title: Apparent founder effect during the early years of the San Francisco HIV type 1 epidemic (1978-1979).
abstract: HIV-1 envelope sequence variants were RT-PCR amplified from serum samples cryopreserved in San Francisco in 1978-1979. The HIV-1 subtype B env V3-V5 sequences from four homosexual men clustered phylogenetically, with a median nucleotide distance of 2.8%, reflecting a recent common origin. These early U.S. HIV-1 env variants mapped close to the phylogenetic root of the subtype B tree while env variants collected in the United States throughout the 1980s and 1990s showed, on average, increasing genetic diversity and divergence from the subtype B consensus sequence. These results indicate that the majority of HIV-1 currently circulating in the United States may be descended from an initial introduction and rapid spread during the mid- to late 1970s of subtype B viruses with limited variability (i.e., a founder effect). As expected from the starburst-shaped phylogeny of HIV-1 subtype B, contemporary U.S. strains were, on average, more closely related at the nucleic acid and amino acid levels to the earlier 1978-1979 env variants than to each other. The growing levels of HIV-1 genetic diversity, one of multiple obstacles in designing a protective vaccine, may therefore be mitigated by using epidemic founding variants as antigenic strains for protection against contemporary strains.
authors.affiliation: Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87501, USA.
authors.forename: B
authors.initials: B
authors.lastname: Foley
authors.forename: H
authors.initials: H
authors.lastname: Pan
authors.forename: S
authors.initials: S
authors.lastname: Buchbinder
authors.forename: E L
authors.initials: EL
authors.lastname: Delwart
mesh_terms: D016915:AIDS Vaccines; D001483:Base Sequence; D004279:DNA, Viral; D015195:Drug Design; D014644:Genetic Variation; D015699:HIV Envelope Protein gp120 / Q000235:genetics*; D015658:HIV Infections / Q000097:blood / Q000453:epidemiology* / Q000821:virology; D015497:HIV-1 / Q000145:classification / Q000235:genetics*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics*; D010802:Phylogeny; D012495:San Francisco / Q000453:epidemiology
chemical_list: D016915:AIDS Vaccines; D004279:DNA, Viral; D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments