Streptococcal protective antigen (Spa) (Spa)

Streptococcal protective antigen (Spa) is a cell-surface protein of Streptococcus pyogenes (Group A Streptococcus) that serves as a significant virulence factor and a promising vaccine candidate (Dale et al., 1996, J. Clin. Invest.). Structurally, Spa is an alpha-helical coiled-coil protein that shares some similarities with the M protein but is immunologically distinct (UniProt P0C0J1). Its primary biological function involves facilitating bacterial adherence to host cells and contributing to the evasion of the host immune response (Dale, 1999, Infect. Dis. Clin. North Am.). In the context of disease, Spa is involved in the pathogenesis of various Group A Streptococcal infections, ranging from mild pharyngitis to severe invasive diseases like toxic shock syndrome and necrotizing fasciitis (Courtney et al., 2006, J. Infect. Dis.). As a therapeutic target, Spa is utilized in the development of recombinant vaccines designed to elicit opsonic antibodies that promote the phagocytosis and clearance of the bacteria (Dale et al., 1996). Unlike some M proteins, Spa is favored in vaccine research because it lacks the specific epitopes known to trigger autoimmune responses such as rheumatic fever (Dale, 1999).

Other names

SpaGroup A streptococcal protective antigenSurface protein SpaStreptococcal surface protein SpaSpa protein

Induction of protective opsonic antibodies that facilitate phagocytic killing of Group A streptococci by host immune cells.