Malaria transmission-blocking activity in experimental infections of Anopheles gambiae from naturally infected Plasmodium falciparum gametocyte carriers

ABSTRACTProduction of Pfs25, aPlasmodium falciparumtransmission-blocking vaccine target antigen, in functional conformation with the potential to elicit effective immunogenicity still remains a major challenge. In the current study, codon-harmonized recombinant Pfs25 (CHrPfs25) was expressed inEscherichia coli, and purified protein after simple oxidative refolding steps retained reduction-sensitive conformational epitopes of transmission-blocking monoclonal antibodies. CHrPfs25 formulated in several adjuvants elicited strong immunogenicity in preclinical studies in mice. Antibodies elicited after immunization recognized native Pfs25 on the surface of live gametes ofP. falciparumand demonstrated complete malaria transmission-blocking activity. The transmission-blocking efficacy was 100% even after a 1:128 dilution of sera from immunized mice in the complete Freund's adjuvant and Montanide ISA51 groups and after a 1:16 dilution of sera from mice in the alum group. The blocking was mediated by antibodies; purified IgG at concentrations as low as 31.25 μg/ml exhibited 100% transmission blocking in membrane feeding assays employing two different species of mosquitoes,Anopheles gambiaeandAnopheles stephensi. This study provides the first evidence for successful expression of biologically functional rPfs25 inE. coli. The extremely potent malaria transmission-blocking activity of antibodies elicited by immunization with purified protein provides strong support for further evaluation ofE. coli-derived CHrPfs25 as a malaria transmission-blocking vaccine in human clinical trials.

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Effect of naturally occurring Wolbachia in Anopheles gambiae s.l. mosquitoes from Mali on Plasmodium falciparum malaria transmission

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1716181114 ◽

2017 ◽

Vol 114 (47) ◽

pp. 12566-12571 ◽

Cited By ~ 44

Author(s):

Fabio M. Gomes ◽

Bretta L. Hixson ◽

Miles D. W. Tyner ◽

Jose Luis Ramirez ◽

Gaspar E. Canepa ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Anopheles Gambiae ◽

Malaria Transmission ◽

Deleterious Effect ◽

Plasmodium Falciparum Malaria ◽

Anopheles Coluzzii ◽

Naturally Occurring ◽

Anopheles Gambiae S.L ◽

Cat Fleas ◽

Sporozoite Infection

A naturally occurring Wolbachia strain (wAnga-Mali) was identified in mosquitoes of the Anopheles gambiae complex collected in the Malian villages of Dangassa and Kenieroba. Phylogenetic analysis of the nucleotide sequence of two 16S rRNA regions showed that wAnga-Mali clusters with Wolbachia strains from supergroup A and has the highest homology to a Wolbachia strain isolated from cat fleas (Ctenocephalides). wAnga-Mali is different from two Wolbachia strains previously reported in A. gambiae from Burkina Faso (wAnga_VK5_STP and wAnga_VK5_3.1a). Quantitative analysis of Wolbachia and Plasmodium sporozoite infection in field-collected mosquitoes indicates that the prevalence and intensity of Plasmodium falciparum sporozoite infection is significantly lower in Wolbachia-infected females. The presence of Wolbachia in females from a laboratory Anopheles coluzzii (A. gambiae, M form) colony experimentally infected with P. falciparum (NF54 strain) gametocyte cultures slightly enhanced oocyst infection. However, Wolbachia infection significantly reduced the prevalence and intensity of sporozoite infection, as observed in the field. This indicates that wAnga-Mali infection does not limit early stages of Plasmodium infection in the mosquito, but it has a strong deleterious effect on sporozoites and reduces malaria transmission.

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A Comparison of Transmission-Blocking Activity with Reactivity in a Plasmodium falciparum 48/45-kD Molecule-Specific Competition Enzyme-Linked Immunosorbent Assay

American Journal of Tropical Medicine and Hygiene ◽

10.4269/ajtmh.1995.52.60 ◽

1995 ◽

Vol 52 (1) ◽

pp. 60-65 ◽

Cited By ~ 29

Author(s):

W. Roeffen ◽

R. Sauerwein ◽

T. Lensen ◽

J. Van Druten ◽

B. Mulder ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Immunosorbent Assay ◽

Enzyme Linked Immunosorbent Assay ◽

Transmission Blocking ◽

Blocking Activity

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DSM265 at 400 Milligrams Clears Asexual Stage Parasites but Not Mature Gametocytes from the Blood of Healthy Subjects Experimentally Infected with Plasmodium falciparum

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01837-18 ◽

2019 ◽

Vol 63 (4) ◽

Cited By ~ 10

Author(s):

Katharine A. Collins ◽

Thomas Rückle ◽

Suzanne Elliott ◽

Louise Marquart ◽

Emma Ballard ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Pharmacodynamic Modeling ◽

