Eq85 chimeric antigen (Eq85)

Eq85 is a recombinant chimeric antigen and a primary component of the Strangvac vaccine, designed to protect horses against strangles, a severe and highly contagious respiratory infection caused by Streptococcus equi subsp. equi (Robinson et al., 2020, Vaccine). This fusion protein is composed of three distinct bacterial virulence factors: EAG (an IgG and albumin-binding protein), ScpC (a C5a peptidase), and SclG (a collagen-like protein) (Guss et al., 2012, PLoS ONE). EAG functions by binding host immunoglobulins and albumin to mask the pathogen from the host immune system, while ScpC degrades the chemoattractant C5a to inhibit neutrophil recruitment to the site of infection. SclG is a surface-exposed protein that contributes to the structural integrity or adhesive properties of the bacterium. By incorporating these elements into a single chimeric molecule, the vaccine elicits a robust immune response, producing antibodies that neutralize these essential survival mechanisms of S. equi (Intervacc AB, 2021). This targeted approach aims to prevent bacterial colonization and reduce the clinical severity of the disease in equine populations.

Other names

Eq85 fusion proteinStreptococcus equi Eq85 antigenEAG-ScpC-SclG fusion proteinAntigen 1 (Strangvac)

Induction of specific neutralizing antibodies (IgG and mucosal IgA) that target and inhibit the functional domains of EAG, ScpC, and SclG, thereby preventing bacterial immune evasion and colonization.