scholarly journals Monoclonal Antibody against the Plasmodium falciparum Chitinase, PfCHT1, Recognizes a Malaria Transmission-Blocking Epitope in Plasmodium gallinaceum Ookinetes Unrelated to the Chitinase PgCHT1

2002 ◽  
Vol 70 (3) ◽  
pp. 1581-1590 ◽  
Author(s):  
Rebecca C. Langer ◽  
Fengwu Li ◽  
Vsevolod Popov ◽  
Alexander Kurosky ◽  
Joseph M. Vinetz
Keyword(s):  
Monoclonal Antibody ◽  
Plasmodium Falciparum ◽  
Synthetic Peptide ◽  
Transmission Blocking ◽  
Reducing Conditions ◽  
Membrane Feeding ◽  
Epithelial Cell Surface ◽  
A Subunit ◽  
35 Kda Protein ◽  
Homologous Amino Acid

ABSTRACT To initiate invasion of the mosquito midgut, Plasmodium ookinetes secrete chitinases that are necessary to cross the chitin-containing peritrophic matrix en route to invading the epithelial cell surface. To investigate chitinases as potential immunological targets of blocking malaria parasite transmission to mosquitoes, a monoclonal antibody (MAb) was identified that neutralized the enzymatic activity of the sole chitinase of Plasmodium falciparum, PfCHT1, identified to date. This MAb, designated 1C3, previously shown to react with an apical structure of P. falciparum ookinetes, also reacts with a discrete apical structure of P. gallinaceum ookinetes. In membrane feeding assays, MAb 1C3 markedly inhibited P. gallinaceum oocyst development in mosquito midguts. MAb 1C3 affinity isolated an ∼210-kDa antigen which, under reducing conditions, became a 35-kDa antigen. This isolated 35-kDa protein cross-reacted with an antiserum raised against a synthetic peptide derived from the P. gallinaceum chitinase active site, PgCHT1, even though MAb 1C3 did not recognize native or recombinant PgCHT1 on Western blot. Therefore, this affinity-purified 35-kDa antigen appears similar to a previously identified protein, PgCHT2, a putative second chitinase of P. gallinaceum. Epitope mapping indicated MAb 1C3 recognized a region of PfCHT1 that diverges from a homologous amino acid sequence conserved within sequenced chitinases of P. berghei, P. yoelii, and P. gallinaceum (PgCHT1). A synthetic peptide derived from the mapped 1C3 epitope may be useful as a component of a subunit transmission-blocking vaccine.

Plasmodium falciparum Pf77 and male development gene 1 as vaccine antigens that induce potent transmission-reducing antibodies

2021 ◽  
Vol 13 (597) ◽  
pp. eabg2112
Author(s):  
Abhai K. Tripathi ◽  
Miranda S. Oakley ◽  
Nitin Verma ◽  
Godfree Mlambo ◽  
Hong Zheng ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Phase 1 ◽  
Biological Properties ◽  
Natural Immunity ◽  
Specific Expression ◽  
Transmission Blocking ◽  
Male Development ◽  
Malaria Vaccines ◽  
Membrane Feeding ◽  
Vaccine Antigens

Malaria vaccines that disrupt the Plasmodium life cycle in mosquitoes and reduce parasite transmission in endemic areas are termed transmission-blocking vaccines (TBVs). Despite decades of research, there are only a few Plasmodium falciparum antigens that indisputably and reproducibly demonstrate transmission-blocking immunity. So far, only two TBV candidates have advanced to phase 1/2 clinical testing with limited success. By applying an unbiased transcriptomics-based approach, we have identified Pf77 and male development gene 1 (PfMDV-1) as two P. falciparum TBV antigens that, upon immunization, induced antibodies that caused reductions in oocyst counts in Anopheles mosquito midguts in a standard membrane feeding assay. In-depth studies were performed to characterize the genetic diversity of, stage-specific expression by, and natural immunity to these two molecules to evaluate their suitability as TBV candidates. Pf77 and PfMDV-1 display limited antigenic polymorphism, are pan-developmentally expressed within the parasite, and induce naturally occurring antibodies in Ghanaian adults, which raises the prospect of natural boosting of vaccine-induced immune response in endemic regions. Together, these biological properties suggest that Pf77 and PfMDV-1 may warrant further investigation as TBV candidates.

scholarly journals Transmission-Blocking Activities of Quinine, Primaquine, and Artesunate

2006 ◽  
Vol 50 (6) ◽  
pp. 1927-1930 ◽  
Author(s):  
Kesinee Chotivanich ◽  
Jetsumon Sattabongkot ◽  
Rachanee Udomsangpetch ◽  
Sornchai Looareesuwan ◽  
Nicholas P. J. Day ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Standard Deviation ◽  
Anopheles Dirus ◽  
Transmission Blocking ◽  
Transmission Potential ◽  
Membrane Feeding ◽  
Blocking Activity ◽  
The Mean ◽  
High Concentrations

