Elucidating functional epitopes within the N-terminal region of malaria transmission blocking vaccine antigen Pfs230

AbstractPfs230 is a leading malaria transmission blocking vaccine (TBV) candidate. Comprising 3135 amino acids (aa), the large size of Pfs230 necessitates the use of sub-fragments as vaccine immunogens. Therefore, determination of which regions induce functional antibody responses is essential. We previously reported that of 27 sub-fragments spanning the entire molecule, only five induced functional antibodies. A “functional” antibody is defined herein as one that inhibits Plasmodium falciparum parasite development in mosquitoes in a standard membrane-feeding assay (SMFA). These five sub-fragments were found within the aa 443–1274 range, and all contained aa 543–730. Here, we further pinpoint the location of epitopes within Pfs230 that are recognized by functional antibodies using antibody depletion and enrichment techniques. Functional epitopes were not found within the aa 918–1274 region. Within aa 443–917, further analysis showed the existence of functional epitopes not only within the aa 543–730 region but also outside of it. Affinity-purified antibodies using a synthetic peptide matching aa 543–588 showed activity in the SMFA. Immunization with a synthetic peptide comprising this segment, formulated either as a carrier-protein conjugate vaccine or with a liposomal vaccine adjuvant system, induced antibodies in mice that were functional in the SMFA. These findings provide key insights for Pfs230-based vaccine design and establish the feasibility for the use of synthetic peptide antigens for a malaria TBV.

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Molecular definition of multiple sites of antibody inhibition of malaria transmission-blocking vaccine antigen Pfs25

Nature Communications ◽

10.1038/s41467-017-01924-3 ◽

2017 ◽

Vol 8 (1) ◽

Cited By ~ 23

Author(s):

Stephen W. Scally ◽

Brandon McLeod ◽

Alexandre Bosch ◽

Kazutoyo Miura ◽

Qi Liang ◽

...

Keyword(s):

Malaria Transmission ◽

Vaccine Antigen ◽

Transmission Blocking ◽

Definition Of ◽

Transmission Blocking Vaccine ◽

Antibody Inhibition

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N-Terminal Prodomain of Pfs230 Synthesized Using a Cell-Free System Is Sufficient To Induce Complement-Dependent Malaria Transmission-Blocking Activity

Clinical and Vaccine Immunology ◽

10.1128/cvi.05104-11 ◽

2011 ◽

Vol 18 (8) ◽

pp. 1343-1350 ◽

Cited By ~ 49

Author(s):

Mayumi Tachibana ◽

Yimin Wu ◽

Hideyuki Iriko ◽

Olga Muratova ◽

Nicholas J. MacDonald ◽

...

Keyword(s):

Malaria Transmission ◽

Expression System ◽

Surface Protein ◽

Western Blot Assay ◽

Free System ◽

Transmission Blocking ◽

Content Type ◽

Membrane Feeding ◽

Blocking Activity ◽

Transmission Blocking Vaccine

ABSTRACTThe aim of a malaria transmission-blocking vaccine is to block the development of malaria parasites in the mosquito and thus prevent subsequent infection of the human host. Previous studies have demonstrated that the gametocyte/gamete surface protein Pfs230 can induce transmission-blocking immunity and have evaluatedEscherichia coli-produced Pfs230 as a transmission-blocking vaccine candidate. In this study, we used the wheat germ cell-free expression system to produce N-terminal fragments of Pfs230 and evaluated the transmission-blocking activity of antisera raised against the recombinant Pfs230 protein. The rabbit antisera reacted to the surface of cultured gametocytes and gametes of thePlasmodium falciparumNF54 line, recognized the 360-kDa form of parasite-produced Pfs230 by Western blot assay, and reduced the infectivity of NF54 parasites toAnopheles stefensimosquitoes in the presence of complement in a standard membrane feeding assay. Thus, our data demonstrate that the N-terminal pro domain of Pfs230 is sufficient to induce complement-dependent transmission-blocking activity againstP. falciparum.

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The fibrinogen-like domain of FREP1 protein is a broad-spectrum malaria transmission-blocking vaccine antigen

Journal of Biological Chemistry ◽

10.1074/jbc.m116.773564 ◽

2017 ◽

Vol 292 (28) ◽

pp. 11960-11969 ◽

Cited By ~ 14

Author(s):

Guodong Niu ◽

Caio Franc̨a ◽

Genwei Zhang ◽

Wanlapa Roobsoong ◽

Wang Nguitragool ◽

...

Keyword(s):

Malaria Transmission ◽

Broad Spectrum ◽

Vaccine Antigen ◽

Transmission Blocking ◽

Transmission Blocking Vaccine

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Predicting the public health impact of a malaria transmission-blocking vaccine

Nature Communications ◽

10.1038/s41467-021-21775-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Joseph D. Challenger ◽

Daniela Olivera Mesa ◽

Dari F. Da ◽

R. Serge Yerbanga ◽

Thierry Lefèvre ◽

...

Keyword(s):

Public Health ◽

Malaria Transmission ◽

Health Impact ◽

Public Health Impact ◽

Substantial Impact ◽

Transmission Blocking ◽

Block Transmission ◽

Membrane Feeding ◽

Field Efficacy ◽

Transmission Blocking Vaccine

AbstractTransmission-blocking vaccines that interrupt malaria transmission from humans to mosquitoes are being tested in early clinical trials. The activity of such a vaccine is commonly evaluated using membrane-feeding assays. Understanding the field efficacy of such a vaccine requires knowledge of how heavily infected wild, naturally blood-fed mosquitoes are, as this indicates how difficult it will be to block transmission. Here we use data on naturally infected mosquitoes collected in Burkina Faso to translate the laboratory-estimated activity into an estimated activity in the field. A transmission dynamics model is then utilised to predict a transmission-blocking vaccine’s public health impact alongside existing interventions. The model suggests that school-aged children are an attractive population to target for vaccination. Benefits of vaccination are distributed across the population, averting the greatest number of cases in younger children. Utilising a transmission-blocking vaccine alongside existing interventions could have a substantial impact against malaria.

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Immunofocusing humoral immunity potentiates the functional efficacy of the AnAPN1 malaria transmission-blocking vaccine antigen

npj Vaccines ◽

10.1038/s41541-021-00309-4 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Nicole G. Bender ◽

Prachi Khare ◽

Juan Martinez ◽

Rebecca E. Tweedell ◽

Vincent O. Nyasembe ◽

...

Keyword(s):

Malaria Transmission ◽

Humoral Response ◽

Vaccine Antigen ◽

Mosquito Vector ◽

Transmission Blocking ◽

Cd1 Mice ◽

Alanyl Aminopeptidase ◽

Antigen Structure ◽

Transmission Blocking Vaccines ◽

Transmission Blocking Vaccine

AbstractMalaria transmission-blocking vaccines (TBVs) prevent the completion of the developmental lifecycle of malarial parasites within the mosquito vector, effectively blocking subsequent infections. The mosquito midgut protein Anopheline alanyl aminopeptidase N (AnAPN1) is the leading, mosquito-based TBV antigen. Structure-function studies identified two Class II epitopes that can induce potent transmission-blocking (T-B) antibodies, informing the design of the next-generation AnAPN1. Here, we functionally screened new immunogens and down-selected to the UF6b construct that has two glycine-linked copies of the T-B epitopes. We then established a process for manufacturing UF6b and evaluated in outbred female CD1 mice the immunogenicity of the preclinical product with the human-safe adjuvant Glucopyranosyl Lipid Adjuvant in a liposomal formulation with saponin QS21 (GLA-LSQ). UF6b:GLA-LSQ effectively immunofocused the humoral response to one of the key T-B epitopes resulting in potent T-B activity, underscoring UF6b as a prime TBV candidate to aid in malaria elimination and eradication efforts.

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Effect of CpG Oligodeoxynucleotides on the Immunogenicity of Pfs25, a Plasmodium falciparum Transmission-Blocking Vaccine Antigen

Infection and Immunity ◽

10.1128/iai.72.1.584-588.2004 ◽

2004 ◽

Vol 72 (1) ◽

pp. 584-588 ◽

Cited By ~ 23

Author(s):

Cevayir Coban ◽

Ken J. Ishii ◽

Anthony W. Stowers ◽

David B. Keister ◽

Dennis M. Klinman ◽

...

Keyword(s):

Plasmodium Falciparum ◽

High Titer ◽

Pathogen Transmission ◽

Vaccine Antigen ◽

Cpg Odn ◽

Transmission Blocking ◽

Cpg Oligodeoxynucleotides ◽

Membrane Feeding ◽

Antibody Levels ◽

Transmission Blocking Vaccine

ABSTRACT Antibodies directed against Pfs25, a protein present on the surface of zygotes and ookinetes of Plasmodium falciparum, completely block pathogen transmission. We evaluated the immunomodulatory effect of CpG oligodeoxynucleotides (ODN) on the immunogenicity of recombinant Pfs25 (rPfs25) formulated in alum (Al). Immunization of mice with rPfs25 plus CpG ODN improved both the antibody titer (a 30-fold-higher antibody response than that with rPfs25-Al alone) and avidity. Coadministration of CpG ODN dramatically enhanced the titer of immunoglobulin G2A (IgG2a) compared to the titer of the IgG1-dominant response caused by rPfs25-Al alone, and the sera from the CpG ODN-coadministered group completely blocked the transmission of P. falciparum parasites to mosquitoes, as determined by membrane feeding assays. However, transmission-blocking experiments revealed that blocking efficacy was dependent on high-titer antibody levels, independent of isotypes. These results suggest that CpG ODN can be used as an adjuvant to enhance the immunogenicity of rPfs25 as a malaria transmission-blocking vaccine.

