Several prospective studies published over nearly two decades have explored the relationship between vaginal dysbiosis and women’s risk of HIV acquisition. These studies have typically used Gram stain scoring based on bacterial morphotypes to characterize vaginal microbiota in categories including normal (scores 0-3), intermediate vaginal microbiota (scores 4-6), and bacterial vaginosis (BV; scores 7-10). Together, these data suggest that both intermediate vaginal microbiota and BV are associated with about a 1.5-fold increase in women’s risk of HIV infection. Because disruption of the vaginal microbiota is highly prevalent, particularly in populations at substantial risk for HIV infection, these conditions could have a sizable impact on HIV transmission at a population level. Newer approaches that characterize the vaginal microbiota using nucleic acid amplification based techniques have illuminated much greater heterogeneity among women with vaginal dysbiosis than previously appreciated. Studies presented during the past year suggest that vaginal bacterial community characteristics and the presence of specific bacterial taxa may play a key role in mediating women’s risk of HIV infection. Vaginal microbiota could impact susceptibility to HIV through multiple pathways including inflammation, the presence and concentrations of soluble innate and adaptive immune mediators, production of HIV inducing factors, and disruption of structural barriers to HIV infection including vaginal and cervical mucus and epithelium. Interventions aimed at elimination of high-risk bacterial taxa could reduce women’s risk of acquiring HIV.
CROI Conference
