AIDS. 1997 Jan;11(1):81-7. Unique Identifier : AIDSLINE MED/97264207
OBJECTIVES: To determine HIV-1 env and gag subtypes in male homosexual
and heterosexual populations in Cape Town, South Africa. DESIGN: DNA was
isolated from blood originating from 61 patients attending local
clinics. Samples were divided according to presumed mode of
transmission: male homosexual (n = 26), heterosexual/vertical (n = 32),
blood transfusion (n = 1) and unknown (n = 2). METHODS: Proviral HIV-1
DNA was subtyped by heteroduplex mobility assay (HMA) based on the 799
base-pair V3-V5 region of the env gene (n = 47) or by sequence analysis
of the p17 region of the gag gene (n = 33), or both. For HMA, reference
plasmids were constructed containing the V1-V5 env region sequences
(1.2-kb) representative of local subtypes. Subtype designation of
reference subtypes was confirmed by sequence analysis of the V3-loop
region. RESULTS: Analysis of the partial gag sequences and HMA of the
V3-V5 env region identified three subtypes: B, C and D. A fourth env
subtype, subtype E, was also identified by HMA. Subtypes were found to
segregate according to mode of transmission, with subtype B viruses
found in 96% (25 out of 26) of the male homosexual group and subtype C
viruses found in 81% (26 out of 32) of the heterosexual/vertical
transmission group. Subtype B viruses were also found in four
heterosexual patients, one patient infected by blood transfusion and in
two patients with unknown mode of transmission. Subtype D viruses were
found in one male homosexual patient and one heterosexual patient. A
subtype E virus was identified in a heterosexual patient. No discrepancy
was found in subtype designation in samples analysed in both between the
gag and env regions (n = 19). CONCLUSIONS: Subtype B viruses were
associated with male homosexual transmission and subtype C viruses with
heterosexual transmission, suggesting two independent epidemics. This
data may have implications in the selection of appropriate vaccines for
different risk groups in the country.
*HIV Infections/TRANSMISSION *HIV-1/GENETICS