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O'Flaherty K, Roe M, Fowkes FJ. The role of naturally acquired antimalarial antibodies in subclinical
Plasmodium
spp. infection. J Leukoc Biol 2022; 111:1097-1105. [PMID: 35060185 PMCID: PMC9303632 DOI: 10.1002/jlb.5mr1021-537r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/09/2021] [Indexed: 12/17/2022] Open
Affiliation(s)
- Katherine O'Flaherty
- Disease Elimination Program Burnet Institute for Medical Research and Public Health Melbourne Australia
| | - Merryn Roe
- Disease Elimination Program Burnet Institute for Medical Research and Public Health Melbourne Australia
- School of Public Health and Preventive Medicine Monash University Melbourne Australia
| | - Freya J.I. Fowkes
- Disease Elimination Program Burnet Institute for Medical Research and Public Health Melbourne Australia
- School of Public Health and Preventive Medicine Monash University Melbourne Australia
- Centre for Epidemiology and Biostatistics Melbourne School of Population and Global Health, The University of Melbourne Melbourne Australia
- Department of Infectious Disease Monash University Melbourne Australia
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2
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Rachmania S, Sulistyaningsih E, Ratna Dewi AAI. Recombinant DBL2β-PfEMP1 of the Indonesian Plasmodium falciparum induces immune responses in Wistar rats. J Taibah Univ Med Sci 2021; 16:422-430. [PMID: 34140870 PMCID: PMC8178645 DOI: 10.1016/j.jtumed.2020.12.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 12/12/2020] [Accepted: 12/17/2020] [Indexed: 11/21/2022] Open
Abstract
OBJECTIVES The Duffy binding-like (DBL) domain of the Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) is reportedly responsible for the pathophysiology of cerebral malaria. People living in endemic malaria areas possess specific antibodies against PfEMP1 and elicit immune responses to control the severity of malaria infection. Therefore, PfEMP1 may be a potential protein-based vaccine candidate. This study aimed to explore the humoral and cellular immune responses induced by the recombinant DBL2β-PfEMP1 obtained from the Indonesian P. falciparum isolate. METHODS The recombinant protein was expressed in Escherichia coli BL21(DE3) as soluble and insoluble fractions, and this protein was purified using affinity chromatography before administration as a subcutaneous injection in Wistar rats on days 1, 21, and 42. Sera were harvested 14 days after the second and third injections to determine the titre of IgG and the concentration of CD4+ cells using the enzyme linked immunosorbent assay (ELISA). RESULTS The IgG titre and the CD4+ cell concentration were found to be increased after the second and third injections. The Mann-Whitney test results showed a significant difference between the control and treatment groups for both the IgG and CD4+ cells (p = 0.001 and p = 0.000, respectively). Western blotting results indicated the presence of a specific antibody against the recombinant DBL2β-PfEMP1. CONCLUSIONS The recombinant DBL2β-PfEMP1 of the Indonesian P. falciparum isolate could induce humoral and cellular immune responses. Further studies on IgG exerting inhibitory effects and the role of CD4+ cells and their association with other effector cells are essential to determine the efficacy of DBL2β-PfEMP1 and its potential application as a peptide-based malaria vaccine candidate.
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Affiliation(s)
- Sheilla Rachmania
- Department of Histology, Faculty of Medicine, University of Jember, Indonesia
| | - Erma Sulistyaningsih
- Department of Parasitology, Faculty of Medicine, University of Jember, Indonesia
| | - Anak Agung I. Ratna Dewi
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Jember, Indonesia
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3
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Oduma CO, Ogolla S, Atieli H, Ondigo BN, Lee MC, Githeko AK, Dent AE, Kazura JW, Yan G, Koepfli C. Increased investment in gametocytes in asymptomatic Plasmodium falciparum infections in the wet season. BMC Infect Dis 2021; 21:44. [PMID: 33422001 PMCID: PMC7797145 DOI: 10.1186/s12879-020-05761-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 12/30/2020] [Indexed: 11/10/2022] Open
Abstract
Background Transmission stemming from asymptomatic infections is increasingly being recognized as a threat to malaria elimination. In many regions, malaria transmission is seasonal. It is not well understood whether Plasmodium falciparum modulates its investment in transmission to coincide with seasonal vector abundance. Methods We sampled 1116 asymptomatic individuals in the wet season, when vectors are abundant, and 1743 in the dry season, in two sites in western Kenya, representing different transmission intensities (Chulaimbo, moderate transmission, and Homa Bay, low transmission). Blood samples were screened for P. falciparum by qPCR, and gametocytes by pfs25 RT-qPCR. Results Parasite prevalence by qPCR was 27.1% (Chulaimbo, dry), 48.2% (Chulaimbo, wet), 9.4% (Homabay, dry), and 7.8% (Homabay, wet). Mean parasite densities did not differ between seasons (P = 0.562). pfs25 transcripts were detected in 119/456 (26.1%) of infections. In the wet season, fewer infections harbored detectable gametocytes (22.3% vs. 33.8%, P = 0.009), but densities were 3-fold higher (wet: 3.46 transcripts/uL, dry: 1.05 transcripts/uL, P < 0.001). In the dry season, 4.0% of infections carried gametocytes at moderate-to-high densities likely infective (> 1 gametocyte per 2 uL blood), compared to 7.9% in the wet season. Children aged 5–15 years harbored 76.7% of infections with gametocytes at moderate-to-high densities. Conclusions Parasites increase their investment in transmission in the wet season, reflected by higher gametocyte densities. Despite increased gametocyte densities, parasite density remained similar across seasons and were often below the limit of detection of microscopy or rapid diagnostic test, thus a large proportion of infective infections would escape population screening in the wet season. Seasonal changes of gametocytemia in asymptomatic infections need to be considered when designing malaria control measures. Supplementary Information The online version contains supplementary material available at 10.1186/s12879-020-05761-6.
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Affiliation(s)
- Colins O Oduma
- Department of Biochemistry and Molecular Biology, Egerton University, P. O Box 536, Nakuru, 20115, Kenya.,Kenya Medical Research Institute/Centre for Global Health Research, P. O Box 1578, Kisumu, 40100, Kenya
| | - Sidney Ogolla
- Kenya Medical Research Institute/Centre for Global Health Research, P. O Box 1578, Kisumu, 40100, Kenya
| | - Harrysone Atieli
- School of Public Health, Maseno University, P. O Box 3275, Maseno, 40100, Kenya.,International Center of Excellence for Malaria Research, P. O Box 199, Homa Bay, 40300, Kenya
| | - Bartholomew N Ondigo
- Department of Biochemistry and Molecular Biology, Egerton University, P. O Box 536, Nakuru, 20115, Kenya.,Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institute Health, Bethesda, MD, 20892, USA
| | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California, Irvine, CA, 92697, USA
| | - Andrew K Githeko
- International Center of Excellence for Malaria Research, P. O Box 199, Homa Bay, 40300, Kenya
| | - Arlene E Dent
- Case Western Reserve University, Center for Global Health and Diseases, LC 4983, Cleveland, OH, 44106, USA
| | - James W Kazura
- Case Western Reserve University, Center for Global Health and Diseases, LC 4983, Cleveland, OH, 44106, USA
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California, Irvine, CA, 92697, USA
| | - Cristian Koepfli
- Eck Institute for Global Health and Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556-0369, USA.
