title: Characterisation of near-full length genome sequences of three South African human immunodeficiency virus type 1 subtype C isolates.
abstract: As subtype C is the most prevalent circulating human immunodeficiency virus type 1 (HIV-1) subtype internationally as well as locally in South Africa, more information on the biological nature and molecular characteristics of these viruses is required. Proviral DNA was isolated from primary cultures of three South African R5 isolates and the near-full length genome amplified by PCR. The resultant PCR product was cloned into the pCR-XL-TOPO vector and a representative clone from each isolate sequenced by primer walking. Phylogenetic analysis showed all three clones clustered within subtype C with a bootstrap value of 100%, and no recombination with other subtypes was identified by distance scan and bootscan analysis. Analysis of the potential coding regions revealed premature truncations of the second rev exon but no other potential structural distortions nor frameshift mutations in the open reading frames. All the clones contained three potential NF-kappaB binding sites, a feature unique to subtype C viruses. The tips of the V3 loops contained the GPGQ sequence motif characteristic of CCR5-utilising subtype C strains, as well as relatively low overall net positive charge characteristic of non-syncytium-inducing isolates. This information contributes to our overall knowledge of circulating strains in South Africa and to the making of effective vaccines and chemotherapeutic agents.
authors.affiliation: AIDS Virus Research Unit, National Institute for Communicable Diseases and Department of Virology, University of the Witwatersrand, Johannesburg, South Africa. gillianh@niv.ac.za
authors.forename: Gillian M
authors.initials: GM
authors.lastname: Hunt
authors.forename: Maria A
authors.initials: MA
authors.lastname: Papathanasopoulos
authors.forename: Glenda E
authors.initials: GE
authors.lastname: Gray
authors.forename: Caroline T
authors.initials: CT
authors.lastname: Tiemessen
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D004279:DNA, Viral / Q000302:isolation & purification; D014644:Genetic Variation; D016679:Genome, Viral; D015699:HIV Envelope Protein gp120 / Q000235:genetics; D015658:HIV Infections / Q000453:epidemiology / Q000821:virology*; D015497:HIV-1 / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D010446:Peptide Fragments / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011533:Proviruses / Q000235:genetics; D012367:RNA, Viral / Q000235:genetics; D011995:Recombination, Genetic; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D013019:South Africa / Q000453:epidemiology
chemical_list: D004279:DNA, Viral; D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D016328:NF-kappa B; D010446:Peptide Fragments; D012367:RNA, Viral