Jori Symons

The speakers in this session examined the events that occur very early after transmission in order to identify factors that can overcome the barrier to ending the spread of HIV infection. This session focused on what influences transmission, how the reservoir is seeded, and how the transmitted virus remains dominant.

HIV infection in women is high, and Dabee demonstrated that the microbiome in the reproductive tract of women correlate with risk of transmission. Replacement of Lactobacillus with Prevotella bivia, resulting in bacterial vaginosis, increases the risk of transmission and recruits CD4 target cells to the vaginal mucosa. In most transmission events, a single virus is transmitted. Carlson showed that this founder virus resembles the consensus sequence whereas with increased exposures, there is transmission of multiple viral species. Ndung’u showed that individuals treated very early after transmission had a lower frequency of HIV-specific CD8 T-cells but these cells had increased ability to produce IFN-γ and persisted over time. However, the reservoir is very rapidly seeded. By using a phylogenetic clock tool, Brumme showed that viruses that are archived prior to ART can be found twenty years later, suggesting that the reservoir potentially contains all viral species that occurred during disease progression.

This session highlighted the importance of studying early infection, which could elucidate new pathways of fighting transmission. Preventing bacterial vaginosis might prove essential in reducing infection rate in women. It will be very interesting to see if the differences in immune response observed in very early treated individuals correlate with time to rebound in treatment interruption studies accompanied with other interventions, such as bNAbs. If treatment interruption studies occur, it would be of interest to see how close the rebounding virus is to the founder virus, and gain further information about the diversity and decay of the viral reservoir.