ABSTRACT The infectivity of Plasmodium falciparum gametocytes after exposure in vitro to quinine, artesunate, and primaquine was assessed in Anopheles dirus, a major vector of malaria in Southeast Asia. Mature gametocytes (stage 5) of a Thai isolate of P. falciparum were exposed to the drugs for 24 h in vitro before membrane feeding to A. dirus. After 10 days, the mosquito midguts were dissected and the oocysts were counted. In this system, artesunate showed the most potent transmission-blocking activity; the mean (standard deviation [SD]) 50% and 90% effective concentrations (EC50, and EC90, respectively, in nanograms per milliliter) were 0.1 (0.02) and 0.4 (0.15), respectively. Transmission-blocking activity of quinine and primaquine was observed at relatively high concentrations (SDs): EC50 of quinine, 642 (111) ng/ml; EC50 of primaquine, 181 (23) ng/ml; EC90 of quinine, 816 (96) ng/ml; EC90 of primaquine, 543 (43) ng/ml. Artesunate both prevents the maturation of immature P. falciparum gametocytes and reduces the transmission potential of mature gametocytes. Both of these effects may contribute to reducing malaria transmission.

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

npj Vaccines ◽  
2022 ◽  
Vol 7 (1) ◽  
Author(s):  
Kazutoyo Miura ◽  
Eizo Takashima ◽  
Thao P. Pham ◽  
Bingbing Deng ◽  
Luwen Zhou ◽  
...  
Keyword(s):  
Malaria Transmission ◽  
Synthetic Peptide ◽  
Vaccine Antigen ◽  
Parasite Development ◽  
Transmission Blocking ◽  
Peptide Antigens ◽  
Membrane Feeding ◽  
Functional Antibodies ◽  
Enrichment Techniques ◽  
Transmission Blocking Vaccine

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.

scholarly journals Induction of Plasmodium falciparum Transmission-Blocking Antibodies in Nonhuman Primates by a Combination of DNA and Protein Immunizations

2004 ◽  
Vol 72 (1) ◽  
pp. 253-259 ◽  
Author(s):  
Cevayir Coban ◽  
Mario T. Philipp ◽  
Jeanette E. Purcell ◽  
David B. Keister ◽  
Mobolaji Okulate ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Antibody Response ◽  
Dna Vaccine ◽  
Nonhuman Primates ◽  
Rhesus Macaques ◽  
Surface Protein ◽  
Mosquito Vector ◽  
Transmission Blocking ◽  
Membrane Feeding ◽  
Antibody Titers

ABSTRACT Malaria transmission-blocking vaccination can effectively reduce and/or eliminate transmission of parasites from the human host to the mosquito vector. The immunity achieved by inducing an antibody response to surface antigens of male and female gametes and parasite stages in the mosquito. Our laboratory has developed DNA vaccine constructs, based on Pfs25 (a Plasmodium falciparum surface protein of 25 kDa), that induce a transmission-blocking immune response in mice (C. A. Lobo, R. Dhar, and N. Kumar, Infect. Immun. 67:1688-1693, 1999). To evaluate the safety, immunogenicity, and efficacy of the Pfs25 DNA vaccine in nonhuman primates, we immunized rhesus macaques (Macaca mulatta) with a DNA vaccine plasmid encoding Pfs25 or a Pfg27-Pfs25 hybrid or with the plasmid (empty plasmid) alone. Immunization with four doses of these DNA vaccine constructs elicited antibody titers that were high but nonetheless unable to reduce the parasite's infectivity in membrane feeding assays. Further boosting of the antibody response with recombinant Pfs25 formulated in Montanide ISA-720 increased antibody titers (30-fold) and significantly blocked transmission of P. falciparum gametocytes to Anopheles mosquitoes (∼90% reduction in oocyst numbers in the midgut). Our data show that a DNA prime-protein boost regimen holds promise for achieving transmission-blocking immunity in areas where malaria is endemic and could be effective in eradicating malaria in isolated areas where the level of malaria endemicity is low.

scholarly journals Anti-Pfs25 Human Plasma Reduces Transmission of Plasmodium falciparum Isolates That Have Diverse Genetic Backgrounds

2013 ◽  
Vol 81 (6) ◽  
pp. 1984-1989 ◽  
Author(s):  
Dari F. Da ◽  
Saurabh Dixit ◽  
Jetsumon Sattabonkot ◽  
Jianbing Mu ◽  
Luc Abate ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Burkina Faso ◽  
Phase 1 ◽  
Transmission Blocking ◽  
Content Type ◽  
Phase 1 Trial ◽  
Membrane Feeding ◽  
Geographical Regions ◽  
Reducing Activity ◽  
Membrane Feeding Assay

