J8 epitope of the Group A Streptococcus M protein (J8)

The J8 epitope is a 28-amino acid chimeric peptide derived from the highly conserved C-repeat region of the M protein of Group A Streptococcus (Streptococcus pyogenes) (Batzloff et al., 2004). The M protein is a primary virulence factor that allows the bacteria to evade the host immune system by inhibiting opsonization and phagocytosis (Fischetti, 1989). While the N-terminal region of the M protein is hypervariable, the C-terminal region is conserved across nearly all GAS strains, making the J8 epitope a candidate for a universal vaccine (Pandey et al., 2015). The J8 peptide is engineered to maintain an alpha-helical conformation, which is critical for the induction of protective antibodies. It is typically conjugated to a carrier protein, such as diphtheria toxoid (J8-DT), to enhance its immunogenicity in clinical applications (Ghaffar et al., 2021). Vaccination with J8-DT aims to elicit protective IgG antibodies that facilitate the opsonophagocytic killing of the bacteria. This approach is designed to prevent a wide range of GAS-related conditions, including pharyngitis, impetigo, and invasive diseases. Furthermore, targeting the conserved region helps avoid the risk of inducing autoimmune responses associated with other parts of the M protein, which can lead to rheumatic heart disease (Good et al., 2013).

Other names

J8 peptideJ8-DTM protein C-repeat region epitopeStreptococcus pyogenes M protein J8 fragmentConserved C-terminal M protein epitope

Induction of opsonizing IgG antibodies that target the conserved C-terminal region of the M protein to facilitate phagocytic clearance of Streptococcus pyogenes.