Ngandu NK, et al. – Women in the CAPRISA 004 trial assigned to use 1% tenofovir (TFV) microbicide gel, who became HIV–1 infected, had higher viral load set–point and slower antibody avidity maturation compared with placebo participants. This work was planned to assess whether TFV gel was selected for viruses with altered genetic characteristics. As per finding, viruses infecting TFV gel recipients were closer to the consensus sequence of regional strains and had higher transmission index. The transmission index seemed to have a weak correlation with concomitant viral load. Researchers observed that a reduced acquisition risk could have enhanced the barrier to infection, therefore, selecting for fitter, more consensus–like viruses. They suggest considering such virus fitness effects for future pre–exposure prophylaxis and vaccine trials.