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4
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Carpio VH, Aussenac F, Puebla-Clark L, Wilson KD, Villarino AV, Dent AL, Stephens R. T Helper Plasticity Is Orchestrated by STAT3, Bcl6, and Blimp-1 Balancing Pathology and Protection in Malaria. iScience 2020; 23:101310. [PMID: 32634740 PMCID: PMC7339051 DOI: 10.1016/j.isci.2020.101310] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 05/20/2020] [Accepted: 06/19/2020] [Indexed: 12/16/2022] Open
Abstract
Hybrid Th1/Tfh cells (IFN-γ+IL-21+CXCR5+) predominate in response to several persistent infections. In Plasmodium chabaudi infection, IFN-γ+ T cells control parasitemia, whereas antibody and IL-21+Bcl6+ T cells effect final clearance, suggesting an evolutionary driver for the hybrid population. We found that CD4-intrinsic Bcl6, Blimp-1, and STAT3 coordinately regulate expression of the Th1 master regulator T-bet, supporting plasticity of CD4 T cells. Bcl6 and Blimp-1 regulate CXCR5 levels, and T-bet, IL-27Rα, and STAT3 modulate cytokines in hybrid Th1/Tfh cells. Infected mice with STAT3 knockout (KO) T cells produced less antibody and more Th1-like IFN-γ+IL-21−CXCR5lo effector and memory cells and were protected from re-infection. Conversely, T-bet KO mice had reduced Th1-bias upon re-infection and prolonged secondary parasitemia. Therefore, each feature of the CD4 T cell population phenotype is uniquely regulated in this persistent infection, and the cytokine profile of memory T cells can be modified to enhance the effectiveness of the secondary response. Plasmodium infection induces a CXCR5+IFN-γ+IL-21+ hybrid Th1/Tfh cell subset STAT3/WSX-1, T-bet, Bcl6, and Blimp-1 regulate different aspects of Th1/Tfh phenotype T cell-intrinsic STAT3 regulates degree of Th1 commitment of hybrid Th1/Tfh Shifting the plastic response toward Th1-like cells promotes resistance from reinfection
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Affiliation(s)
- Victor H Carpio
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555-0435, USA
| | - Florentin Aussenac
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0435, USA
| | - Lucinda Puebla-Clark
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0435, USA
| | - Kyle D Wilson
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555-0435, USA
| | - Alejandro V Villarino
- Molecular Immunology and Inflammation Branch, National Institute of Arthritis, Metabolic, and Skin Diseases, National Institutes of Health, Bethesda, MD 20892-1674, USA
| | - Alexander L Dent
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Robin Stephens
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555-0435, USA; Department of Internal Medicine, Division of Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0435, USA.
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5
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Gbedande K, Carpio VH, Stephens R. Using two phases of the CD4 T cell response to blood-stage murine malaria to understand regulation of systemic immunity and placental pathology in Plasmodium falciparum infection. Immunol Rev 2020; 293:88-114. [PMID: 31903675 PMCID: PMC7540220 DOI: 10.1111/imr.12835] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 12/08/2019] [Accepted: 12/09/2019] [Indexed: 02/06/2023]
Abstract
Plasmodium falciparum infection and malaria remain a risk for millions of children and pregnant women. Here, we seek to integrate knowledge of mouse and human T helper cell (Th) responses to blood-stage Plasmodium infection to understand their contribution to protection and pathology. Although there is no complete Th subset differentiation, the adaptive response occurs in two phases in non-lethal rodent Plasmodium infection, coordinated by Th cells. In short, cellular immune responses limit the peak of parasitemia during the first phase; in the second phase, humoral immunity from T cell-dependent germinal centers is critical for complete clearance of rapidly changing parasite. A strong IFN-γ response kills parasite, but an excess of TNF compared with regulatory cytokines (IL-10, TGF-β) can cause immunopathology. This common pathway for pathology is associated with anemia, cerebral malaria, and placental malaria. These two phases can be used to both understand how the host responds to rapidly growing parasite and how it attempts to control immunopathology and variation. This dual nature of T cell immunity to Plasmodium is discussed, with particular reference to the protective nature of the continuous generation of effector T cells, and the unique contribution of effector memory T cells.
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Affiliation(s)
- Komi Gbedande
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas
| | - Victor H Carpio
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas
| | - Robin Stephens
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas
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Kimenyi KM, Wamae K, Ochola-Oyier LI. Understanding P. falciparum Asymptomatic Infections: A Proposition for a Transcriptomic Approach. Front Immunol 2019; 10:2398. [PMID: 31681289 PMCID: PMC6803459 DOI: 10.3389/fimmu.2019.02398] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 09/25/2019] [Indexed: 12/11/2022] Open
Abstract
Malaria is still a significant public health burden in the tropics. Infection with malaria causing parasites results in a wide range of clinical disease presentations, from severe to uncomplicated or mild, and in the poorly understood asymptomatic infections. The complexity of asymptomatic infections is due to the intricate interplay between factors derived from the human host, parasite, and environment. Asymptomatic infections often go undetected and provide a silent natural reservoir that sustains malaria transmission. This creates a major obstacle for malaria control and elimination efforts. Numerous studies have tried to characterize asymptomatic infections, unanimously revealing that host immunity is the underlying factor in the maintenance of these infections and in the risk of developing febrile malaria infections. An in-depth understanding of how host immunity and parasite factors interact to cause malaria disease tolerance is thus required. This review primarily focuses on understanding anti-inflammatory and pro-inflammatory responses to asymptomatic infections in malaria endemic areas, to present the view that it is potentially the shift in host immunity toward an anti-inflammatory profile that maintains asymptomatic infections after multiple exposures to malaria. Conversely, symptomatic infections are skewed toward a pro-inflammatory immune profile. Moreover, we propose that these infections can be better interrogated using next generation sequencing technologies, in particular RNA sequencing (RNA-seq), to investigate the immune system using the transcriptome sampled during a clearly defined asymptomatic infection.
