The vaginal Torquetenovirus titer varies with vaginal microbiota composition in pregnant women

Torquetenovirus (TTV) is a nonpathogenic endogenous virus whose abundance varies with the extent of immune system activation. We determined if the TTV titer in the vagina of pregnant women was associated with vaginal microbiota composition and levels of compounds in vaginal secretions. Vaginal TTV and microbiota composition in 494 second trimester pregnant women were identified by gene amplification and analysis. Vaginal matrix metalloproteinases (MMPs), tissue inhibitors of MMP (TIMP) and lactic acid isomers were measured by ELISA. Dominance was defined as the relative abundance of a specific bacterium or species at >50% of the total number of bacteria identified. Clinical data were obtained by chart review. The median log(10) TTV titer was lowest when Lactobacillus species other than L. iners were dominant (<1.0) as compared to when L. iners (4.1, p = 0.0001), bacteria other than lactobacilli (4.5, p = 0.0016) or no bacterium (4.7, p = 0.0009) dominated. The TTV titer was inversely proportional to L. crispatus abundance (p<0.0001) and directly proportional to levels of G. vaginalis (p = 0.0008) and L. iners (p = 0.0010). The TTV titer was proportional to TIMP-1, TIMP-2, MMP-8 and MMP-9 abundance (p≤0.0002) and inversely proportional to the level of D-lactic acid (p = 0.0024). We conclude that the association between variations in the TTV titer and the relative abundance of specific bacterial species and vaginal compounds indicates that local changes in immune status likely influence vaginal fluid composition.