title: Characterization and selection of HIV-1 subtype C isolates for use in vaccine development.
abstract: HIV-1 genetic diversity among circulating strains presents a major challenge for HIV-1 vaccine development, particularly for developing countries where less sequence information is available. To identify representative viruses for inclusion in candidate vaccines targeted for South Africa, we applied an efficient sequence survey strategy to samples from recently and chronically infected persons residing in potential vaccine trial sites. All 111 sequences were subtype C, including 30 partial gag, 26 partial pol, 27 V2-V3 env, and 28 V5-partial gp41 sequences. Of the 10 viruses cultured from recently infected individuals, 9 were R5 and 1 was R5X4. Two isolates, Du151 and Du422, collected within 2 months of infection, were selected as vaccine strains on the basis of their amino acid similarity to a derived South African consensus sequence The selection of recently transmitted R5 isolates for vaccine design may provide an advantage in a subtype C R5-dominant epidemic. The full-length Du422 gag and Du151 pol and env genes were cloned into the Venezuelan equine encephalitis (VEE) replicon particle (VRP) expression system. Du422 Gag protein expressed from the VRP accumulated to a high level and was immunogenic as demonstrated by cytotoxic T lymphocyte responses in mice vaccinated with gag-VRPs. Optimization of codon use for VRP expression in human cells did not enhance expression of the gag gene. The cloned Du151 env gene encoded a functional protein as demonstrated by fusion of VRP-infected cells with cells expressing CD4 and CCR5. Genes identified in this study have been incorporated into the VEE VRP candidate vaccines targeted for clinical trial in South Africa.
authors.affiliation: Division of Medical Virology, University of Cape Town, Observatory, Cape Town, South Africa 7925. cwilliam@curie.uct.ac.za
authors.forename: Carolyn
authors.initials: C
authors.lastname: Williamson
authors.forename: Lynn
authors.initials: L
authors.lastname: Morris
authors.forename: Maureen F
authors.initials: MF
authors.lastname: Maughan
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Ping
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Dryga
authors.forename: Robin
authors.initials: R
authors.lastname: Thomas
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Reap
authors.forename: Tonie
authors.initials: T
authors.lastname: Cilliers
authors.forename: Joanne
authors.initials: J
authors.lastname: van Harmelen
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual
authors.forename: Gita
authors.initials: G
authors.lastname: Ramjee
authors.forename: Glenda
authors.initials: G
authors.lastname: Gray
authors.forename: Robert
authors.initials: R
authors.lastname: Johnston
authors.forename: Salim Abdool
authors.initials: SA
authors.lastname: Karim
authors.forename: Ronald
authors.initials: R
authors.lastname: Swanstrom
mesh_terms: D016915:AIDS Vaccines; D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D002986:Clinical Trials as Topic; D004666:Encephalitis Virus, Venezuelan Equine / Q000235:genetics; D015686:Gene Products, env / Q000235:genetics / Q000378:metabolism; D015683:Gene Products, gag / Q000235:genetics / Q000378:metabolism; D005822:Genetic Vectors; D015658:HIV Infections / Q000517:prevention & control*; D015497:HIV-1 / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D012093:Replicon / Q000235:genetics; D017422:Sequence Analysis, DNA; D013019:South Africa; D014709:Vero Cells; D014771:Virion / Q000235:genetics / Q000378:metabolism
chemical_list: D016915:AIDS Vaccines; D015686:Gene Products, env; D015683:Gene Products, gag