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Immunofocusing humoral immunity potentiates the functional efficacy of the AnAPN1 malaria transmission-blocking vaccine antigen

10.1101/2020.11.29.402669 ◽

2020 ◽

Author(s):

Nicole G. Bender ◽

Prachi Khare ◽

Juan Martinez ◽

Rebecca E. Tweedell ◽

Vincent O. Nyasembe ◽

...

Keyword(s):

Malaria Transmission ◽

Malaria Elimination ◽

Humoral Response ◽

Vaccine Antigen ◽

Mosquito Vector ◽

Transmission Blocking ◽

Cd1 Mice ◽

Alanyl Aminopeptidase ◽

Transmission Blocking Vaccines ◽

Transmission Blocking Vaccine

AbstractMalaria transmission-blocking vaccines (TBVs) are a critical tool for disease elimination. TBVs prevent completion of the developmental lifecycle of malarial parasites within the mosquito vector, effectively blocking subsequent infections. The mosquito midgut protein Anopheline alanyl aminopeptidase N (AnAPN1) is the leading, mosquito-based TBV antigen and structure-function studies have identified two Class II epitopes that induce potent transmission-blocking (T-B) antibodies. Here, we functionally screened new immunogens and down-selected to the UF6b construct that has two glycine-linked copies of the T-B epitopes. We established a process for manufacturing UF6b and evaluated in outbred female CD1 mice the immunogenicity of the preclinical product with the human-safe adjuvant Glucopyranosyl Lipid Adjuvant in a liposomal formulation with saponin QS21 (GLA-LSQ). UF6b:GLA-LSQ was immunogenic and immunofocused the humoral response to one of the key T-B epitopes resulting in potent T-B activity and establishing UF6b as a prime TBV candidate to aid in malaria elimination and eradication efforts.

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Expression of malaria transmission-blocking vaccine antigen Pfs25 in Pichia pastoris for use in human clinical trials

Vaccine ◽

10.1016/s0264-410x(02)00701-6 ◽

2003 ◽

Vol 21 (15) ◽

pp. 1650-1657 ◽

Cited By ~ 49

Author(s):

Lanling Zou ◽

Aaron P Miles ◽

Jin Wang ◽

Anthony W Stowers

Keyword(s):

Clinical Trials ◽

Pichia Pastoris ◽

Malaria Transmission ◽

Vaccine Antigen ◽

Transmission Blocking ◽

Transmission Blocking Vaccine

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Preclinical development of a Pfs230-Pfs48/45 chimeric malaria transmission-blocking vaccine

npj Vaccines ◽

10.1038/s41541-021-00383-8 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Susheel K. Singh ◽

Jordan Plieskatt ◽

Bishwanath K. Chourasia ◽

Vandana Singh ◽

Karin Lövgren Bengtsson ◽

...

Keyword(s):

Malaria Transmission ◽

Clinical Evaluation ◽

Disulfide Bonds ◽

Expression System ◽

Mass Spectrometry Analysis ◽

Preclinical Development ◽

Transmission Blocking ◽

Spectrometry Analysis ◽

Functional Antibodies ◽

Transmission Blocking Vaccine

AbstractThe Plasmodium falciparum Pfs230 and Pfs48/45 proteins are leading candidates for a malaria transmission-blocking vaccine (TBV). Previously, we showed that a Pfs230–Pfs48/45 fusion protein elicits higher levels of functional antibodies than the individual antigens, but low yields hampered progression to clinical evaluation. Here we identified a modified construct (ProC6C) with a circumsporozoite protein (CSP) repeat-linker sequence that enhances expression. A scalable and reproducible process in the Lactococcus lactis expression system was developed and ProC6C was successfully transferred for manufacturing under current Good Manufacturing Practices (cGMP). In addition, a panel of analytical assays for release and stability were developed. Intact mass spectrometry analysis and multiangle light scattering showed that the protein contained correct disulfide bonds and was monomeric. Immunogenicity studies in mice showed that the ProC6C adsorbed to Alhydrogel®, with or without Matrix-MTM, elicited functional antibodies that reduced transmission to mosquitoes and sporozoite invasion of human hepatocytes. Altogether, our data support manufacture and clinical evaluation of ProC6C as a multistage malaria-vaccine candidate.

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