated Qdot-based indirect immunofluorescence together with portable optical imager ArrayCAM using single isotype detection could replicate data using the conventional laser confocal scanner system. We developed a multiplexing protocol for simultaneous detection of IgG, IgA, and IgM and compared samples from a controlled human malaria infection model with those from controlled malaria infections of Aotus nancymaae, a widely used non-human primate model of human malaria. IgG profiles showed the highest concordance in number of reactive antigens; thus, of the 139 antigens recognized by human IgG antibody, 111 were also recognized by Aotus monkeys. Interestingly, IgA profiles were largely non-overlapping. Finally, on the path toward wider deployment of the portable platform, we show excellent correlations between array data obtained in five independent laboratories around the United States using the multiplexing protocol (R2 : 0.60-0.92). This study supports the use of this platform for wider deployment, particularly in endemic areas where such a tool will have the greatest impact on global human health.
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Affiliation(s)
- Omid Taghavian
- Department of Medicine, Division of Infectious Diseases, University of California Irvine, Irvine, CA, USA
| | - Aarti Jain
- Department of Medicine, Division of Infectious Diseases, University of California Irvine, Irvine, CA, USA
| | - Chester J Joyner
- International Center for Malaria Research, Education and Development, Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA
| | | | - Rie Nakajima
- Department of Medicine, Division of Infectious Diseases, University of California Irvine, Irvine, CA, USA
| | - Algis Jasinskas
- Department of Medicine, Division of Infectious Diseases, University of California Irvine, Irvine, CA, USA
| | - Li Liang
- Department of Medicine, Division of Infectious Diseases, University of California Irvine, Irvine, CA, USA
| | - Rich Fong
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA
| | - Christopher King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Maxwell Murphy
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Jason Bailey
- Division of Infectious Diseases, Department of Medicine, Emory University, Atlanta, GA, USA
| | - Mary R Galinski
- International Center for Malaria Research, Education and Development, Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA.,Division of Infectious Diseases, Department of Medicine, Emory University, Atlanta, GA, USA
| | - John W Barnwell
- Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Christopher V Plowe
- Howard Hughes Medical Institute/Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA
| | - D Huw Davies
- Department of Medicine, Division of Infectious Diseases, University of California Irvine, Irvine, CA, USA
| | - Philip L Felgner
- Department of Medicine, Division of Infectious Diseases, University of California Irvine, Irvine, CA, USA
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Crosby FL, Lundgren AM, Hoffman C, Pascual DW, Barbet AF. VirB10 vaccination for protection against Anaplasma phagocytophilum. BMC Microbiol 2018; 18:217. [PMID: 30563470 PMCID: PMC6299599 DOI: 10.1186/s12866-018-1346-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 11/16/2018] [Indexed: 12/18/2022] Open
Abstract
Background Human granulocytic anaplasmosis (HGA) is a tick-borne disease caused by the etiologic agent Anaplasma phagocytophilum. HGA was designated a nationally notifiable disease in the United States in 1998. Currently there are no vaccines available against HGA. Conserved membrane proteins that are subdominant in Anaplasma species, such as VirB9 and VirB10, may represent better vaccine targets than the variable immunodominant surface proteins. VirB9 and VirB10 are constituents of the Type 4 secretion system (T4SS) that is conserved amongst many intracellular bacteria and performs essential functions for invasion and survival in host cells. Results Immunogenicity and contribution to protection, provided after intramuscular vaccination of plasmid DNA encoding VirB9-1, VirB9-2, and VirB10 followed by inoculation of homologous recombinant proteins, in a prime-boost immunization strategy was evaluated in a murine model of HGA. Recombinant VirB9-1-, VirB9-2-, and VirB10-vaccinated mice developed antibody responses that specifically reacted with A. phagocytophilum organisms. However, only the mice vaccinated with VirB10 developed a significant increase in IFN-γ CD4+ T cells and partial protection against challenge with A. phagocytophilum. Conclusions This work provides evidence that A. phagocytophilum T4SS VirB10 is partially protective in a murine model against infection in an IFN-γ-dependent fashion and suggests that this protein may be a potential vaccine candidate against this and possibly other pathogenic bacteria with a T4SS.
