Background:
Women account for over half of people living with HIV (PLH) but they are largely underrepresented in HIV-1 cure studies. Biological sex impacts host immune responses which may lead to sex-specific selection and evolution of HIV reservoir cells. However, sex-specific differences in HIV reservoir landscapes, including proviral reservoir size, composition, and integration site profile among long-term ART-treated (LT-ART) individuals remain unclear.
Methods:
We included a total of 64 participants (34 males and 30 females, all cisgender), who remained on continuous suppressive ART for a median of 20 (range: 15 – 25) consecutive years with no more than 2 recorded plasma viremia blips (< 100 copies/mL). HIV-1 proviruses and chromosomal integration sites were analyzed using FLIP-seq and MIP-seq, as described in our previous work.
Results:
There were no significant differences in the demographic characteristics between female and male participants in the study. In total, n=4012 HIV genomes were detected in the LT-ART cohort (n=1490 in females and n=2522 in males). Frequencies of total and defective HIV-1 genomes were not different between males and females; however, we found a small trend toward higher frequencies of intact proviruses in females (0.69 vs. 0.53 median intact DNA per million PBMC, p = 0.15). Moreover, relative proportions of intact proviruses among total proviruses were higher in females (6.51% vs. 3.65%, p < 0.0001). This difference appeared to be at least partially attributable to a higher frequency of clonally-expanded intact proviruses in females compared to males (3.37 vs. 0.34 median clonal intact DNA per million PBMC, p = 0.0029). Intriguingly, within a total of 246 integration sites (145 intact, 101 defective) identified, we observed higher proportions of intact proviruses integrated in heterochromatin locations (including centromeric/satellite DNA, ZNF genes) and non-genic DNA in females than males (88% vs. 58%, p < 0.0001).
Conclusions:
Taken together, our results suggest a sex-based difference in host immune-driven proviral landscape evolution during long-term suppressive ART. Immune mechanisms responsible for viral reservoir cell selection are unclear at present but may include sex-specific immune responses. The HIV reservoir in women is associated with features of deeper latency; therefore, women may be primed to achieve a state of HIV control, and the inclusion of women in cure studies should be a priority.