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Affiliation(s)
- Kelvin M Kimenyi
- KEMRI-Wellcome Trust Research Programme, CGMRC, Kilifi, Kenya.,Centre for Biotechnology and Bioinformatics, University of Nairobi, Nairobi, Kenya
| | - Kevin Wamae
- KEMRI-Wellcome Trust Research Programme, CGMRC, Kilifi, Kenya
| | - Lynette Isabella Ochola-Oyier
- KEMRI-Wellcome Trust Research Programme, CGMRC, Kilifi, Kenya.,Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya
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Thái TL, Jun H, Lee J, Kang JM, Lê HG, Lin K, Thant KZ, Sohn WM, Kim TS, Na BK. Genetic diversity of merozoite surface protein-1 C-terminal 42 kDa of Plasmodium falciparum (PfMSP-1 42) may be greater than previously known in global isolates. Parasit Vectors 2018; 11:455. [PMID: 30081943 PMCID: PMC6080494 DOI: 10.1186/s13071-018-3027-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/20/2018] [Indexed: 11/16/2022] Open
Abstract
Background The C-terminal 42 kDa region of merozoite surface protein-1 of Plasmodium falciparum (PfMSP-142) is the target of an immune response. It has been recognised as one of the promising candidate antigens for a blood-stage malaria vaccine. Genetic structure of PfMSP-142 has been considered to be largely conserved in the P. falciparum population. However, only limited information is currently available. This study aimed to analyse genetic diversity and the effect of natural selection on PfMSP-142 among the Myanmar P. falciparum population and compare them with publicly available PfMSP-142 from global P. falciparum populations. Methods A total of 69 P. falciparum clinical isolates collected from Myanmar malaria patients in Upper Myanmar in 2015 were used. The PfMSP-142 region was amplified by polymerase chain reaction, cloned and sequenced. Genetic structure and natural selection of this region were analysed using MEGA4 and DnaSP programs. Polymorphic nature and natural selection in global PfMSP-142 were also investigated. Results All three allele types (MAD20, K1, and RO33) of PfMSP-142 were identified in Myanmar isolates of P. falciparum. Myanmar PfMSP-142 displayed genetic diversity. Most polymorphisms were scattered in blocks 16 and 17. Polymorphisms observed in Myanmar PfMSP-142 showed a similar pattern to those of global PfMSP-142; however, they were not identical to each other. Genetic diversity of Myanmar PfMSP-142 was relatively lower than that of PfMSP-142 from different geographical regions. Evidence of natural selection and recombination were found. Comparative analysis of genetic polymorphism and natural selection in the global PfMSP-142 population suggested that this region was not tightly conserved in global PfMSP-142 as previously thought and is under the complicated influence of natural selection and recombination. Conclusions Global PfMSP-142 revealed limited, but non-negligible, genetic diversity by allele types and geographical origins. Complicated natural selection and potential recombination might have occurred in global PfMSP-142. Comprehensive monitoring of genetic diversity for global PfMSP-142 would be needed to better understand the polymorphic nature and evolutionary aspect of PfMSP-142 in the global P. falciparum population. More thought would be necessary for designing a vaccine based on PfMSP-142. Electronic supplementary material The online version of this article (10.1186/s13071-018-3027-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Thị Lam Thái
- Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju, 52727, Republic of Korea.,BK21Plus Team for Anti-aging Biotechnology and Industry, Department of Convergence Medical Science, Gyeongsang National University, Jinju, 52727, Republic of Korea
| | - Hojong Jun
- Department of Tropical Medicine, and Inha Research Institute for Medical Sciences, Inha University College of Medicine, Incheon, 22212, Republic of Korea
| | - Jinyoung Lee
- Department of Tropical Medicine, and Inha Research Institute for Medical Sciences, Inha University College of Medicine, Incheon, 22212, Republic of Korea
| | - Jung-Mi Kang
- Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju, 52727, Republic of Korea.,BK21Plus Team for Anti-aging Biotechnology and Industry, Department of Convergence Medical Science, Gyeongsang National University, Jinju, 52727, Republic of Korea
| | - Hương Giang Lê
- Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju, 52727, Republic of Korea.,BK21Plus Team for Anti-aging Biotechnology and Industry, Department of Convergence Medical Science, Gyeongsang National University, Jinju, 52727, Republic of Korea
| | - Khin Lin
- Department of Medical Research Pyin Oo Lwin Branch, Pyin Oo Lwin, Myanmar
| | - Kyaw Zin Thant
- Department of Medical Research, Ministry of Health and Sports, Yangon, Myanmar
| | - Woon-Mok Sohn
- Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju, 52727, Republic of Korea
| | - Tong-Soo Kim
- Department of Tropical Medicine, and Inha Research Institute for Medical Sciences, Inha University College of Medicine, Incheon, 22212, Republic of Korea.
| | - Byoung-Kuk Na
- Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju, 52727, Republic of Korea. .,BK21Plus Team for Anti-aging Biotechnology and Industry, Department of Convergence Medical Science, Gyeongsang National University, Jinju, 52727, Republic of Korea.
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Interferon- γ and Interleukin-10 Responses during Clinical Malaria Episodes in Infants Aged 0-2 Years Prenatally Exposed to Plasmodium falciparum: Tanzanian Birth Cohort. J Trop Med 2018; 2018:6847498. [PMID: 30154871 PMCID: PMC6091450 DOI: 10.1155/2018/6847498] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 06/21/2018] [Accepted: 07/11/2018] [Indexed: 12/17/2022] Open
Abstract
Background Infants born to mothers with placental malaria are prenatally exposed to Plasmodium falciparum antigens. However, the effect of that exposure to subsequent immune responses has not been fully elucidated. This study aimed at determining the effect of prenatal exposure to P. falciparum on Interleukin-10 and Interferon-γ responses during clinical malaria episodes in the first 24 months of life. Methods This prospective cohort study involved 215 infants aged 0-2 years born to mothers with or without placental malaria. Enzyme-linked immunosorbent assay (ELISA) was used to determine levels of IL-10 and IFN-γ in infants and detect IgM in cord blood. Data were analyzed using SPSS version 20. Findings Geometric mean for IFN-γ in exposed infants was 557.9 pg/ml (95% CI: 511.6-604.1) and in unexposed infants it was 634.4 pg/ml (95% CI: 618.2-668.5) (P=0.02). Mean IL-10 was 22.4 pg/ml (95% CI: 19.4-28.4) and 15.1 pg/ml (95%CI: 12.4-17.6), respectively (P=0.01). Conclusions Prenatal exposure to P. falciparum antigens significantly affects IL-10 and IFN-γ responses during clinical malaria episodes in the first two years of life.
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Good MF, Miller LH. Interpreting challenge data from early phase malaria blood stage vaccine trials. Expert Rev Vaccines 2018; 17:189-196. [PMID: 29382292 DOI: 10.1080/14760584.2018.1435278] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION As the quest for an effective blood stage malaria vaccine continues, there is increasing reliance on the use of controlled human malaria infections (CHMI) in non-endemic settings to test vaccine efficacy at the earliest possible time. This is seen as a way to accelerate vaccine research and quickly eliminate candidates with poor efficacy. Areas covered: The data from these studies need to be carefully examined and interpreted in light of the very different roles that antibody and cellular immunity play in protection and within the context of the distinct clinical sensitivities of volunteers living in malaria-non-endemic countries compared to those living in endemic countries. With current strategies, it is likely that vaccines with protective immunological 'signatures' will be missed and potentially good candidates discarded. Expert commentary: Efficacy data from early phase vaccine trials in non-endemic countries should not be used to decide whether or not to proceed to vaccine trials in endemic countries.
