Shedding of HIV-1 subtype E in semen and cervico-vaginal fluid.

Preliminary evidence suggests that HIV subgroups differ in both their transmissibility and virulence. In Thailand HIV-1 subtype E (accounting for almost 95% of total HIV cases) is transmitted primarily through heterosexual sex with a predominance of female-to-male infection. This study characterized virus shedding patterns in seminal and cervico-vaginal fluids from 30 asymptomatic husband-wife pairs from Bangkok Thailand known to be infected with HIV-1 subtype E. HIV-1 subtype E was detected in 22 (77.3%) cervico-vaginal and 22 (77.3%) seminal fluid samples. HIV-1 subtype B in contrast is found in only 30-50% of cervico-vaginal specimens; detection of subtype B in seminal specimens (70-80%) is comparable to that identified for subtype E in the present study. The isolation rate of HIV-1 was 36.67% from semen and 16.67% from cervico-vaginal secretions. The number of HIV-1 subtype E DNA copies in blood--but not in genital fluids--was inversely correlated with the number of blood CD4+ T cells. The increased shedding of HIV-1 DNA subtype E compared with other subtypes in the female genital tract presumably accounts for the rapid spread of subtype E among heterosexuals in Thailand.