degrades the vaginal epithelial glycocalyx through high fucosidase and sialidase activities.

UNLABELLED

Bacterial vaginosis (BV) is a polymicrobial infection of the female reproductive tract. BV is characterized by replacement of health-associated species by diverse anerobic bacteria, including the well-known and are anerobes that are found in a significant number of BV patients, but their contributions to the disease process remain to be determined. Defining characteristics of anerobic overgrowth in BV are adherence to the mucosal surface and the increased activity of mucin-degrading enzymes such as sialidases in vaginal secretions. We demonstrate that but not strongly adheres to vaginal and endocervical cells to a similar level as but did not elicit a comparable proinflammatory epithelial response. The genome uniquely encodes a large set of mucus-degrading enzymes, including four putative fucosidases and two putative sialidases, PtNanH1 and PtNanH2. Enzyme assays demonstrated that fucosidase and sialidase activities in cell-bound and secreted fractions were significantly higher than for other vaginal anerobes. In infection assays, efficiently removed fucose and α2,3- and α2,6-linked sialic acid moieties from the epithelial glycocalyx. Recombinantly expressed NanH1 and NanH2 cleaved α2,3 and α2,6-linked sialic acids from the epithelial surface, and sialic acid removal by could be blocked using inhibitors. This study demonstrates that has distinct virulence-related properties that include initial adhesion and a high capacity for mucin degradation at the vaginal epithelial mucosal surface. Our results underline the importance of understanding the role of different anerobic bacteria in BV.

IMPORTANCE

Bacterial vaginosis (BV) is a common vaginal infection that affects a significant proportion of women and is associated with reduced fertility and increased risk of secondary infections. is the most well-known BV-associated bacterium, but species including and may also play an important role. We showed that, similar to , adhered well to the vaginal epithelium, suggesting that both bacteria could be important in the first stage of infection. Compared to the other bacteria, was unique in efficiently removing the protective mucin sugars that cover the vaginal epithelium. These results underscore that vaginal bacteria play different roles in the initiation and development of BV.