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Affiliation(s)
- Michael F Good
- a Institute for Glycomics , Griffith University , Queensland , Australia.,b Department of Medical Microbiology and Immunology, University of Alberta , Edmonton , Canada
| | - Louis H Miller
- c Malaria Cell Biology Section, National Institute of Allergy and Infectious Diseases , National Institutes of Health , Bethesda , MD , USA
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10
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Weber GE, White MT, Babakhanyan A, Sumba PO, Vulule J, Ely D, John C, Angov E, Lanar D, Dutta S, Narum DL, Horii T, Cowman A, Beeson J, Smith J, Kazura JW, Dent AE. Sero-catalytic and Antibody Acquisition Models to Estimate Differing Malaria Transmission Intensities in Western Kenya. Sci Rep 2017; 7:16821. [PMID: 29203846 PMCID: PMC5715086 DOI: 10.1038/s41598-017-17084-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 11/21/2017] [Indexed: 12/19/2022] Open
Abstract
We sought to identify a subset of Plasmodium falciparum antibody targets that would inform monitoring efforts needed to eliminate malaria in high transmission settings. IgG antibodies to 28 recombinant Pf antigens were measured in residents of two communities in western Kenya examined in 2003 and 2013, when the respective prevalence of asymptomatic parasitemia among children was 81 and 15 percent by microscopy. Annual seroconversion rates based on a sero-catalytic model that dichotomised antibody values to negative versus positive showed that rates were higher in 2003 than 2013 for 1 pre-erythrocytic and 7 blood-stage antigens. Antibody acquisition models that considered antibody levels as continuous variables showed that age-related antibody levels to Circumsporozoite Protein and 10 merozoite proteins increased at different rates with age in 2003 versus 2013. Both models found that antibodies to 5 proteins of the Merozoite Surface Protein 1 complex were differentially acquired between the cohorts, and that changes in antibody levels to Apical Membrane Antigen 1 suggested a decrease in transmission that occurred ~10 years before 2013. Further studies evaluating antibodies to this subset of Pf antigens as biomarkers of malaria exposure and naturally acquired immunity are warranted in endemic settings where transmission has been reduced but persists.
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Affiliation(s)
- Grace E Weber
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | | | - Anna Babakhanyan
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA
| | | | - John Vulule
- Kenya Medical Research Institute, Kisumu, Kenya
| | - Dylan Ely
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA
| | - Chandy John
- Department of Pediatrics, Riley Hospital, Indiana University, Indianapolis, IN, USA
| | - Evelina Angov
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - David Lanar
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Sheetij Dutta
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - David L Narum
- Laboratory of Malaria Immunology and Vaccinology, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Toshihiro Horii
- Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Alan Cowman
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | | | - Joseph Smith
- Center for Infectious Disease Research, Seattle, WA, USA
| | - James W Kazura
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA.
| | - Arlene E Dent
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA.,Department of Pediatrics, Rainbow Babies and Children's Hospital, Cleveland, OH, USA
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11
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Ayieko C, Ogola BS, Ochola L, Ngwena GAM, Ayodo G, Hodges JS, Noland GS, John CC. Interferon- γ responses to Plasmodium falciparum vaccine candidate antigens decrease in the absence of malaria transmission. PeerJ 2017; 5:e2855. [PMID: 28097063 PMCID: PMC5228499 DOI: 10.7717/peerj.2855] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 12/02/2016] [Indexed: 01/29/2023] Open
Abstract
Background Malaria elimination campaigns are planned or active in many countries. The effects of malaria elimination on immune responses such as antigen-specific IFN- γ responses are not well characterized. Methods IFN- γ responses to the P. falciparum antigens circumsporozoite protein, liver stage antigen-1, thrombospondin-related adhesive protein, apical membrane antigen-1, MB2, and merozoite surface protein-1 were tested by ELISA in 243 individuals in highland Kenya in April 2008, October 2008, and April 2009, after a one-year period of interrupted malaria transmission from April 2007 to March 2008. Results While one individual (0.4%) tested positive for P. falciparum by PCR inOctober 2008 and another two (0.9%) tested positive in April 2009, no clinical malaria cases were detected during weekly visits. Levels of IFN-γ to all antigens decreased significantly from April 2008 to April 2009 (all P < 0.001). Discussion Naturally acquired IFN- γ responses to P. falciparum antigensare short-lived in the absence of repeated P. falciparum infection. Even short periods of malaria interruption may significantly decrease IFN-γ responses to P. falciparum antigens.
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Affiliation(s)
- Cyrus Ayieko
- Department of Zoology, Maseno University, Maseno, Kenya
| | - Bilha S Ogola
- Department of Biological Sciences, Masai Mara University, Narok, Kenya
| | - Lyticia Ochola
- Department Biological Sciences, Kabianga University, Kericho, Kenya
| | | | - George Ayodo
- School of Health Sciences, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya
| | - James S Hodges
- School of Public Health, University of Minnesota, Minneapolis, MN, United States
| | - Gregory S Noland
- Medical School, University of Minnesota, Minneapolis, MN, United States
| | - Chandy C John
- Medical School, Indiana University, Indianapolis, IN, United States
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12
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Bowman NM, Juliano JJ, Snider CJ, Kharabora O, Meshnick SR, Vulule J, John CC, Moormann AM. Longevity of Genotype-Specific Immune Responses to Plasmodium falciparum Merozoite Surface Protein 1 in Kenyan Children from Regions of Different Malaria Transmission Intensity. Am J Trop Med Hyg 2016; 95:580-7. [PMID: 27481054 DOI: 10.4269/ajtmh.15-0710] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 06/02/2016] [Indexed: 01/06/2023] Open
Abstract
Naturally acquired immunity to Plasmodium falciparum presents a changing landscape as malaria control programs and vaccine initiatives are implemented. Determining which immunologic indicators remain surrogates of past infection, as opposed to mediators of protection, led us to compare stability of immune responses across regions with divergent malaria transmission intensities. A repeat cross-sectional study of Kenyan children from a malaria-holoendemic area and an epidemic-prone area was used to examine longitudinal antibody and interferon-gamma (IFN-γ) responses to the 3D7 and FVO variants of merozoite surface protein 1 (MSP1). Antibodies to MSP1 were common in both study populations and did not significantly wane over a 21-month time period. IFN-γ responses were less frequent and rapidly disappeared in children after a prolonged period of no malaria transmission. Antibody and IFN-γ responses rarely correlated with each other; however, MSP1-specific IFN-γ response correlated with lack of concurrent P. falciparum parasitemia of the same genotype, though only statistically significantly in the malaria-holoendemic region (odds ratio = 0.31, 95% confidence interval = 0.12-0.84). This study affirms that antimalarial antibodies are informative for evaluation of history of malaria exposure within individuals, whereas cell-mediated immunity, though short lived under natural exposure conditions, might provide an assessment of recent infection and protection from parasitemia.
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Affiliation(s)
- Natalie M Bowman
- Division of Infectious Diseases, University of North Carolina, School of Medicine, Chapel Hill, North Carolina
| | - Jonathan J Juliano
- Division of Infectious Diseases, University of North Carolina, School of Medicine, Chapel Hill, North Carolina. Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina.
