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Hamisi MA, Asri NAM, Yassim ASM, Suppian R. A systematic review on malaria and Tuberculosis (TB) vaccine challenges in sub-Saharan African clinical trials. PLoS One 2025; 20:e0317233. [PMID: 39854359 PMCID: PMC11760592 DOI: 10.1371/journal.pone.0317233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 12/25/2024] [Indexed: 01/26/2025] Open
Abstract
OBJECTIVE For more than a century, developing novel and effective vaccines against malaria and Tuberculosis (TB) infections has been a challenge. This review sought to investigate the reasons for the slow progress of malaria and TB vaccine candidates in sub-Saharan African clinical trials. METHODS The systematic review protocol was registered on PROSPERO on July 26, 2023 (CRD42023445166). The research articles related to the immunogenicity, efficacy, or safety of malaria or TB vaccines that were published between January 1, 2012, and August 31, 2023, were searched on three databases: Web of Science (WoS), PubMed, and ClinicalTrials.gov. RESULTS A total of 2342 articles were obtained, 50 of which met the inclusion criteria. 28 (56%) articles reported on malaria vaccine attributes, while 22 (44%) articles reported on TB vaccines. In both cases, the major challenges in sub-Saharan African clinical trials were immunogenicity and efficacy, rather than safety. CONCLUSION Factors such as population characteristics, pathogen genetic diversity, vaccine nature, strategy, and formulation were associated with slow progress of the malaria and TB vaccine candidates in sub-Saharan African clinical trials.
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Affiliation(s)
- Maonezi Abas Hamisi
- School of Science and Technical Education (CoSTE), Mbeya University of Science and Technology, Mbeya, Tanzania
| | - Nur Ain Mohd Asri
- School of Health Sciences, Universiti Sains Malaysia, Kota Bharu, Kelantan, Malaysia
| | | | - Rapeah Suppian
- School of Health Sciences, Universiti Sains Malaysia, Kota Bharu, Kelantan, Malaysia
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Asare KK, Kwapong SS, Tey P, Sackey V, Nuvor SV, Amoah LE. Plasmodium Falciparum and mosquito vector IgG patterns across suspected malaria cases in Ghana. BMC Infect Dis 2024; 24:1374. [PMID: 39623362 PMCID: PMC11613542 DOI: 10.1186/s12879-024-10248-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2024] [Accepted: 11/18/2024] [Indexed: 12/06/2024] Open
Abstract
INTRODUCTION Malaria, a widespread tropical disease, remains a significant global health issue, resulting in numerous deaths each year. In Ghana, malaria is a leading cause of illness, contributing to a large proportion of hospital outpatient visits. The study assessed the pattern of malaria and vector IgG antibody levels among suspected malaria patients seeking healthcare at selected health facilities across Ghana. METHODS Samples from a total of 823 participants aged 1 to 85 years with clinical malaria from the ten regions of Ghana were recruited into the study. Archived plasma obtained from each participant was used to assess antibody responses against MSP1 (19 k), MSP2 (FC27 & 3D7), MSP3, gSG6-P1, and GLURP-RO using ELISA. The data were categorized according to study site, age group, gender, and diagnostic tests. Data were analyzed using Kruskal-Wallis's statistics. The statistical significance was assessed at 0.05. RESULTS The mean ± standard error of the mean (S.E) of MSP3 IgG concentration for the different age groups were 16, 847 ± 3, 031 ng/mL for 0-4 years, 18, 973 ± 4,357 ng/mL for 5-10 years, 25,961 ± 5,436 ng/mL for 11-15 years and 76, 244 ± 8, 209 ng/mL for ≥ 16 years. A significant (Kruskal-Wallis statistic = 122.6, p < 0.0001) increase in P. falciparum MSP 3 (p < 0.0001) and gSG6-P1(p < 0.0001) IgG concentration was observed with increasing age categories. There were significant differences in antibody responses against MSP2 (FC27) IgG (Kruskal-Wallis statistic = 29.63, p = 0.0005), MSP3 IgG (Kruskal-Wallis statistic = 32.53, p = 0.0002), GLURP-RO IgG (Kruskal-Wallis statistic = 52.8, p < 0.0001) and gSG6-P1 IgG (Kruskal-Wallis statistic = 152.8, p < 0.0001) across the study regions. CONCLUSION The study reveals that IgG against merozoite surface proteins MSP3, GLURP-RO, and gSG6-P1 but not MSP1 and MSP2 antibodies increase with age. The mean IgG antibody concentrations varied in the selected regions of Ghana. A longitudinal study where confounding factors are controlled for is recommended to provide insights into the development of immunity and antibody efficacy, and to enhance the effectiveness of malaria prevention efforts in Ghana. This will help improve the overall understanding of malaria transmission.