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Affiliation(s)
- Francy L Crosby
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, 2015 SW 16th Avenue, Gainesville, FL, 32608, USA.
| | - Anna M Lundgren
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, 2015 SW 16th Avenue, Gainesville, FL, 32608, USA
| | - Carol Hoffman
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, 2015 SW 16th Avenue, Gainesville, FL, 32608, USA
| | - David W Pascual
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, 2015 SW 16th Avenue, Gainesville, FL, 32608, USA
| | - Anthony F Barbet
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, 2015 SW 16th Avenue, Gainesville, FL, 32608, USA
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Ghoshal S, Gajendra P, Datta Kanjilal S, Mitra M, Sengupta S. Diversity analysis of MSP1 identifies conserved epitope organization in block 2 amidst high sequence variability in Indian Plasmodium falciparum isolates. Malar J 2018; 17:447. [PMID: 30509263 PMCID: PMC6276175 DOI: 10.1186/s12936-018-2592-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 11/23/2018] [Indexed: 02/02/2023] Open
Abstract
Background Despite its immunogenicity, the polymorphic nature of merozoite surface protein 1, an important vaccine candidate for Plasmodium falciparum malaria, remains a concern. This study analyses the impact of genetic variability and parasite population structure on epitope organization of different MSP1 segments. Methods Altogether 98 blood samples collected from P. falciparum infected mild and severe malaria patients of Chhattisgarh and West Bengal were used to sequence regions encoding block 2 and MSP1-19 of msp1. Sequences were analysed using MEGA7, DnaSPv5, Arlequin3.5 and BepiPred. Results All three major MSP1 block 2 allele families namely K1, MAD20 and RO33 were detected in the samples and they together resulted in 41 indel variants. Chhattisgarh samples displayed an average MOI of 2.07 ± 1.59 which was higher in mild malaria and in age group < 18 years. Ultra-structure of block 2 alleles revealed that mutation and repeat expansion were two major mechanisms responsible for allelic variability of K1 and MAD20. Regions flanking block 2 were highly variable in Chhattisgarh with average mismatch differences (k) ranging from 1.198 to 5.156 for three families. In contrast, region encompassing MSP1-19 exhibited limited heterogeneity (kChhattisgarh = 1.45, kWest Bengal = 1.363). Of the 50 possible B cell linear epitopes predicted from block 2 variants, 94.9% (131 of 138) of the parasites could be represented by three conserved antigens. Conclusions Present data indicates that natural selection and transmission intensity jointly play a role in controlling allelic diversity of MSP1 in Indian parasite isolates. Despite remarkable genetic variability, a limited number of predominant and conserved epitopes are present in Indian parasite isolates reinstating the importance of MSP1 as a promising malaria vaccine candidate. Electronic supplementary material The online version of this article (10.1186/s12936-018-2592-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sharmistha Ghoshal
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, West Bengal, 700 019, India
| | - Pragya Gajendra
- School of Studies in Anthropology, Pt. Ravishankar Shukla University, Raipur, Chhattisgarh, 492010, India
| | - Sumana Datta Kanjilal
- Department of Pediatric Medicine, Institute of Post Graduate Medical Education & Research, Kolkata, West Bengal, India
| | - Mitashree Mitra
- School of Studies in Anthropology, Pt. Ravishankar Shukla University, Raipur, Chhattisgarh, 492010, India
| | - Sanghamitra Sengupta
- Department of Biochemistry, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, West Bengal, 700 019, India.