| | - Cynthia J Snider
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Oksana Kharabora
- Division of Infectious Diseases, University of North Carolina, School of Medicine, Chapel Hill, North Carolina
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - John Vulule
- Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Chandy C John
- Ryan White Center for Pediatric Infectious Disease and Global Health, Indiana University, Indianapolis, Indiana
| | - Ann M Moormann
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts
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13
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Graves SF, Kouriba B, Diarra I, Daou M, Niangaly A, Coulibaly D, Keita Y, Laurens MB, Berry AA, Vekemans J, Ripley Ballou W, Lanar DE, Dutta S, Gray Heppner D, Soisson L, Diggs CL, Thera MA, Doumbo OK, Plowe CV, Sztein MB, Lyke KE. Strain-specific Plasmodium falciparum multifunctional CD4+ T cell cytokine expression in Malian children immunized with the FMP2.1/AS02A vaccine candidate. Vaccine 2016; 34:2546-55. [DOI: 10.1016/j.vaccine.2016.04.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2015] [Revised: 03/24/2016] [Accepted: 04/07/2016] [Indexed: 12/17/2022]
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14
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Profoundly Reduced CD1c+ Myeloid Dendritic Cell HLA-DR and CD86 Expression and Increased Tumor Necrosis Factor Production in Experimental Human Blood-Stage Malaria Infection. Infect Immun 2016; 84:1403-1412. [PMID: 26902728 DOI: 10.1128/iai.01522-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/13/2016] [Indexed: 12/13/2022] Open
Abstract
Dendritic cells (DCs) are sentinels of the immune system that uniquely prime naive cells and initiate adaptive immune responses. CD1c (BDCA-1) myeloid DCs (CD1c(+) mDCs) highly express HLA-DR, have a broad Toll-like receptor (TLR) repertoire, and secrete immune modulatory cytokines. To better understand immune responses to malaria, CD1c(+) mDC maturation and cytokine production were examined in healthy volunteers before and after experimental intravenous Plasmodium falciparum infection with 150- or 1,800-parasite-infected red blood cells (pRBCs). After either dose, CD1c(+) mDCs significantly reduced HLA-DR expression in prepatent infections. Circulating CD1c(+) mDCs did not upregulate HLA-DR after pRBC or TLR ligand stimulation and exhibited reduced CD86 expression. At peak parasitemia, CD1c(+) mDCs produced significantly more tumor necrosis factor (TNF), whereas interleukin-12 (IL-12) production was unchanged. Interestingly, only the 1,800-pRBC dose caused a reduction in the circulating CD1c(+) mDC count with evidence of apoptosis. The 1,800-pRBC dose produced no change in T cell IFN-γ or IL-2 production at peak parasitemia or at 3 weeks posttreatment. Overall, CD1c(+) mDCs are compromised by P. falciparum exposure, with impaired HLA-DR and CD86 expression, and have an increased capacity for TNF but not IL-12 production. A first prepatent P. falciparum infection is sufficient to modulate CD1c(+) mDC responsiveness, likely contributing to hampered effector T cell cytokine responses and assisting parasite immune evasion.
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15
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Ord RL, Rodriguez M, Lobo CA. Malaria invasion ligand RH5 and its prime candidacy in blood-stage malaria vaccine design. Hum Vaccin Immunother 2016; 11:1465-73. [PMID: 25844685 DOI: 10.1080/21645515.2015.1026496] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
With drug resistance to available therapeutics continuing to develop against Plasmodium falciparum malaria, the development of an effective vaccine candidate remains a major research goal. Successful interruption of invasion of parasites into erythrocytes during the blood stage of infection will prevent the severe clinical symptoms and complications associated with malaria. Previously studied blood stage antigens have highlighted the hurdles that are inherent to this life-cycle stage, namely that highly immunogenic antigens are also globally diverse, resulting in protection only against the vaccine strain, or that naturally acquired immunity to blood stage antigens do not always correlate with actual protection. The blood stage antigen reticulocyte binding homolog RH5 is essential for parasite viability, has globally limited diversity, and is associated with protection from disease. Here we summarize available information on this invasion ligand and recent findings that highlight its candidacy for inclusion in a blood-stage malaria vaccine.
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Affiliation(s)
- Rosalynn L Ord
- a Blood-Borne Parasites; Lindsley Kimball Research Institute; New York Blood Center ; New York , NY , USA
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16
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Mendonça VRD, Barral-Netto M. Immunoregulation in human malaria: the challenge of understanding asymptomatic infection. Mem Inst Oswaldo Cruz 2015; 110:945-55. [PMID: 26676319 PMCID: PMC4708013 DOI: 10.1590/0074-02760150241] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/23/2015] [Indexed: 12/21/2022] Open
Abstract
Asymptomatic Plasmodium infection carriers represent a major threat
to malaria control worldwide as they are silent natural reservoirs and do not seek
medical care. There are no standard criteria for
asymptomaticPlasmodium infection; therefore, its diagnosis relies
on the presence of the parasite during a specific period of symptomless infection.
The antiparasitic immune response can result in reducedPlasmodium
sp. load with control of disease manifestations, which leads to asymptomatic
infection. Both the innate and adaptive immune responses seem to play major roles in
asymptomatic Plasmodiuminfection; T regulatory cell activity
(through the production of interleukin-10 and transforming growth factor-β) and
B-cells (with a broad antibody response) both play prominent roles. Furthermore,
molecules involved in the haem detoxification pathway (such as haptoglobin and haeme
oxygenase-1) and iron metabolism (ferritin and activated c-Jun N-terminal kinase)
have emerged in recent years as potential biomarkers and thus are helping to unravel
the immune response underlying asymptomatic Plasmodium infection.
The acquisition of large data sets and the use of robust statistical tools, including
network analysis, associated with well-designed malaria studies will likely help
elucidate the immune mechanisms responsible for asymptomatic infection.
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Affiliation(s)
- Vitor R de Mendonça
- Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, BA, Brasil
| | - Manoel Barral-Netto
- Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, BA, Brasil
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17
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Walker KM, Okitsu S, Porter DW, Duncan C, Amacker M, Pluschke G, Cavanagh DR, Hill AVS, Todryk SM. Antibody and T-cell responses associated with experimental human malaria infection or vaccination show limited relationships. Immunology 2015; 145:71-81. [PMID: 25471322 DOI: 10.1111/imm.12428] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 11/17/2014] [Accepted: 11/21/2014] [Indexed: 02/02/2023] Open
Abstract
This study examined specific antibody and T-cell responses associated with experimental malaria infection or malaria vaccination, in malaria-naive human volunteers within phase I/IIa vaccine trials, with a view to investigating inter-relationships between these types of response. Malaria infection was via five bites of Plasmodium falciparum-infected mosquitoes, with individuals reaching patent infection by 11-12 days, having harboured four or five blood-stage cycles before drug clearance. Infection elicited a robust antibody response against merozoite surface protein-119 , correlating with parasite load. Classical class switching was seen from an early IgM to an IgG1-dominant response of increasing affinity. Malaria-specific T-cell responses were detected in the form of interferon-γ and interleukin-4 (IL-4) ELIspot, but their magnitude did not correlate with the magnitude of antibody or its avidity, or with parasite load. Different individuals who were immunized with a virosome vaccine comprising influenza antigens combined with P. falciparum antigens, demonstrated pre-existing interferon-γ, IL-2 and IL-5 ELIspot responses against the influenza antigens, and showed boosting of anti-influenza T-cell responses only for IL-5. The large IgG1-dominated anti-parasite responses showed limited correlation with T-cell responses for magnitude or avidity, both parameters being only negatively correlated for IL-5 secretion versus anti-apical membrane antigen-1 antibody titres. Overall, these findings suggest that cognate T-cell responses across a range of magnitudes contribute towards driving potentially effective antibody responses in infection-induced and vaccine-induced immunity against malaria, and their existence during immunization is beneficial, but magnitudes are mostly not inter-related.