ABSTRACTPfs25 is a leading candidate for a malaria transmission-blocking vaccine whose potential has been demonstrated in a phase 1 trial with recombinant Pfs25 formulated with Montanide ISA51. Because of limited sequence polymorphism, the anti-Pfs25 antibodies induced by this vaccine are likely to have transmission-blocking or -reducing activity against most, if not all, field isolates. To test this hypothesis, we evaluated transmission-blocking activities by membrane feeding assay of anti-Pfs25 plasma from the Pfs25/ISA51 phase 1 trial againstPlasmodium falciparumparasites from patients in two different geographical regions of the world, Thailand and Burkina Faso. In parallel, parasite isolates from these patients were sequenced for the Pfs25 gene and genotyped for seven microsatellites. The results indicate that despite different genetic backgrounds among parasite isolates, the Pfs25 sequences are highly conserved, with a single nonsynonymous nucleotide polymorphism detected in 1 of 41 patients in Thailand and Burkina Faso. The anti-Pfs25 immune plasma had significantly higher transmission-reducing activity against parasite isolates from the two geographical regions than the nonimmune controls (P< 0.0001).

scholarly journals Functional Comparison of Plasmodium falciparum Transmission-Blocking Vaccine Candidates by the Standard Membrane-Feeding Assay

2013 ◽  
Vol 81 (12) ◽  
pp. 4377-4382 ◽  
Author(s):  
Kazutoyo Miura ◽  
Eizo Takashima ◽  
Bingbing Deng ◽  
Gregory Tullo ◽  
Ababacar Diouf ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Recombinant Proteins ◽  
The Other ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dependent Manner ◽  
Feeding Assay ◽  
Transmission Blocking ◽  
Content Type ◽  
Membrane Feeding ◽  
Membrane Feeding Assay

ABSTRACTRecently, there has been a renewed interest in the development of transmission-blocking vaccines (TBV) againstPlasmodium falciparummalaria. While several candidate TBVs have been reported, studies directly comparing them in functional assays are limited. To this end, recombinant proteins of TBV candidates Pfs25, Pfs230, and PfHAP2 were expressed in the wheat germ cell-free expression system. Outbred CD-1 mice were immunized twice with the antigens. Two weeks after the second immunization, IgG levels were measured by enzyme-linked immunosorbent assay (ELISA), and IgG functionality was assessed by the standard membrane-feeding assay (SMFA) using culturedP. falciparumNF54 gametocytes andAnopheles stephensimosquitoes. All three recombinant proteins elicited similar levels of antigen-specific IgG judged by ELISA. When IgGs purified from pools of immune serum were tested at 0.75 mg/ml in the SMFA, all three IgGs showed 97 to 100% inhibition in oocyst intensity compared to control IgG. In two additional independent SMFA evaluations, anti-Pfs25, anti-Pfs230, and anti-PfHAP2 IgGs inhibited oocyst intensity in a dose-dependent manner. When all three data sets were analyzed, anti-Pfs25 antibody showed significantly higher inhibition than the other two antibodies (P< 0.001 for both), while there was no significant difference between the other two (P= 0.15). A proportion of plasma samples collected from adults living in an area of malaria endemicity in Mali recognized Pfs230 and PfHAP2. This is the first study showing that the HAP2 protein ofP. falciparumcan induce transmission-blocking antibody. The current study supports the possibility of using this system for a comparative study with multiple TBV candidates.

scholarly journals A Plant-Produced Pfs230 Vaccine Candidate Blocks Transmission of Plasmodium falciparum

2011 ◽  
Vol 18 (8) ◽  
pp. 1351-1357 ◽  
Author(s):  
Christine E. Farrance ◽  
Amy Rhee ◽  
R. Mark Jones ◽  
Konstantin Musiychuk ◽  
Moneim Shamloul ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Vaccine Candidate ◽  
Expression System ◽  
Leaf Tissue ◽  
Sexual Cycle ◽  
New Host ◽  
Transmission Blocking ◽  
Content Type ◽  
Block Transmission ◽  
Membrane Feeding

ABSTRACTPlasmodium falciparumis transmitted to a new host after completing its sexual cycle within a mosquito. Developing vaccines against the parasite sexual stages is a critical component in the fight against malaria. We are targeting multiple proteins ofP. falciparumwhich are found only on the surfaces of the sexual forms of the parasite and where antibodies against these proteins have been shown to block the progression of the parasite's life cycle in the mosquito and thus block transmission to the next human host. We have successfully produced a region of the Pfs230 antigen in our plant-based transient-expression system and evaluated this vaccine candidate in an animal model. This plant-produced protein, 230CMB, is expressed at approximately 800 mg/kg in fresh whole leaf tissue and is 100% soluble. Administration of 230CMB with >90% purity induces strong immune responses in rabbits with high titers of transmission-blocking antibodies, resulting in a greater than 99% reduction in oocyst counts in the presence of complement, as determined by a standard membrane feeding assay. Our data provide a clear perspective on the clinical development of a Pfs230-based transmission-blocking malaria vaccine.

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

2004 ◽  
Vol 72 (1) ◽  
pp. 584-588 ◽  
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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