Immunological evaluation of Escherichia coli expressed E2 protein of Western equine encephalitis virus.

The Western equine encephalitis virus (WEEV) is a potential Biological Warfare (BW) agent. The WEEV is endemic in western Canada and has caused epidemics of "sleeping sickness" with a mortality rate of 7-9%. The E2 glycoprotein is a structural component of the WEEV and elicits production of neutralizing antibodies against the virus following an infection event. The envelope glycoprotein E2 is considered as the major target protein for the development of vaccines because it includes epitopes that elicit neutralizing antibodies. This report describes the successful cloning of the E2 gene of WEEV and expression in Escherichia coli as inclusion bodies. The inclusion bodies were successfully solubilized, refolded and the immunogenicity of this non-glycosylated protein was assessed in BALB/c mice. Recombinant E2 (rE2) protein was specifically and strongly recognized by inactivated WEEV-immunized mice serum sample on ELISA, suggesting that E. coli derived rE2 protein retained at least some functional characteristics of its native conformation. The immunogenicity of the refolded rE2 protein was demonstrated by strong humoral and cell mediated immune (CMI) responses in rE2-immunized BALB/c mice. The current study also demonstrated that rE2-immunized mice could be partially protected from lethal challenge of WEEV.