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Affiliation(s)
- Karen M Walker
- Department of Applied Sciences, Faculty of Health & Life Sciences, Northumbria University, Newcastle-upon-Tyne, UK
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18
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Preserved dendritic cell HLA-DR expression and reduced regulatory T cell activation in asymptomatic Plasmodium falciparum and P. vivax infection. Infect Immun 2015; 83:3224-32. [PMID: 26034211 DOI: 10.1128/iai.00226-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 05/24/2015] [Indexed: 02/04/2023] Open
Abstract
Clinical illness with Plasmodium falciparum or Plasmodium vivax compromises the function of dendritic cells (DC) and expands regulatory T (Treg) cells. Individuals with asymptomatic parasitemia have clinical immunity, restricting parasite expansion and preventing clinical disease. The role of DC and Treg cells during asymptomatic Plasmodium infection is unclear. During a cross-sectional household survey in Papua, Indonesia, we examined the number and activation of blood plasmacytoid DC (pDC), CD141(+), and CD1c(+) myeloid DC (mDC) subsets and Treg cells using flow cytometry in 168 afebrile children (of whom 15 had P. falciparum and 36 had P. vivax infections) and 162 afebrile adults (of whom 20 had P. falciparum and 20 had P. vivax infections), alongside samples from 16 patients hospitalized with uncomplicated malaria. Unlike DC from malaria patients, DC from children and adults with asymptomatic, microscopy-positive P. vivax or P. falciparum infection increased or retained HLA-DR expression. Treg cells in asymptomatic adults and children exhibited reduced activation, suggesting increased immune responsiveness. The pDC and mDC subsets varied according to clinical immunity (asymptomatic or symptomatic Plasmodium infection) and, in asymptomatic infection, according to host age and parasite species. In conclusion, active control of asymptomatic infection was associated with and likely contingent upon functional DC and reduced Treg cell activation.
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19
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Dent AE, Nakajima R, Liang L, Baum E, Moormann AM, Sumba PO, Vulule J, Babineau D, Randall A, Davies DH, Felgner PL, Kazura JW. Plasmodium falciparum Protein Microarray Antibody Profiles Correlate With Protection From Symptomatic Malaria in Kenya. J Infect Dis 2015; 212:1429-38. [PMID: 25883384 DOI: 10.1093/infdis/jiv224] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/25/2015] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Immunoglobulin G antibodies (Abs) to Plasmodium falciparum antigens have been associated with naturally acquired immunity to symptomatic malaria. METHODS We probed protein microarrays covering 824 unique P. falciparum protein features with plasma from residents of a community in Kenya monitored for 12 weeks for (re)infection and symptomatic malaria after administration of antimalarial drugs. P. falciparum proteins recognized by Abs from 88 children (aged 1-14 years) and 86 adults (aged ≥ 18 years), measured at the beginning of the observation period, were ranked by Ab signal intensity. RESULTS Abs from immune adults reacted with a total 163 of 824 P. falciparum proteins. Children gradually acquired Abs to the full repertoire of antigens recognized by adults. Abs to some antigens showed high seroconversion rates, reaching maximal levels early in childhood, whereas others did not reach adult levels until adolescence. No correlation between Ab signal intensity and time to (re)infection was observed. In contrast, Ab levels to 106 antigens were significantly higher in children who were protected from symptomatic malaria compared with those who were not. Abs to antigens predictive of protection included P. falciparum erythrocyte membrane protein 1, merozoite surface protein (MSP) 10, MSP2, liver-stage antigen 3, PF70, MSP7, and Plasmodium helical interspersed subtelomeric domain protein. CONCLUSIONS Protein microarrays may be useful in the search for malaria antigens associated with protective immunity.
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Affiliation(s)
- Arlene E Dent
- Center for Global Health and Diseases, Case Western Reserve University Rainbow Babies and Children's Hospital, Cleveland, Ohio
| | | | - Li Liang
- University of California, Irvine
| | | | - Ann M Moormann
- Center for Global Health Research, University of Massachusetts Medical School, Worcester
| | | | | | | | | | | | | | - James W Kazura
- Center for Global Health and Diseases, Case Western Reserve University
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20
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Boyle MJ, Jagannathan P, Bowen K, McIntyre TI, Vance HM, Farrington LA, Greenhouse B, Nankya F, Rek J, Katureebe A, Arinaitwe E, Dorsey G, Kamya MR, Feeney ME. Effector Phenotype of Plasmodium falciparum-Specific CD4+ T Cells Is Influenced by Both Age and Transmission Intensity in Naturally Exposed Populations. J Infect Dis 2015; 212:416-25. [PMID: 25646355 DOI: 10.1093/infdis/jiv054] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 01/20/2015] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Mechanisms mediating immunity to malaria remain unclear, but animal data and experimental human vaccination models suggest a critical role for CD4(+) T cells. Advances in multiparametric flow cytometry have revealed that the functional quality of pathogen-specific CD4(+) T cells determines immune protection in many infectious models. Little is known about the functional characteristics of Plasmodium-specific CD4(+) T-cell responses in immune and nonimmune individuals. METHODS We compared T-cell responses to Plasmodium falciparum among household-matched children and adults residing in settings of high or low malaria transmission in Uganda. Peripheral blood mononuclear cells were stimulated with P. falciparum antigen, and interferon γ (IFN-γ), interleukin 2, interleukin 10, and tumor necrosis factor α (TNF-α) production was analyzed via multiparametric flow cytometry. RESULTS We found that the magnitude of the CD4(+) T-cell responses was greater in areas of high transmission but similar between children and adults in each setting type. In the high-transmission setting, most P. falciparum-specific CD4(+) T-cells in children produced interleukin 10, while responses in adults were dominated by IFN-γ and TNF-α. In contrast, in the low-transmission setting, responses in both children and adults were dominated by IFN-γ and TNF-α. CONCLUSIONS These findings highlight major differences in the CD4(+) T-cell response of immune adults and nonimmune children that may be relevant for immune protection from malaria.
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Affiliation(s)
- Michelle J Boyle
- Department of Medicine Center for Biomedical Research, Burnet Institute, Melbourne, Australia
| | | | | | | | | | | | | | | | - John Rek
- Infectious Diseases Research Collaboration
| | | | | | | | - Moses R Kamya
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Margaret E Feeney
- Department of Medicine Department of Pediatrics, University of California-San Francisco
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21
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Pinkevych M, Chelimo K, Vulule J, Kazura JW, Moormann AM, Davenport MP. Time-to-infection by Plasmodium falciparum is largely determined by random factors. BMC Med 2015; 13:19. [PMID: 25633459 PMCID: PMC4311447 DOI: 10.1186/s12916-014-0252-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 12/10/2014] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The identification of protective immune responses to P. falciparum infection is an important goal for the development of a vaccine for malaria. This requires the identification of susceptible and resistant individuals, so that their immune responses may be studied. Time-to-infection studies are one method for identifying putative susceptible individuals (infected early) versus resistant individuals (infected late). However, the timing of infection is dependent on random factors, such as whether the subject was bitten by an infected mosquito, as well as individual factors, such as their level of immunity. It is important to understand how much of the observed variation in infection is simply due to chance. METHODS We analyse previously published data from a treatment-time-to-infection study of 201 individuals aged 0.5 to 78 years living in Western Kenya. We use a mathematical modelling approach to investigate the role of immunity versus random factors in determining time-to-infection in this cohort. We extend this analysis using a modelling approach to understand what factors might increase or decrease the utility of these studies for identifying susceptible and resistant individuals. RESULTS We find that, under most circumstances, the observed distribution of time-to-infection is consistent with this simply being a random process. We find that age, method for detection of infection (PCR versus microscopy), and underlying force of infection are all factors in determining whether time-to-infection is a useful correlate of immunity. CONCLUSIONS Many epidemiological studies of P. falciparum infection assume that the observed variation in infection outcomes, such as time-to-infection or presence or absence of infection, is determined by host resistance or susceptibility. However, under most circumstances, this distribution appears largely due to the random timing of infection, particularly in children. More direct measurements, such as parasite growth rate, may be more useful than time-to-infection in segregating patients based on their level of immunity.
