title: Functional evaluation of malaria Pfs25 DNA vaccine by in vivo electroporation in olive baboons.
abstract: Plasmodium falciparum Pfs25 antigen, expressed on the surface of zygotes and ookinetes, is one of the leading targets for the development of a malaria transmission-blocking vaccine (TBV). Our laboratory has been evaluating DNA plasmid based Pfs25 vaccine in mice and non-human primates. Previously, we established that in vivo electroporation (EP) delivery is an effective method to improve the immunogenicity of DNA vaccine encoding Pfs25 in mice. In order to optimize the in vivo EP procedure and test for its efficacy in more clinically relevant larger animal models, we employed in vivo EP to evaluate the immune response and protective efficacy of Pfs25 encoding DNA vaccine in nonhuman primates (olive baboons, Papio anubis). The results showed that at a dose of 2.5mg DNA vaccine, antibody responses were significantly enhanced with EP as compared to without EP resulting in effective transmission blocking efficiency. Similar immunogenicity enhancing effect of EP was also observed with lower doses (0.5mg and 1mg) of DNA plasmids. Further, final boosting with a single dose of recombinant Pfs25 protein resulted in dramatically enhanced antibody titers and significantly increased functional transmission blocking efficiency. Our study suggests priming with DNA vaccine via EP along with protein boost regimen as an effective method to elicit potent immunogenicity of malaria DNA vaccines in nonhuman primates and provides the basis for further evaluation in human volunteers.
authors.affiliation: Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, 1440 Canal Street (SL-17), New Orleans, LA 70112, USA.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Kumar
authors.forename: Ruth
authors.initials: R
authors.lastname: Nyakundi
authors.forename: Thomas
authors.initials: T
authors.lastname: Kariuki
authors.forename: Hastings
authors.initials: H
authors.lastname: Ozwara
authors.forename: Onkoba
authors.initials: O
authors.lastname: Nyamongo
authors.forename: Godfree
authors.initials: G
authors.lastname: Mlambo
authors.forename: Barry
authors.initials: B
authors.lastname: Ellefsen
authors.forename: Drew
authors.initials: D
authors.lastname: Hannaman
authors.forename: Nirbhay
authors.initials: N
authors.lastname: Kumar
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D000915:Antibody Affinity; D000917:Antibody Formation; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D018274:Electroporation; D005260:Female; D007117:Immunization, Secondary; D017780:Malaria Vaccines / Q000008:administration & dosage* / Q000235:genetics / Q000276:immunology; D016778:Malaria, Falciparum / Q000276:immunology / Q000517:prevention & control*; D051379:Mice; D048530:Papio anubis / Q000276:immunology; D010957:Plasmids; D010963:Plasmodium falciparum; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D019444:Vaccines, DNA / Q000008:administration & dosage* / Q000235:genetics / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D017780:Malaria Vaccines; C071284:Pfs25 protein, Plasmodium falciparum; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D019444:Vaccines, DNA