Study documents initial differences in sexual transmission of HIV between males and females

A genetic analysis of viral RNA from 10 heterosexual couples, in which one partner has sexually transmitted HIV to the other, provides the first documentation of some differences in how the virus infects males and females. According to the Hopkins researchers who led the study, this initial research is essential to understanding why these differences occur and for future development of a vaccine or other preventive methods that could stop sexual transmission of HIV-1.

The couples in the study come from the Rakai Cohort, a Uganda-based population in a long-term study of HIV infection. The researchers tested each couple’s viral RNA to determine which variants, or kinds of HIV-1 strain, were present in each man and woman. Variants of HIV-1 can be distinguished by differences in the gene (gp160) for their protein envelope. The findings showed that only a subset of HIV-1 variants in the initially infected partner was transmitted to the newly infected partner, and the predominant variant in males was not the kind that infected their female partners. And, women infected by men had a greater number of variants than men infected by women.

The selection of HIV-1 during sexual transmission: differences in gp160 diversity in male-to-female versus female-to-male transmission. Oliver Laeyendecker, Jordyn Gamiel, James Shepard, Xianbin Li, David Serwadda, Nelson Sewankambo, Fred Wabwire-Mangen, Francine McCutchan, Jonathan Toma, Wei Huang, Ronald Gray, Maria Wawer, and Thomas Quinn