Heterogeneous expression of Pil3 pilus is critical for Streptococcus gallolyticus translocation across polarized colonic epithelial monolayers

Link to Pubmed [PMID] – 31837399

Microbes Infect. 2019 Dec;

Streptococcus gallolyticus is an opportunistic pathogen responsible for septicemia and endocarditis. We report that S. gallolyticus UCN34 adheres and crosses epithelial monolayers in a Pil3 dependent manner. Confocal images revealed a paracellular passage. Both the Δpil3 mutant and the Pil3+ overexpressing variant were unable to cross Caco-2 and T84 barriers. However, combining live Δpil3 mutant with fixed Pil3+ variant in a 9:1 ratio allowed efficient translocation of the Δpil3 mutant. These results demonstrate that heterogeneous expression of Pil3 plays a key role for UCN34 translocation across the intestinal barrier. Through this skilful strategy, S. gallolyticus probably evade host immune responses.