title: HIV-1 subtype C Pr55gag virus-like particle vaccine efficiently boosts baboons primed with a matched DNA vaccine.
abstract: A DNA vaccine expressing human immunodeficiency virus type 1 (HIV-1) southern African subtype C Gag (pTHGag) and a recombinant baculovirus Pr55gag virus-like particle prepared using a subtype C Pr55gag protein (Gag VLP) was tested in a prime-boost inoculation regimen in Chacma baboons. The response of five baboons to Gag peptides in a gamma interferon (IFN-gamma) enzyme-linked immunospot (ELISPOT) assay after three pTHGag immunizations ranged from 100 to 515 spot-forming units (s.f.u.) per 10(6) peripheral blood mononuclear cells (PBMCs), whilst the response of two baboons to the Gag VLP vaccine ranged from 415 to 465 s.f.u. per 10(6) PBMCs. An increase in the Gag-specific response to a range of 775-3583 s.f.u. per 10(6) PBMCs was achieved by boosting with Gag VLPs the five baboons that were primed with pTHGag. No improvement in Gag responses was achieved in this prime-boost inoculation regimen by increasing the number of pTHGag inoculations to six. IFN-gamma responses were mapped to several peptides, some of which have been reported to be targeted by PBMCs from HIV-1 subtype C-infected individuals. Gag VLPs, given as a single-modality regimen, induced a predominantly CD8+ T-cell IFN-gamma response and interleukin-2 was a major cytokine within a mix of predominantly Th1 cytokines produced by a DNA-VLP prime-boost modality. The prime-boost inoculation regimen induced high serum p24 antibody titres in all baboons, which were several fold above that induced by the individual vaccines. Overall, this study demonstrated that these DNA prime/VLP boost vaccine regimens are highly immunogenic in baboons, inducing high-magnitude and broad multifunctional responses, providing support for the development of these products for clinical trials.
authors.affiliation: Institute of Primate Research, PO Box 24481, Karen 00502, Nairobi, Kenya.|Medical Virology, Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Rondebosch, Cape Town, South Africa.
authors.forename: Gerald K
authors.initials: GK
authors.lastname: Chege
authors.affiliation: MRC/UCT Liver Research Centre, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Rondebosch, Cape Town, South Africa.|Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Rondebosch, Cape Town, South Africa.
authors.forename: Enid G
authors.initials: EG
authors.lastname: Shephard
authors.affiliation: Department of Molecular and Cell Biology, Faculty of Science, University of Cape Town, Rondebosch, Cape Town, South Africa.|Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Rondebosch, Cape Town, South Africa.
authors.forename: Ann
authors.initials: A
authors.lastname: Meyers
authors.affiliation: Medical Virology, Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Rondebosch, Cape Town, South Africa.
authors.forename: Joanne
authors.initials: J
authors.lastname: van Harmelen
authors.affiliation: Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Rondebosch, Cape Town, South Africa.|Medical Virology, Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Rondebosch, Cape Town, South Africa.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Williamson
authors.affiliation: Department of Molecular and Cell Biology, Faculty of Science, University of Cape Town, Rondebosch, Cape Town, South Africa.
authors.forename: Alisson
authors.initials: A
authors.lastname: Lynch
authors.affiliation: National Institute for Communicable Diseases, Private Bag X4, Sandringham 2131, Johannesburg, South Africa.
authors.forename: Clive M
authors.initials: CM
authors.lastname: Gray
authors.affiliation: Department of Molecular and Cell Biology, Faculty of Science, University of Cape Town, Rondebosch, Cape Town, South Africa.|Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Rondebosch, Cape Town, South Africa.
authors.forename: Edward P
authors.initials: EP
authors.lastname: Rybicki
authors.affiliation: National Health Laboratory Service, Groote Schuur Hospital, Observatory, Cape Town, South Africa.|Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Rondebosch, Cape Town, South Africa.|Medical Virology, Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Rondebosch, Cape Town, South Africa.
authors.forename: Anna-Lise
authors.initials: AL
authors.lastname: Williamson