A Novel Conserved Protein in Streptococcus agalactiae, BvaP, Is Important for Vaginal Colonization and Biofilm Formation.

Streptococcus agalactiae (group B streptococcus [GBS]) infections in neonates are often fatal and strongly associated with maternal GBS vaginal colonization. Here, we investigated the role of an uncharacterized protein, BvaP, in GBS vaginal colonization. was previously identified as the most highly upregulated gene in the GBS A909 transcriptome when comparing vaginal colonization to growth in liquid culture. We found that the absence of BvaP affects the ability of GBS to adhere to extracellular matrix components and human vaginal epithelial cells, and the ability of a Δ mutant to colonize the murine vaginal tract was significantly decreased. Cellular morphological alterations such as changes in cell shape, chain length, and clumping were also observed in a knockout mutant strain. Given its high expression level , high degree of conservation among GBS strains, and role in vaginal colonization, BvaP may be an eligible target for GBS vaccination and/or drug therapy. Neonatal GBS disease is a major cause of morbidity and mortality, and maternal vaginal colonization is the leading risk factor for the disease. Colonization prevention would greatly impact the rates of disease transmission, but vaccine development has stalled as capsular polysaccharide vaccines have low immunogenicity While these vaccines are still in development, the addition of a protein conjugate may prove fruitful in increasing immunogenicity and strain coverage across GBS serotypes. Previous research identified as a highly upregulated gene during murine vaginal colonization. This study reveals that Sak_1753 is required to maintain proper GBS cellular morphology and colonization phenotypes and is required for full vaginal colonization in a murine model. We have renamed Sak_1753 group streptococcus aginal dherence rotein (BvaP). The findings of this study indicate that BvaP is important for GBS colonization of the vaginal tract and, given its high expression level and strain conservation, may be a candidate for vaccine development.