A recombinant fusion protein consisting of West Nile virus envelope domain III fused in-frame with equine CD40 ligand induces antiviral immune responses in horses

Abstract West Nile Virus (WNV) is endemic in the US and causes severe neurologic disease in horses since its introduction in 1999. There is no effective pharmaceutical treatment for WNV infection rendering vaccination as the only approach to prevention and control of disease. The purpose of this study was to evaluate a recombinant vaccine containing domain III (DIII) of the WNV envelope glycoprotein with and without a natural adjuvant equine (CD40L) in producing virus neutralizing antibodies in horses. Serum IgG1 concentration in the groups of horses vaccinated with the DIII-CD40L + TiterMax and DIII-CD40L proteins were significantly increased (p  +  T cells, but not CD4 +  T cells in equine PMBCs. The results demonstrated that vaccination with recombinant WNV E DIII-CD40L protein induced superior humoral and cellular immune response in healthy horses that may be protective against WNV-associated disease in infected animals. CD40L could be utilized as a non-toxic, alternative adjuvant to boost the immunogenicity of subunit vaccines in horses.