Dihydroorotate Dehydrogenase ◽

Transmission Blocking ◽

Content Type ◽

Blocking Activity ◽

Cutaneous Rash ◽

Phase 1B ◽

Study Support ◽

Previous Phase

ABSTRACT DSM265 is a novel antimalarial drug in clinical development that acts as a selective inhibitor of Plasmodium dihydroorotate dehydrogenase. In a previous phase 1b study, a single 150-mg dose of DSM265 showed partial efficacy against experimentally induced blood-stage Plasmodium falciparum malaria (IBSM). Pharmacokinetic/pharmacodynamic modeling predicted a human efficacious dose of 340 mg. The primary objectives of the current study were to determine the safety and efficacy of a single oral 400-mg dose of DSM265 against P. falciparum in the IBSM model. Eight healthy participants were inoculated intravenously with 2,800 parasites and treated with DSM265 7 days later. Unexpectedly, one participant did not develop parasitemia during the study. All other participants developed parasitemia, with the complete clearance of asexual parasites occurring following DSM265 treatment. All seven subjects also became gametocytemic. The secondary objectives were to investigate the gametocytocidal and transmission-blocking activity of a second 400-mg dose of DSM265, which was administered 23 days after inoculation. Gametocytes were not cleared by the second dose of DSM265, and transmission-blocking activity could not be determined due to low gametocyte densities. Three DSM265-related adverse events occurred, including a cutaneous rash in one subject on the day of the second DSM265 dose. The results obtained in this study support the prediction of the efficacious dose of DSM265 and provide further evidence that DSM265 is generally safe and well tolerated. In addition, this study confirms preclinical data indicating that DSM265 permits the development and maturation of gametocytes and does not clear mature circulating gametocytes. (This study has been registered at ClinicalTrials.gov under identifier NCT02573857.)

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Recombinant Pfs25 protein of Plasmodium falciparum elicits malaria transmission-blocking immunity in experimental animals

Parasitology Today ◽

10.1016/0169-4758(92)90082-d ◽

1992 ◽

Vol 8 (2) ◽

pp. 43

Keyword(s):

Plasmodium Falciparum ◽

Malaria Transmission ◽

Transmission Blocking ◽

Experimental Animals

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Engineering a Virus-Like Particle as an Antigenic Platform for a Pfs47-Targeted Malaria Transmission-Blocking Vaccine

Scientific Reports ◽

10.1038/s41598-019-53208-z ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

Lampouguin Yenkoidiok-Douti ◽

Adeline E. Williams ◽

Gaspar E. Canepa ◽

Alvaro Molina-Cruz ◽

Carolina Barillas-Mury

Keyword(s):

Plasmodium Falciparum ◽

Amino Acid ◽

Malaria Transmission ◽

Transmission Blocking ◽

High Affinity ◽

Virus Like Particle ◽

Antibody Titers ◽

Reducing Activity ◽

Sexual Stages ◽

Transmission Blocking Vaccine

AbstractWe recently characterized Pfs47, a protein expressed on the surface of sexual stages and ookinetes of Plasmodium falciparum, as a malaria transmission-blocking vaccine (TBV) target. Mice immunization induced antibodies that conferred strong transmission-reducing activity (TRA) at a concentration of 200 μg/mL. Here, we sought to optimize the Pfs47 vaccine to elicit higher titers of high-affinity antibodies, capable of inducing strong TRA at a lower concentration. We report the development and evaluation of a Pfs47-based virus-like particle (VLP) vaccine generated by conjugating our 58 amino acid Pfs47 antigen to Acinetobacter phage AP205-VLP using the SpyCatcher:SpyTag adaptor system. AP205-Pfs47 complexes (VLP-P47) formed particles of ~22 nm diameter that reacted with polyclonal anti-Pfs47 antibodies, indicating that the antigen was accessible on the surface of the particle. Mice immunized with VLP-P47 followed by a boost with Pfs47 monomer induced significantly higher antibody titers, with higher binding affinity to Pfs47, than mice that received two immunizations with either VLP-P47 (VLP-P47/VLP-P47) or the Pfs47 monomer (P47/P47). Purified IgG from VLP-P47/P47 mice had strong TRA (83–98%) at concentrations as low as 5 μg/mL. These results indicate that conjugating the Pfs47 antigen to AP205-VLP significantly enhanced antigenicity and confirm the potential of Pfs47 as a TBV candidate.

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Comparison and Optimization of Different Methods for theIn VitroProduction ofPlasmodium falciparumGametocytes

Journal of Parasitology Research ◽

10.1155/2012/927148 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 17

Author(s):

María Roncalés ◽

Jaume Vidal-Mas ◽

Didier Leroy ◽

Esperanza Herreros

Keyword(s):

Plasmodium Falciparum ◽

Malaria Transmission ◽

Improved Method ◽

Transmission Blocking ◽

Blocking Malaria Transmission

The generation of sexually committed parasites (gametocytogenesis) is poorly understood in malaria. If the mechanisms regulating this process were elucidated, new opportunities for blocking malaria transmission could be revealed. Here we compare several methods described previously for thein vitroproduction ofPlasmodium falciparumgametocytes. Our approach relies on the combination of several factors that we demonstrated as impacting on or being critical to gametocytogenesis. An improved method has been developed for thein vitroproduction ofP. falciparumgametocytes as the first step toward obtaining adequate numbers of pure gametocytes forin vitrostudies, such as, for example, the identification of transmission blocking drugs.

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