P40.13
Background: A challenge in developing interventions to prevent mucosal HIV transmission is incomplete understanding of correlates of vaginal transmission, including mucosal inflammation. Vaginal SIV/SHIV transmission in pigtail macaques is an excellent model for HIV transmission, however little is known about how genital bacterial species may influence inflammation and SIV transmission.
Methods: Broad-range 16S rRNA gene PCR and pyrosequencing was performed on vaginal swabs for bacterial identification using a cohort of pigtail macaques in a cross-sectional analysis (N=22), and a more limited longitudinal analysis (N=3). Bacteria were identified to the species or genus level using a custom designed reference set of sequences, providing comprehensive characterization compared to previous studies focused on genera and phylum.
Results: Pigtail macaques had diverse microbial communities at all phases of the menstrual cycle, with a range of dominant bacteria in different animals, including Prevotella, Porphyromonas, Dialister, Clostridiales, Bacteroides, Streptococcus and Lactobacillus species. In contrast to previous studies, we found three animals had a Lactobacillus-dominant vaginal microbiota, all at peak sex skin swelling (indicating ovulation). Several species were identified that are commonly found in bacterial vaginosis (BV) in humans, including Atopobium vaginae, Prevotella buccalis, BVAB2, Peptoniphilus lacrimalis, Prevotella timonensis and Gardnerella vaginalis. Longitudinal sampling demonstrated that vaginal bacterial communities were dynamic and possibly driven by alterations in environment throughout the menstrual cycle.
Conclusions: The macaque vaginal microbiota is diverse, dynamic, and can resemble the human vaginal microbiota, including BV-associated bacteria as well as Lactobacillus spp. These data provide a foundation for understanding how vaginal microbial communities may impact risk of HIV/SIV transmission using these models.