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Affiliation(s)
- Kwame Kumi Asare
- Biomedical and Clinical Research Centre, College of Allied Health Sciences, University of Cape Coast, Cape Coast, Ghana
- Department of Biomedical Science, School of Allied Health Sciences, University of Cape Coast, Cape Coast, Ghana
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Sebastian Shine Kwapong
- Department of Microbiology and Immunology, School of Medical Sciences, University of Cape Coast, Cape Coast, Ghana
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Prosper Tey
- Department of Microbiology and Immunology, School of Medical Sciences, University of Cape Coast, Cape Coast, Ghana
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Vincent Sackey
- Department of Microbiology and Immunology, School of Medical Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Samuel Victor Nuvor
- Department of Microbiology and Immunology, School of Medical Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Linda Eva Amoah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.
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Frempong NA, Mama A, Adu B, Kusi KA, Ofori MF, Ahiabor C, Anyan WK, Debrah AY, Anang AA, Ndam NT, Courtin D. Antibody response to malaria vaccine candidates in pregnant women with Plasmodium falciparum and Schistosoma haematobium infections. Parasite Immunol 2024; 46:e13027. [PMID: 38587985 DOI: 10.1111/pim.13027] [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: 09/04/2023] [Revised: 12/21/2023] [Accepted: 01/22/2024] [Indexed: 04/10/2024]
Abstract
Malaria in pregnancy has severe consequences for the mother and foetus. Antibody response to specific malaria vaccine candidates (MVC) has been associated with a decreased risk of clinical malaria and its outcomes. We studied Plasmodium falciparum (Pf) and Schistosoma haematobium (Sh) infections and factors that could influence antibody responses to MVC in pregnant women. A total of 337 pregnant women receiving antenatal care (ANC) and 139 for delivery participated in this study. Pf infection was detected by qPCR and Sh infection using urine filtration method. Antibody levels against CSP, AMA-1, GLURP-R0, VAR2CSA and Pfs48/45 MVC were quantified by ELISA. Multivariable linear regression models identified factors associated with the modulation of antibody responses. The prevalence of Pf and Sh infections was 27% and 4% at ANC and 7% and 4% at delivery. Pf infection, residing in Adidome and multigravidae were positively associated with specific IgG response to CSP, AMA-1, GLURP-R0 and VAR2CSA. ITN use and IPTp were negatively associated with specific IgG response to GLURP-R0 and Pfs48/45. There was no association between Sh infection and antibody response to MVC at ANC or delivery. Pf infections in pregnant women were positively associated with antibody response to CSP, GLURP-R0 and AMA-1. Antibody response to GLURP-R0 and Pfs48/45 was low for IPTp and ITN users. This could indicate a lower exposure to Pf infection and low malaria prevalence observed at delivery.
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Affiliation(s)
- Naa Adjeley Frempong
- Department of Clinical Microbiology, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
- Parasitology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Atikatou Mama
- Inserm U 1016, Institut Cochin, Université de, Paris, France
| | - Bright Adu
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Kwadwo Asamoah Kusi
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Michael F Ofori
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Charity Ahiabor
- Science Laboratory Department, Accra Technical University, Accra, Ghana
| | - William K Anyan
- Department of Clinical Microbiology, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Alex Yaw Debrah
- Faculty of Health Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Abraham A Anang
- Institute for Environment and Sanitation Studies (IESS), University of Ghana, Legon, Ghana
| | - Nicaise T Ndam
- UMR 216 MERIT, IRD, Université Paris Cité, Paris, France
| | - David Courtin
- UMR 216 MERIT, IRD, Université Paris Cité, Paris, France
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Gao W, Qiu Y, Zhu L, Yu X, Yang F, Chen M, He G, Liu Y, Cui L, Liu F, Zhu X, Cao Y. A dual-antigen malaria vaccine targeting Pb22 and Pbg37 was able to induce robust transmission-blocking activity. Parasit Vectors 2023; 16:455. [PMID: 38098083 PMCID: PMC10720250 DOI: 10.1186/s13071-023-06071-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 11/29/2023] [Indexed: 12/18/2023] Open
