Role of Phosphorylcholine in Streptococcus Pyogenes Adherence to Epithelial Cells

Abstract Background: This study aimed to evaluate the influence of Phosphorylcholine (PC) expression on the adherence and invasion of Streptococcus pyogenes (S. pyogenes) to epithelial cells to clarify the potential effectiveness of a vaccine targeting PC. Methods: Eight clinical strains of S. pyogenes were cultured overnight, and PC expression was evaluated by fluorescence-activated cell sorting. Bacterial adherence and invasion were examined using Detroit 562 cells. An anti-PC-specific monoclonal antibody (TEPC-15) was used to inhibit bacterial PC, and a platelet-activating factor receptor (PAF-R) antagonist (ABT-491) was used to inhibit cellular PAF-R. Additionally, amplification of the emm gene was performed using polymerase chain reaction with the standard primers. Results: The level of PC expressed on the S. pyogenes surfaces differed in each strain. Furthermore, PC expression was different even in the same emm type. Adherence assay experiments showed that there was a significant negative correlation between TEPC-15 and ABT-491 inhibitory effects and PC expression in S. pyogenes. Similarly, intracellular invasion assay experiments showed that there was a significant negative correlation between TEPC-15 and ABT-491 inhibitory effects and PC expression in S. pyogenes. Conclusion: The present study suggests that PC is involved in the cell adhesion and invasion of S. pyogenes, regardless of the emm type.