Group A streptococcal carbohydrate (GAC) (GAC)

Group A streptococcal carbohydrate (GAC) is the defining cell wall antigen of Streptococcus pyogenes, a major human pathogen responsible for a wide spectrum of diseases. The molecule consists of a poly-L-rhamnose backbone with N-acetylglucosamine (GlcNAc) side chains, which are essential for the structural integrity and virulence of the bacterium (Source: van Sorge et al., 2014, Cell Host & Microbe). In the context of vaccine development, GAC is formulated as a glycoconjugate by linking it to a carrier protein to induce a robust, T-cell dependent immune response (Source: Sabharwal et al., 2006, Vaccine). This target is highly conserved across nearly all Group A Streptococcus (GAS) strains, making it a superior candidate for a universal vaccine compared to the highly variable M protein (Source: Frost et al., 2023, NPJ Vaccines). The primary mechanism of action for GAC-based vaccines is the generation of opsonophagocytic antibodies that facilitate the clearance of the bacteria by the host's immune system (Source: Kastenmüller et al., 2021, Frontiers in Immunology). While GAC is a promising target, researchers must carefully evaluate the potential for cross-reactivity between the GlcNAc moiety and human tissues to ensure safety against post-streptococcal autoimmune diseases (Source: Shikhman et al., 1994, Journal of Immunology).

Other names

Group A carbohydrateLancefield Group A antigenStreptococcus pyogenes cell wall carbohydratePoly-rhamnose GlcNAc polysaccharideGAC glycoconjugate

Induction of protective opsonophagocytic IgG antibodies that recognize the carbohydrate epitope on the bacterial surface, leading to complement activation and phagocytosis.