Abstract
BACKGROUND Despite years of effort to develop an effective vaccine against malaria infection, a vaccine that provides individuals with sufficient protection against malaria illness and death in endemic areas is not yet available. The development of transmission-blocking vaccines (TBVs) is a promising strategy for malaria control. A dual-antigen malaria vaccine targeting both pre- and post-fertilization antigens could effectively improve the transmission-blocking activity of vaccines against the sexual stages of the parasite. METHODS A chimeric recombinant protein Pb22-Pbg37 (Plasmodium berghei 22-P. berghei G37) composed of 19-218 amino acids (aa) of Pb22 and the N-terminal 26-88 aa of Pbg37 was designed and expressed in the Escherichia coli expression system. The antibody titers of the fusion (Pb22-Pbg37) and mixed (Pb22+Pbg37) antigens, as well as those of Pb22 and Pbg37 single antigens were evaluated by enzyme-linked immunosorbent assay. Immunofluorescence and western blot assays were performed to test the reactivity of the antisera with the native proteins in the parasite. The induction of transmission-blocking activity (TBA) by Pb22-Pbg37 and Pb22+Pbg37 were evaluated by in vitro gametocyte activation, gamete and exflagellation center formation, ookinete conversion, and in the direct mosquito feeding assay. RESULTS The Pb22-Pbg37 fusion protein was successfully expressed in vitro. Co-administration of Pb22 and Pbg37 as a fusion or mixed protein elicited comparable antibody responses in mice and resulted in responses to both antigens. Most importantly, both the mixed and fusion antigens induced antibodies with significantly higher levels of TBA than did each of the individual antigens when administered alone. In addition, the efficacy of vaccination with the Pb22-Pbg37 fusion protein was equivalent to that of vaccination with the mixed single antigens. CONCLUSIONS Dual-antigen vaccines, which expand/lengthen the period during which the transmission-blocking antibodies can act during sexual-stage development, can provide a promising higher transmission-reducing activity compared to single antigens.
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Affiliation(s)
- Wenyan Gao
- Department of Immunology, College of Basic Medical Sciences, China Medical University, No.77 Puhe Road, Shenyang, 110122, Liaoning, People's Republic of China
- Department of Obstetrics, The First Affiliated Hospital of China Medical University, NO. 155, Nanjing Street, Shenyang, 110001, Liaoning, People's Republic of China
| | - Yue Qiu
- Department of Immunology, College of Basic Medical Sciences, China Medical University, No.77 Puhe Road, Shenyang, 110122, Liaoning, People's Republic of China
- Department of Cardiovascular Ultrasound, The First Hospital of China Medical University, Shenyang, 110001, Liaoning, China
| | - Liying Zhu
- Department of Immunology, College of Basic Medical Sciences, China Medical University, No.77 Puhe Road, Shenyang, 110122, Liaoning, People's Republic of China
| | - Xinxin Yu
- Department of Immunology, College of Basic Medical Sciences, China Medical University, No.77 Puhe Road, Shenyang, 110122, Liaoning, People's Republic of China
| | - Fan Yang
- Department of Immunology, College of Basic Medical Sciences, China Medical University, No.77 Puhe Road, Shenyang, 110122, Liaoning, People's Republic of China
| | - Muyan Chen
- Department of Immunology, College of Basic Medical Sciences, China Medical University, No.77 Puhe Road, Shenyang, 110122, Liaoning, People's Republic of China
| | - Gang He
- Department of Immunology, College of Basic Medical Sciences, China Medical University, No.77 Puhe Road, Shenyang, 110122, Liaoning, People's Republic of China
| | - Yinjie Liu
- Department of Immunology, College of Basic Medical Sciences, China Medical University, No.77 Puhe Road, Shenyang, 110122, Liaoning, People's Republic of China
| | - Liwang Cui
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA
| | - Fei Liu
- Department of Immunology, College of Basic Medical Sciences, China Medical University, No.77 Puhe Road, Shenyang, 110122, Liaoning, People's Republic of China.
| | - Xiaotong Zhu
- Department of Immunology, College of Basic Medical Sciences, China Medical University, No.77 Puhe Road, Shenyang, 110122, Liaoning, People's Republic of China.
| | - Yaming Cao
- Department of Immunology, College of Basic Medical Sciences, China Medical University, No.77 Puhe Road, Shenyang, 110122, Liaoning, People's Republic of China.