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Affiliation(s)
| | | | | | | | | | - Miles P Davenport
- Centre for Vascular Research, University of New South Wales Australia, Kensington NSW 2052, Sydney, Australia.
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22
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Innate immunity induced by Plasmodium liver infection inhibits malaria reinfections. Infect Immun 2015; 83:1172-80. [PMID: 25583524 DOI: 10.1128/iai.02796-14] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Following transmission through a mosquito bite to the mammalian host, Plasmodium parasites first invade and replicate inside hepatocytes before infecting erythrocytes and causing malaria. The mechanisms limiting Plasmodium reinfections in humans living in regions of malaria endemicity have mainly been explored by studying the resistance induced by the blood stage of infection. However, epidemiologic studies have suggested that in high-transmission areas, preerythrocytic stages also activate host resistance to reinfection. This, along with the recent discovery that liver infections trigger a specific and effective type I interferon (IFN) response, prompted us to hypothesize that this pre-erythrocyte-stage-induced resistance is linked to liver innate immunity. Here, we combined experimental approaches and mathematical modeling to recapitulate field studies and understand the molecular basis behind such resistance. We present a newly established mouse reinfection model and demonstrate that rodent malaria liver-stage infection inhibits reinfection. This protection relies on the activation of innate immunity and involves the type I IFN response and the antimicrobial cytokine gamma IFN (IFN-γ). Importantly, mathematical simulations indicate that the predictions based on our experimental murine reinfection model fit available epidemiological data. Overall, our study revealed that liver-stage-induced innate immunity may contribute to the preerythrocytic resistance observed in humans in regions of malaria hyperendemicity.
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23
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Jagannathan P, Nankya F, Stoyanov C, Eccles-James I, Sikyomu E, Naluwu K, Wamala S, Nalubega M, Briggs J, Bowen K, Bigira V, Kapisi J, Kamya MR, Dorsey G, Feeney ME. IFNγ Responses to Pre-erythrocytic and Blood-stage Malaria Antigens Exhibit Differential Associations With Past Exposure and Subsequent Protection. J Infect Dis 2014; 211:1987-96. [PMID: 25520427 DOI: 10.1093/infdis/jiu814] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 12/10/2014] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The malaria-specific T-cell response is believed to be important for protective immunity. Antimalarial chemoprevention may affect this response by altering exposure to malaria antigens. METHODS We performed interferon γ (IFNγ) ELISpot assays to assess the cellular immune response to blood-stage and pre-erythrocytic antigens longitudinally from 1 to 3 years of age in 196 children enrolled in a randomized trial of antimalarial chemoprevention in Tororo, Uganda, an area of high transmission intensity. RESULTS IFNγ responses to blood-stage antigens, particularly MSP1, were frequently detected, strongly associated with recent malaria exposure, and lower in those adherent to chemoprevention compared to nonadherent children and those randomized to no chemoprevention. IFNγ responses to pre-erythrocytic antigens were infrequent and similar between children randomized to chemoprevention or no chemoprevention. Responses to blood-stage antigens were not associated with subsequent protection from malaria (aHR 0.96, P = .83), but responses to pre-erythrocytic antigens were associated with protection after adjusting for prior malaria exposure (aHR 0.52, P = .009). CONCLUSIONS In this high transmission setting, IFNγ responses to blood-stage antigens were common and associated with recent exposure to malaria but not protection from subsequent malaria. Responses to pre-erythrocytic antigens were uncommon, not associated with exposure but were associated with protection from subsequent malaria.
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Affiliation(s)
- Prasanna Jagannathan
- Department of Medicine, San Francisco General Hospital, University of California
| | | | - Cristina Stoyanov
- Department of Medicine, San Francisco General Hospital, University of California
| | - Ijeoma Eccles-James
- Department of Medicine, San Francisco General Hospital, University of California
| | | | | | | | | | - Jessica Briggs
- Department of Medicine, San Francisco General Hospital, University of California
| | - Katherine Bowen
- Department of Medicine, San Francisco General Hospital, University of California
| | | | | | - Moses R Kamya
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Grant Dorsey
- Department of Medicine, San Francisco General Hospital, University of California
| | - Margaret E Feeney
- Department of Medicine, San Francisco General Hospital, University of California Department of Pediatrics, University of California, San Francisco
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24
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Garrod TJ, Gargett T, Yu W, Major L, Burrell CJ, Wesselingh S, Suhrbier A, Grubor-Bauk B, Gowans EJ. Loss of long term protection with the inclusion of HIV pol to a DNA vaccine encoding gag. Virus Res 2014; 192:25-33. [PMID: 25152448 DOI: 10.1016/j.virusres.2014.08.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 08/11/2014] [Accepted: 08/14/2014] [Indexed: 11/29/2022]
Abstract
Traditional vaccine strategies that induce antibody responses have failed to protect against HIV infection in clinical trials, and thus cell-mediated immunity is now an additional criterion. Recent clinical trials that aimed to induce strong T cell responses failed to do so. Therefore, to enhance induction of protective T cell responses, it is crucial that the optimum antigen combination is chosen. Limited research has been performed into the number of antigens selected for an HIV vaccine. This study aimed to compare DNA vaccines encoding either a single HIV antigen or a combination of two antigens, using intradermal vaccination of C57BL/6 mice. Immune assays were performed on splenocytes, and in vivo protection was examined by challenge with a chimeric virus, EcoHIV, able to infect mouse but not human leukocytes, at 10 days (short term) and 60 days (long term) post final vaccination. At 60 days there was significantly lower frequency of induced antigen-specific CD8(+) T cells in the spleens of pCMVgag-pol-vaccinated mice compared with mice which received pCMVgag only. Most importantly, short term viral control of EcoHIV was similar for pCMVgag and pCMVgag-pol-vaccinated mice at day 10, but only the pCMVgag-vaccinated significantly controlled EcoHIV at day 60 compared with pCMV-vaccinated mice, showing that control was reduced with the inclusion of the HIV pol gene.
