SLOWER HETEROSEXUAL SPREAD OF HIV-2 THAN HIV-1

Because of the similar virological properties of HIV types 1 and 2, HI V-2 was assumed to be as infectious and capable of inducing AIDS as HI V-1. Seroepidemiological studies have shown significant rates of HIV-2 infection in West Africa, and surveys from other regions of the world indicate that the spread of HIV-2 infection continues. However the pa thogenic potential of HIV-2 is considered to be lower than that of HIV -1. It is therefore important to understand the transmission propertie s of HIV-2 and its contribution to the AIDS pandemic. Since 1985, we h ave prospectively studied 1452 registered female prostitutes in Dakar, Senegal, with sequential evaluation of their antibody status to HIV-1 and HIV-2. During the study the overall incidence of HIV-1 and HIV-2 was the same (1-11 per 100 person-years of observation [pyo]). However , the annual incidence of HIV-1 increased substantially: there was a 1 .4-fold increased risk per year and thus a 12-fold increase in risk ov er the entire study period. The incidence of HIV-2 remained stable, de spite higher HIV-2 prevalence. In our population the heterosexual spre ad of HIV-2 is significantly slower than that of HIV-1, which strongly suggests differences in the viruses' infectivity potential.