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B-Cell Epitope Mapping of the Plasmodium falciparum Malaria Vaccine Candidate GMZ2.6c in a Naturally Exposed Population of the Brazilian Amazon. Vaccines (Basel) 2023; 11:vaccines11020446. [PMID: 36851323 PMCID: PMC9966924 DOI: 10.3390/vaccines11020446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
The GMZ2.6c malaria vaccine candidate is a multi-stage P. falciparum chimeric protein that contains a fragment of the sexual-stage Pfs48/45-6C protein genetically fused to GMZ2, an asexual-stage vaccine construction consisting of the N-terminal region of the glutamate-rich protein (GLURP) and the C-terminal region of the merozoite surface protein-3 (MSP-3). Previous studies showed that GMZ2.6c is widely recognized by antibodies from Brazilian exposed individuals and that its components are immunogenic in natural infection by P. falciparum. In addition, anti-GMZ2.6c antibodies increase with exposure to infection and may contribute to parasite immunity. Therefore, identifying epitopes of proteins recognized by antibodies may be an important tool for understanding protective immunity. Herein, we identify and validate the B-cell epitopes of GMZ2.6c as immunogenic and immunodominant in individuals exposed to malaria living in endemic areas of the Brazilian Amazon. Specific IgG antibodies and subclasses against MSP-3, GLURP, and Pfs48/45 epitopes were detected by ELISA using synthetic peptides corresponding to B-cell epitopes previously described for MSP-3 and GLURP or identified by BepiPred for Pfs48/45. The results showed that the immunodominant epitopes were P11 from GLURP and MSP-3c and DG210 from MSP-3. The IgG1 and IgG3 subclasses were preferentially induced against these epitopes, supporting previous studies that these proteins are targets for cytophilic antibodies, important for the acquisition of protective immunity. Most individuals presented detectable IgG antibodies against Pfs48/45a and/or Pfs48/45b, validating the prediction of linear B-cell epitopes. The higher frequency and antibody levels against different epitopes from GLURP, MSP-3, and Pfs48/45 provide additional information that may suggest the relevance of GMZ2.6c as a multi-stage malaria vaccine candidate.
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Chandley P, Ranjan R, Kumar S, Rohatgi S. Host-parasite interactions during Plasmodium infection: Implications for immunotherapies. Front Immunol 2023; 13:1091961. [PMID: 36685595 PMCID: PMC9845897 DOI: 10.3389/fimmu.2022.1091961] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 12/12/2022] [Indexed: 01/05/2023] Open
Abstract
Malaria is a global infectious disease that remains a leading cause of morbidity and mortality in the developing world. Multiple environmental and host and parasite factors govern the clinical outcomes of malaria. The host immune response against the Plasmodium parasite is heterogenous and stage-specific both in the human host and mosquito vector. The Plasmodium parasite virulence is predominantly associated with its ability to evade the host's immune response. Despite the availability of drug-based therapies, Plasmodium parasites can acquire drug resistance due to high antigenic variations and allelic polymorphisms. The lack of licensed vaccines against Plasmodium infection necessitates the development of effective, safe and successful therapeutics. To design an effective vaccine, it is important to study the immune evasion strategies and stage-specific Plasmodium proteins, which are targets of the host immune response. This review provides an overview of the host immune defense mechanisms and parasite immune evasion strategies during Plasmodium infection. Furthermore, we also summarize and discuss the current progress in various anti-malarial vaccine approaches, along with antibody-based therapy involving monoclonal antibodies, and research advancements in host-directed therapy, which can together open new avenues for developing novel immunotherapies against malaria infection and transmission.
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Affiliation(s)
- Pankaj Chandley
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Roorkee, India
| | - Ravikant Ranjan
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Roorkee, India
| | - Sudhir Kumar
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Soma Rohatgi
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Roorkee, India,*Correspondence: Soma Rohatgi,
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Lyons FMT, Gabriela M, Tham WH, Dietrich MH. Plasmodium 6-Cysteine Proteins: Functional Diversity, Transmission-Blocking Antibodies and Structural Scaffolds. Front Cell Infect Microbiol 2022; 12:945924. [PMID: 35899047 PMCID: PMC9309271 DOI: 10.3389/fcimb.2022.945924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/22/2022] [Indexed: 11/30/2022] Open
Abstract
The 6-cysteine protein family is one of the most abundant surface antigens that are expressed throughout the Plasmodium falciparum life cycle. Many members of the 6-cysteine family have critical roles in parasite development across the life cycle in parasite transmission, evasion of the host immune response and host cell invasion. The common feature of the family is the 6-cysteine domain, also referred to as s48/45 domain, which is conserved across Aconoidasida. This review summarizes the current approaches for recombinant expression for 6-cysteine proteins, monoclonal antibodies against 6-cysteine proteins that block transmission and the growing collection of crystal structures that provide insights into the functional domains of this protein family.
