title: Alga-produced malaria transmission-blocking vaccine candidate Pfs25 formulated with a human use-compatible potent adjuvant induces high-affinity antibodies that block Plasmodium falciparum infection of mosquitoes.
abstract: A vaccine to prevent the transmission of malaria parasites from infected humans to mosquitoes is an important component for the elimination of malaria in the 21st century, yet it remains neglected as a priority of malaria vaccine development. The lead candidate for Plasmodium falciparum transmission-blocking vaccine development, Pfs25, is a sexual stage surface protein that has been produced for vaccine testing in a variety of heterologous expression systems. Any realistic malaria vaccine will need to optimize proper folding balanced against cost of production, yield, and potentially reactogenic contaminants. Here Chlamydomonas reinhardtii microalga-produced recombinant Pfs25 protein was formulated with four different human-compatible adjuvants (alum, Toll-like receptor 4 [TLR-4] agonist glucopyranosal lipid A [GLA] plus alum, squalene-oil-in-water emulsion, and GLA plus squalene-oil-in-water emulsion) and compared for their ability to induce malaria transmission-blocking antibodies. Alga-produced recombinant Pfs25 plus GLA plus squalene-oil-in-water adjuvant induced the highest titer and avidity in IgG antibodies, measured using alga-produced recombinant Pfs25 as the enzyme-linked immunosorbent assay (ELISA) antigen. These antibodies specifically reacted with the surface of P. falciparum macrogametes and zygotes and effectively prevented parasites from developing within the mosquito vector in standard membrane feeding assays. Alga-produced Pfs25 in combination with a human-compatible adjuvant composed of a TLR-4 agonist in a squalene-oil-in-water emulsion is an attractive new vaccine candidate that merits head-to-head comparison with other modalities of vaccine production and administration.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, California, USA.
authors.forename: Kailash P
authors.initials: KP
authors.lastname: Patra
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, California, USA.
authors.forename: Fengwu
authors.initials: F
authors.lastname: Li
authors.affiliation: Infectious Disease Research Institute, Seattle, Washington, USA.
authors.forename: Darrick
authors.initials: D
authors.lastname: Carter
authors.affiliation: Infectious Disease Research Institute, Seattle, Washington, USA.
authors.forename: James A
authors.initials: JA
authors.lastname: Gregory
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, California, USA.
authors.forename: Sheyenne
authors.initials: S
authors.lastname: Baga
authors.affiliation: Infectious Disease Research Institute, Seattle, Washington, USA.
authors.forename: Steven G
authors.initials: SG
authors.lastname: Reed
authors.affiliation: Division of Biological Science and the San Diego Center for Algae Biotechnology, University of California San Diego, La Jolla, California, USA.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Mayfield
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, California, USA jvinetz@ucsd.edu.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Vinetz
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000915:Antibody Affinity; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism; D009033:Culicidae / Q000469:parasitology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D017780:Malaria Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D008807:Mice, Inbred BALB C; D010963:Plasmodium falciparum / Q000276:immunology* / Q000302:isolation & purification; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D016896:Treatment Outcome; D022223:Vaccines, Subunit / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification
chemical_list: D000276:Adjuvants, Immunologic; D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D017780:Malaria Vaccines; C071284:Pfs25 protein, Plasmodium falciparum; D015800:Protozoan Proteins; D022223:Vaccines, Subunit; D014614:Vaccines, Synthetic