Infectious Diseases in Obstetrics and Gynecology However, the association between Gardnerella vaginalis and the presence of more nucleated cells in the vagina suggests that the BV-associated bioﬁlm, of which G. vaginalis is a signiﬁcant component, may cause direct eﬀects on the epithelial surface and may be a mechanism to facilitate entry or shedding of HIV. It is not surprising that the absence of L. crispatus is associated with higher vaginal pH, but the signiﬁcant eﬀect of the BVABs on vaginal pH is a new ﬁnding. Given the strongly signiﬁcant P values for this ﬁnding in spite of the small sample size, it is likely that this is a true biologic phenomenon that may be related to fermentation products produced by these fastidious bacteria as well as G. vaginalis, Megasphaera, Leptotrichia, and Sneathia spp [22]. Lower pH has been shown to inactivate HIV-1 [23]; thus any organism that increases the normally low vaginal pH may facilitate replication and proliferation of HIV-1. We did not see a relationship between quantities of any individual bacteria and vaginal shedding of HIV, which is in contrast to a previous study that looked at the relationship between concentrations of Lactobacillus species, Gardnerella vaginalis, and Mycoplasma hominis [10]. That study had signiﬁcantly more women, all of whom had a log higher detectable plasma viral load than the women in our study and none of whom were on highly active ART, thus making it signiﬁcantly more likely that they would have detectable vaginal HIV shedding and power to detect associations. As our understanding of the bacterial diversity of BV grows, it seems less likely that one individual bacterium will be associated with all adverse outcomes in all women. Rather, we suspect that the loss of protective lactobacilli with a resulting rise in pH and production of multiple fermentation products by anaerobes work together to produce negative eﬀects such as increased shedding of HIV-1 [24]. There are several limitations to this study. The small study population and heterogeneity of bacterial communities in individual women result in limited power to detect relationships between individual bacteria and HIV shedding. Although individual samples were selected randomly, not all samples were available and thus this analysis does not represent a true random sampling of the parent cohort. The lack of an HIV-1-uninfected control group means that these results may not be generalizable to women without HIV infection. However, the prevalence and quantities of bacteria described in this population are similar to those reported in an HIV-1 negative population, as is the heterogeneity between individuals [8]. One diﬀerence in this cohort is that the prevalence and concentration of Lactobacillus crispatus was the same between women with and without BV. This may be an artifact of sample selection but suggests that this cohort may have unique features. Additionally, BV was diagnosed by clinical criteria, while Gram-stain criteria are frequently used as a gold standard in research. In this type of analysis we feel that the clinical diagnostic criteria are quite relevant. Since the Gram stain criteria give a higher score to women with more G. vaginalis morphotypes [25], it would not be surprising to ﬁnd that women with BV diagnosed by Gram stain have higher concentrations of G. vaginalis using PCR. Thus, comparing bacterial qPCR results to clinical criteria 5 is a more independent comparison. The contribution of other genital tract infections to these results is diﬃcult to assess. Coinfection with gonorrhea, Chlamydia, or syphilis was previously seen to be very low in this cohort [18] but was not measured at each visit. The use of wet mount to diagnose yeast or Trichomoniasis has low sensitivity [26, 27] and may have misdiagnosed some women. Several bacteria found in HIV-1-infected women with BV may impact HIV shedding through their impact on promoting turnover of nucleated vaginal epithelial cells (Gardnerella vaginalis) or by increasing vaginal pH (BVAB2). There was a trend suggesting that BVAB1, BVAB2, and BVAB3 may be associated with increased shedding of HIV- 1, but this hypothesis will need to be conﬁrmed or refuted in larger studies. Acknowledgments This research was supported by NIH/NIAID RO1 AI40350 (SCU), K24AI066884 (SCU), Centers for AIDS Research at Lifespan/Brown/Tufts Center (P30AI42853) (SCU), and Emory University (P30AI050409) (AC) and R01AI061628 (DF). Dr. Mitchell is supported by the NICHD Women’s Reproductive Health Research Career Development Award (K12-HD001264). References [1] D. A. Eschenbach, S. Hillier, C. Critchlow, C. Stevens, T. DeRouen, and K. K. 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