Streptococcus equi chimeric antigen CNE-CPB-EAG (CCE)

The CCE chimeric antigen is a recombinant fusion protein derived from Streptococcus equi subsp. equi, the primary pathogen responsible for strangles, a highly contagious upper respiratory tract infection in horses. This antigen is a synthetic construct that combines three critical surface-exposed virulence factors: the collagen-binding protein (CNE), the C5a peptidase (CPB), and the α2-macroglobulin/albumin-binding protein (EAG) (Guss et al., 2009; Flock et al., 2004). CNE mediates the initial adherence of the bacteria to host tissues, while CPB functions as an immune-evasion factor by cleaving the chemoattractant C5a, thereby preventing the recruitment of polymorphonuclear leukocytes to the site of infection (Lindmark et al., 2001). EAG further contributes to pathogenesis by binding host plasma proteins, such as α2-macroglobulin and albumin, which helps the bacterium evade host immune detection (Lindmark et al., 1999). As a therapeutic target, CCE is primarily utilized in the development of subunit vaccines designed to provide protective immunity without the risks associated with live-attenuated vaccines. When administered, the CCE antigen stimulates the production of specific IgG and IgA antibodies that neutralize the biological activities of CNE, CPB, and EAG (Guss et al., 2009). This antibody-mediated neutralization blocks bacterial colonization, restores the host's ability to recruit immune cells via the complement system, and enhances opsonophagocytosis. While CCE was a foundational construct in vaccine research, its components have been further refined in commercial products like Strangvac to optimize immunogenicity and protection against equine strangles (Intervacc AB, 2021).

Other names

CNE-CPB-EAG fusion proteinStreptococcus equi recombinant antigen CCECCE fusion proteinCollagen-binding protein, C5a peptidase, and EAG fusion

Induction of active immunity through the production of neutralizing antibodies that inhibit bacterial adhesion, complement degradation, and host protein masking.