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NLM AIDSLINE
HIV-1 Clade B: transition to a predominatly heterosexual epidemic.
Bartholomew C; University of the West Indies, Trinidad.
November 30, 1996
3rd Conf Retro and Opportun Infect. 1996 Jan 28-Feb 1;:176. Unique

The initial epidemic of HIV-1 came to Trinidad via sexual contact with North American homosexual men (JAMA 257:2704, 1987) and during 1983/84, all the cases of AIDS in Trinidad were exclusively in male homosexuals/bisexuals. However, there was a rapid transition to a heterosexual epidemic over the ensuing decade, initially via a bisexual bridge (in a culture where IV drug use is absent). Studies initiated in 1987 monitoring HIV-1 prevalence and risk factors in the major STD clinic in Trinidad have Documented a dramatic 4 fold rise in prevalence from 3% in 1987/88 to 13.6% in 1990/91 due to heterosexual transmission with coincident STDs, amplified by increased crack cocaine usage (AIDS 9:389, 1995). Our current prospective studies employing p 24 antigenemia screening have identified 25 acute seroconverters, all heterosexual, over a 24 month period. PCR sequencing of the V3 loop from multiple isolates shows that the virus transmitted in these individuals, as well as in HIV-1 seropositives studied earlier, is a Clade B virus with a sequence similar to the North American/European consensus sequence, differing in the V3 loop by a signature deletion of a threonine amino acid. Recent studies of viral trophism in vitro have suggested that viral growth in specific dendritic cell cultures may correlate with mode and rapidity of spread. For example, Clade E viruses in Northern Thailand associated with heterosexual spread have different culture trophism from Clade B viruses derived from intravenous drug users in Bangkok. In Trinidad a Clade B HIV-1 virus, which has molecular features of a quasi-species, is spreading at a measured incidence as high as 11% per annum in high-risk heterosexuals, indicating that, apart from parenteral and homosexual transmission, a Clade B virus can be transmitted at high levels via the heterosexual route. In vitro studies are to be pursued to determine whether this strain has developed growth characteristics more similar to the Thai Clade E virus.

Bisexuality Consensus Sequence HIV Infections/EPIDEMIOLOGY/*TRANSMISSION HIV-1/*GENETICS Homosexuality, Male Human Male Prevalence Prospective Studies Risk Factors *Sex Behavior Trinidad and Tobago/EPIDEMIOLOGY ABSTRACT

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