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Affiliation(s)
- Frankie M. T. Lyons
- The Walter and Eliza Hall Institute of Medical Research, Infectious Diseases and Immune Defence Division, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Mikha Gabriela
- The Walter and Eliza Hall Institute of Medical Research, Infectious Diseases and Immune Defence Division, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Wai-Hong Tham
- The Walter and Eliza Hall Institute of Medical Research, Infectious Diseases and Immune Defence Division, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Melanie H. Dietrich
- The Walter and Eliza Hall Institute of Medical Research, Infectious Diseases and Immune Defence Division, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
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Ochwedo KO, Ariri FO, Otambo WO, Magomere EO, Debrah I, Onyango SA, Orondo PW, Atieli HE, Ogolla SO, Otieno ACA, Mukabana WR, Githeko AK, Lee MC, Yan G, Zhong D, Kazura JW. Rare Alleles and Signatures of Selection on the Immunodominant Domains of Pfs230 and Pfs48/45 in Malaria Parasites From Western Kenya. Front Genet 2022; 13:867906. [PMID: 35656326 PMCID: PMC9152164 DOI: 10.3389/fgene.2022.867906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 04/25/2022] [Indexed: 01/27/2023] Open
Abstract
Background: Malaria elimination and eradication efforts can be advanced by including transmission-blocking or reducing vaccines (TBVs) alongside existing interventions. Key transmission-blocking vaccine candidates, such as Pfs230 domain one and Pfs48/45 domain 3, should be genetically stable to avoid developing ineffective vaccines due to antigenic polymorphisms. We evaluated genetic polymorphism and temporal stability of Pfs230 domain one and Pfs48/45 domain three in Plasmodium falciparum parasites from western Kenya. Methods: Dry blood spots on filter paper were collected from febrile malaria patients reporting to community health facilities in endemic areas of Homa Bay and Kisumu Counties and an epidemic-prone area of Kisii County in 2018 and 2019. Plasmodium speciation was performed using eluted DNA and real-time PCR. Amplification of the target domains of the two Pfs genes was performed on P. falciparum positive samples. We sequenced Pfs230 domain one on 156 clinical isolates and Pfs48/45 domain three on 118 clinical isolates to infer the levels of genetic variability, signatures of selection, genetic diversity indices and perform other evolutionary analyses. Results: Pfs230 domain one had low nucleotide diversity (π = 0.15 × 10-2) with slight variation per study site. Six polymorphic sites with nonsynonymous mutations and eight haplotypes were discovered. I539T was a novel variant, whereas G605S was nearing fixation. Pfs48/45 domain three had a low π (0.063 × 10-2), high conservation index, and three segregating sites, resulting in nonsynonymous mutation and four haplotypes. Some loci of Pfs230 D1 were in positive or negative linkage disequilibrium, had negative or positive selection signatures, and others (1813, 1955) and (1813, 1983) had a history of recombination. Mutated loci pairs in Pfs48/45 domain three had negative linkage disequilibrium, and some had negative and positive Tajima's D values with no history of recombination events. Conclusion: The two transmission blocking vaccine candidates have low nucleotide diversity, a small number of zone-specific variants, high nucleotide conservation index, and high frequency of rare alleles. With the near fixation a polymorphic site and the proximity of mutated codons to antibody binding epitopes, it will be necessary to continue monitoring sequence modifications of these domains when designing TBVs that include Pfs230 and Pfs48/45 antigens.
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Affiliation(s)
- Kevin O. Ochwedo
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Fredrick O. Ariri
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
- Department of Zoology, School of Physical and Biological Sciences, Maseno University, Kisumu, Kenya
| | - Wilfred O. Otambo
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
- Department of Zoology, School of Physical and Biological Sciences, Maseno University, Kisumu, Kenya
| | - Edwin O. Magomere
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
- Department of Biochemistry, Egerton University, Nakuru, Kenya
| | - Isaiah Debrah
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
- West Africa Centre for Cell Biology of Infectious Pathogen, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Accra, Ghana
| | - Shirley A. Onyango
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
- School of Zoological Sciences, Kenyatta University, Nairobi, Kenya
| | - Pauline W. Orondo
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Harrysone E. Atieli
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Sidney O. Ogolla
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Antony C. A. Otieno
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | - Wolfgang R. Mukabana
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Andrew K. Githeko
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California, Irvine, Irvine, CA, United States
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California, Irvine, Irvine, CA, United States
| | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California, Irvine, Irvine, CA, United States
| | - James W. Kazura
- Centre for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, United States
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