Gender differences in HIV-1 diversity at time of infection

To develop an HIV-1 vaccine with global efficacy, it is important to identi fy and characterize the viruses that are transmitted, particularly to indiv iduals living in areas of high incidence. Several studies have shown that v irus from the blood of acutely infected adults was homogeneous, even when t he virus population in the index case was genetically diverse(1-4). In cont rast to those results with mainly male cohorts in America and Europe, in se veral cases a heterogeneous virus population has been found early in infect ion in women in Africa(5,6). Thus, we more closely compared the diversity o f transmitted HIV-1 in men and women who became infected through heterosexu al contact. We found that women from Kenya were often infected by multiple virus variants, whereas men from Kenya were not. Moreover, a heterogeneous virus was present in the women before their seroconversion, and in each wom an it was derived from a single index case, indicating that diversity was m ost likely to be the result of transmission of multiple variants. Our data indicate that there are important differences in the transmitted virus popu lations in women and men, even when cohorts from the same geographic region who are infected with the same subtypes of HIV-1 are compared.