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Aspeling-Jones H, Conway DJ. An expanded global inventory of allelic variation in the most extremely polymorphic region of Plasmodium falciparum merozoite surface protein 1 provided by short read sequence data. Malar J 2018; 17:345. [PMID: 30285849 PMCID: PMC6167803 DOI: 10.1186/s12936-018-2475-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 09/04/2018] [Indexed: 12/15/2022] Open
Abstract
Background Within Plasmodium falciparum merozoite surface protein 1 (MSP1), the N-terminal block 2 region is a highly polymorphic target of naturally acquired antibody responses. The antigenic diversity is determined by complex repeat sequences as well as non-repeat sequences, grouping into three major allelic types that appear to be maintained within populations by natural selection. Within these major types, many distinct allelic sequences have been described in different studies, but the extent and significance of the diversity remains unresolved. Methods To survey the diversity more extensively, block 2 allelic sequences in the msp1 gene were characterized in 2400 P. falciparum infection isolates with whole genome short read sequence data available from the Pf3K project, and compared with the data from previous studies. Results Mapping the short read sequence data in the 2400 isolates to a reference library of msp1 block 2 allelic sequences yielded 3815 allele scores at the level of major allelic family types, with 46% of isolates containing two or more of these major types. Overall frequencies were similar to those previously reported in other samples with different methods, the K1-like allelic type being most common in Africa, MAD20-like most common in Southeast Asia, and RO33-like being the third most abundant type in each continent. The rare MR type, formed by recombination between MAD20-like and RO33-like alleles, was only seen in Africa and very rarely in the Indian subcontinent but not in Southeast Asia. A combination of mapped short read assembly approaches enabled 1522 complete msp1 block 2 sequences to be determined, among which there were 363 different allele sequences, of which 246 have not been described previously. In these data, the K1-like msp1 block 2 alleles are most diverse and encode 225 distinct amino acid sequences, compared with 123 different MAD20-like, 9 RO33-like and 6 MR type sequences. Within each of the major types, the different allelic sequences show highly skewed geographical distributions, with most of the more common sequences being detected in either Africa or Asia, but not in both. Conclusions Allelic sequences of this extremely polymorphic locus have been derived from whole genome short read sequence data by mapping to a reference library followed by assembly of mapped reads. The catalogue of sequence variation has been greatly expanded, so that there are now more than 500 different msp1 block 2 allelic sequences described. This provides an extensive reference for molecular epidemiological genotyping and sequencing studies, and potentially for design of a multi-allelic vaccine. Electronic supplementary material The online version of this article (10.1186/s12936-018-2475-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Harvey Aspeling-Jones
- Pathogen Molecular Biology Department, School of Hygiene and Tropical Medicine London, Keppel St, London, WC1E 7HT, UK.
| | - David J Conway
- Pathogen Molecular Biology Department, School of Hygiene and Tropical Medicine London, Keppel St, London, WC1E 7HT, UK.
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Wijayalath W, Majji S, Villasante EF, Brumeanu TD, Richie TL, Casares S. Humanized HLA-DR4.RagKO.IL2RγcKO.NOD (DRAG) mice sustain the complex vertebrate life cycle of Plasmodium falciparum malaria. Malar J 2014; 13:386. [PMID: 25266106 PMCID: PMC4197321 DOI: 10.1186/1475-2875-13-386] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 09/18/2014] [Indexed: 12/28/2022] Open
Abstract
Background Malaria is a deadly infectious disease affecting millions of people in tropical and sub-tropical countries. Among the five species of Plasmodium parasites that infect humans, Plasmodium falciparum accounts for the highest morbidity and mortality associated with malaria. Since humans are the only natural hosts for P. falciparum, the lack of convenient animal models has hindered the understanding of disease pathogenesis and prompted the need of testing anti-malarial drugs and vaccines directly in human trials. Humanized mice hosting human cells represent new pre-clinical models for infectious diseases that affect only humans. In this study, the ability of human-immune-system humanized HLA-DR4.RagKO.IL2RγcKO.NOD (DRAG) mice to sustain infection with P. falciparum was explored. Methods Four week-old DRAG mice were infused with HLA-matched human haematopoietic stem cells (HSC) and examined for reconstitution of human liver cells and erythrocytes. Upon challenge with infectious P. falciparum sporozoites (NF54 strain) humanized DRAG mice were examined for liver stage infection, blood stage infection, and transmission to Anopheles stephensi mosquitoes. Results Humanized DRAG mice reconstituted human hepatocytes, Kupffer cells, liver endothelial cells, and erythrocytes. Upon intravenous challenge with P. falciparum sporozoites, DRAG mice sustained liver to blood stage infection (average 3–5 parasites/microlitre blood) and allowed transmission to An. stephensi mosquitoes. Infected DRAG mice elicited antibody and cellular responses to the blood stage parasites and self-cured the infection by day 45 post-challenge. Conclusions DRAG mice represent the first human-immune-system humanized mouse model that sustains the complex vertebrate life cycle of P. falciparum without the need of exogenous injection of human hepatocytes/erythrocytes or P. falciparum parasite adaptation. The ability of DRAG mice to elicit specific human immune responses to P. falciparum parasites may help deciphering immune correlates of protection and to identify protective malaria antigens.
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Affiliation(s)
| | | | | | | | | | - Sofia Casares
- US Military Malaria Vaccine Program, Naval Medical Research Center/Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA.
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