# Prevotella are major contributors of sialidases in the human vaginal microbiome

## TL;DR

This study shows that Prevotella bacteria are a major source of sialidase enzymes in the vaginal microbiome, which may contribute to health issues like bacterial vaginosis and preterm birth.

## Contribution

The study identifies and characterizes sialidases from Prevotella, revealing their prevalence and activity in the vaginal microbiome.

## Key findings

- Prevotella sialidase genes and transcripts are more prevalent and abundant than those from Gardnerella in the vaginal microbiome.
- Prevotella sialidases show activity toward human mucin, suggesting a role in degrading protective mucus layers.
- Sialidase gene sequences are conserved across Prevotella clades from different geographic regions.

## Abstract

Sialidase activity in the vaginal microbiome is increased in bacterial vaginosis and strongly associated with other adverse health outcomes. Sialidase enzymes release sialic acid from host-derived glycans in the vaginal environment, altering their structures and functions. However, biochemical studies of vaginal bacterial sialidases have been limited to one genus, Gardnerella. In this work, we identify and characterize multiple sialidase enzymes in vaginal bacteria of the genus Prevotella, including an enzyme active toward human mucin. We find that genes and transcripts encoding Prevotella sialidases are more prevalent and abundant in vaginal microbial communities than those from Gardnerella. Our work highlights Prevotella bacteria as an underappreciated source of sialidase transcripts in metatranscriptomes with important implications for our understanding of sialidase producers in the vaginal ecosystem.

Elevated bacterial sialidase activity in the female genital tract is strongly associated with poor health outcomes including preterm birth and bacterial vaginosis (BV). These negative effects may arise from sialidase-mediated degradation of the protective mucus layer in the cervicovaginal environment. Prior biochemical studies of vaginal bacterial sialidases have focused solely on the BV-associated organism Gardnerella vaginalis. Despite their implications for sexual and reproductive health, sialidases from other vaginal bacteria have not been characterized. Here, we show that vaginal Prevotella species produce sialidases that possess variable activity toward mucin substrates. The sequences of sialidase genes and their presence are largely conserved across clades of Prevotella from different geographies, hinting at their importance globally. Finally, we find that Prevotella sialidase genes and transcripts, including those encoding mucin-degrading sialidases from Prevotella timonensis, are highly prevalent and abundant in human vaginal genomes and transcriptomes. Together, our results identify Prevotella as a critical source of sialidases in the vaginal microbiome, improving our understanding of this detrimental bacterial activity.