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Affiliation(s)
- Tamsin J Garrod
- Virology Laboratory, Basil Hetzel Institute, Department of Surgery, University of Adelaide, Adelaide, Australia.
| | - Tessa Gargett
- Virology Laboratory, Basil Hetzel Institute, Department of Surgery, University of Adelaide, Adelaide, Australia
| | - Wenbo Yu
- Virology Laboratory, Basil Hetzel Institute, Department of Surgery, University of Adelaide, Adelaide, Australia
| | - Lee Major
- Inflammation Biology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | | | - Steven Wesselingh
- South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Andreas Suhrbier
- Inflammation Biology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Branka Grubor-Bauk
- Virology Laboratory, Basil Hetzel Institute, Department of Surgery, University of Adelaide, Adelaide, Australia
| | - Eric J Gowans
- Virology Laboratory, Basil Hetzel Institute, Department of Surgery, University of Adelaide, Adelaide, Australia
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25
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Jagannathan P, Eccles-James I, Bowen K, Nankya F, Auma A, Wamala S, Ebusu C, Muhindo MK, Arinaitwe E, Briggs J, Greenhouse B, Tappero JW, Kamya MR, Dorsey G, Feeney ME. IFNγ/IL-10 co-producing cells dominate the CD4 response to malaria in highly exposed children. PLoS Pathog 2014; 10:e1003864. [PMID: 24415936 PMCID: PMC3887092 DOI: 10.1371/journal.ppat.1003864] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 11/19/2013] [Indexed: 01/08/2023] Open
Abstract
Although evidence suggests that T cells are critical for immunity to malaria, reliable T cell correlates of exposure to and protection from malaria among children living in endemic areas are lacking. We used multiparameter flow cytometry to perform a detailed functional characterization of malaria-specific T cells in 78 four-year-old children enrolled in a longitudinal cohort study in Tororo, Uganda, a highly malaria-endemic region. More than 1800 episodes of malaria were observed in this cohort, with no cases of severe malaria. We quantified production of IFNγ, TNFα, and IL-10 (alone or in combination) by malaria-specific T cells, and analyzed the relationship of this response to past and future malaria incidence. CD4+ T cell responses were measurable in nearly all children, with the majority of children having CD4+ T cells producing both IFNγ and IL-10 in response to malaria-infected red blood cells. Frequencies of IFNγ/IL10 co-producing CD4+ T cells, which express the Th1 transcription factor T-bet, were significantly higher in children with ≥2 prior episodes/year compared to children with <2 episodes/year (P<0.001) and inversely correlated with duration since malaria (Rho = −0.39, P<0.001). Notably, frequencies of IFNγ/IL10 co-producing cells were not associated with protection from future malaria after controlling for prior malaria incidence. In contrast, children with <2 prior episodes/year were significantly more likely to exhibit antigen-specific production of TNFα without IL-10 (P = 0.003). While TNFα-producing CD4+ T cells were not independently associated with future protection, the absence of cells producing this inflammatory cytokine was associated with the phenotype of asymptomatic infection. Together these data indicate that the functional phenotype of the malaria-specific T cell response is heavily influenced by malaria exposure intensity, with IFNγ/IL10 co-producing CD4+ T cells dominating this response among highly exposed children. These CD4+ T cells may play important modulatory roles in the development of antimalarial immunity. Despite reports of decreasing malaria morbidity across many parts of Africa, the incidence of malaria among children continues to be very high in Uganda, even in the setting of insecticide-treated bednets and artemisinin-based combination therapy. Additional control measures, including a vaccine, are sorely needed in these settings, but progress has been limited by our lack of understanding of immunologic correlates of exposure and protection. T cell responses to malaria are thought to be important for protection in experimental models, but their role in protecting against naturally acquired infection is not clear. In this study, we performed detailed assessments of the malaria-specific T cell response among 4-year-old children living in Tororo, Uganda, an area of high malaria transmission. We found that recent malaria infection induces a malaria-specific immune response dominated by Th1 T cells co-producing IFNγ and IL-10, and that these cells are not associated with protection from future infection. IFNγ/IL-10 co-producing cells have been described in several parasitic infections and are hypothesized to be important in limiting CD4-mediated pathology, but they may also prevent the development of sterilizing immunity. These observations have important implications for understanding the pathophysiology of malaria in humans and for malaria vaccine development.
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Affiliation(s)
- Prasanna Jagannathan
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, San Francisco, California, United States of America
| | - Ijeoma Eccles-James
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, San Francisco, California, United States of America
| | - Katherine Bowen
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, San Francisco, California, United States of America
| | | | - Ann Auma
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Samuel Wamala
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Charles Ebusu
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | | | - Jessica Briggs
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, San Francisco, California, United States of America
| | - Bryan Greenhouse
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, San Francisco, California, United States of America
| | - Jordan W. Tappero
- Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Moses R. Kamya
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Grant Dorsey
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, San Francisco, California, United States of America
| | - Margaret E. Feeney
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, San Francisco, California, United States of America
- Department of Pediatrics, University of California, San Francisco, San Francisco, California, United States of America
- * E-mail:
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Pinkevych M, Petravic J, Chelimo K, Vulule J, Kazura JW, Moormann AM, Davenport MP. Decreased growth rate of P. falciparum blood stage parasitemia with age in a holoendemic population. J Infect Dis 2013; 209:1136-43. [PMID: 24265441 DOI: 10.1093/infdis/jit613] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In malaria holoendemic settings, decreased parasitemia and clinical disease is associated with age and cumulative exposure. The relative contribution of acquired immunity against various stages of the parasite life cycle is not well understood. In particular, it is not known whether changes in infection dynamics can be best explained by decreasing rates of infection, or by decreased growth rates of parasites in blood. Here, we analyze the dynamics of Plasmodium falciparum infection after treatment in a cohort of 197 healthy study participants of different ages. We use both polymerase chain reaction (PCR) and microscopy detection of parasitemia in order to understand parasite growth rates and infection rates over time. The more sensitive PCR assay detects parasites earlier than microscopy, and demonstrates a higher overall prevalence of infection than microscopy alone. The delay between PCR and microscopy detection is significantly longer in adults compared with children, consistent with slower parasite growth with age. We estimated the parasite multiplication rate from delay to PCR and microscopy detections of parasitemia. We find that both the delay between PCR and microscopy infection as well as the differing reinfection dynamics in different age groups are best explained by a slowing of parasite growth with age.
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Affiliation(s)
- Mykola Pinkevych
- Centre for Vascular Research, University of New South Wales, Sydney, New South Wales, Australia
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Pinkevych M, Petravic J, Chelimo K, Vulule J, Kazura JW, Moormann AM, Davenport MP. Density-dependent blood stage Plasmodium falciparum suppresses malaria super-infection in a malaria holoendemic population. Am J Trop Med Hyg 2013; 89:850-6. [PMID: 24019439 DOI: 10.4269/ajtmh.13-0049] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Recent studies of Plasmodium berghei malaria in mice show that high blood-stage parasitemia levels inhibit the development of subsequent liver-stage infections. Whether a similar inhibitory effect on liver-stage Plasmodium falciparum by blood-stage infection occurs in humans is unknown. We have analyzed data from a treatment-time-to-infection cohort of children < 10 years of age residing in a malaria holoendemic area of Kenya where people experience a new blood-stage infection approximately every 2 weeks. We hypothesized that if high parasitemia blocked the liver stage, then high levels of parasitemia should be followed by a "skipped" peak of parasitemia. Statistical analysis of "natural infection" field data and stochastic simulation of infection dynamics show that the data are consistent with high P. falciparum parasitemia inhibiting liver-stage parasite development in humans.
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Affiliation(s)
- Mykola Pinkevych
- Centre for Vascular Research, University of New South Wales, Sydney, NSW, Australia; Kenya Medical Research Institute, Kisumu, Kenya; Case Western Reserve University, Cleveland, Ohio; University of Massachusetts Medical School, Worcester, Massachusetts
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