Diverse vaginal microbiome was associated with pro-inflammatory vaginal milieu among pregnant women in Uganda

Vaginal microbiota has been postulated as a key contributor to the disproportionately higher HIV acquisition risk in women. The commensal bacterial communities in the vaginal tract have been implicated in HIV pathogenesis, with strict anaerobes such as Gardnerella and Prevotella causing inflammation and increased frequency of HIV target cells. Young African women are up to six times more likely to be infected with HIV than their male counterparts. The underlying biological mechanisms for increased susceptibility to HIV infection are not fully known, particularly among pregnant women who are also at risk of transmitting the infection to their unborn babies.

We characterized the vaginal microbiome of pregnant women receiving antenatal care. Using 16S rRNA sequencing, we analyzed the richness and abundances of the commensal bacterial communities within the female genital tract. Data was analyzed using qiime2 version 2018, Dada2 plugin, and Naive-Bayes classifier for Taxonomic assignment.

We report that 19% (35/179) of pregnant women had a Lactobacillus-dominant vaginal microbiota profile. Our findings show that the main cervicotypes (“CTs”) were CT1 which was predominantly non-iners Lactobacillus (6%, 11/179), CT2 which was dominated by L. iners (13%, 24/179), CT3 that was Gardnerella dominant (49%, 87/179) and CT4, a mixed CT co-dominated by L. iners, Gardnerella and Atopobium. Cervical lavage of women with non-Lactobacillus CT had significantly higher levels of inflammatory cytokines IL-1beta, TNF-alpha, and chemokines IL-6 and IL-8.

Highly diverse cervicotype (CT4) was associated with inflammation, a known catalyst of HIV acquisition and transmission, within pregnant women regardless of HIV sero-status.