Streptococcus mutans surface protein antigen (SpaP)

Streptococcus mutans surface protein antigen (SpaP), also known as Antigen I/II, is a 185-kDa cell surface adhesin and a primary virulence factor of the cariogenic bacterium Streptococcus mutans. It mediates the initial, sucrose-independent attachment of the bacteria to the acquired salivary pellicle on tooth surfaces by specifically binding to the host scavenger receptor glycoprotein GP340, also known as Deleted in Malignant Brain Tumors 1 (DMBT1). This interaction is a critical first step in the formation of dental plaque and the subsequent development of dental caries. Beyond its role in the oral cavity, SpaP has been implicated in the pathogenesis of infective endocarditis, as it facilitates bacterial adherence to damaged heart valves and vascular endothelium. Due to its central role in colonization, SpaP is a major target for the development of dental vaccines, monoclonal antibodies like Guy's 13, and anti-adhesive peptides such as p1025. However, a significant challenge in targeting SpaP is the potential for immunological cross-reactivity with human proteins, which necessitates careful design of therapeutic agents to avoid autoimmune responses.

Other names

Antigen I/IIAg I/IIPAcP1Antigen BSRIFMSL-1Surface protein A

Inhibition of bacterial adhesion to the salivary pellicle by blocking the interaction between SpaP and salivary agglutinin (gp340/DMBT1)