THE PRODUCTION OF A TRUNCATED FORM OF BACULOVIRUS-EXPRESSED EHV-1 GLYCOPROTEIN-C AND ITS ROLE IN PROTECTION OF C3H (H-2K(K)) MICE AGAINST VIRUS CHALLENGE

A truncated form of the equine herpesvirus 1 (EHV-1) glycoprotein C (g C) gene was expressed in baculovirus. The gC signal sequence was subst ituted with the honeybee melittin signal sequence and the transmembran e region was replaced with a histidine tag. The recombinant virus prod uced high levels of gC in both the cells and supernatants of infected cells. The protein was present by 24 h and maximal secretion occurred at 96 h post-infection. The recombinant protein was antigenically auth entic as shown by its reaction with each of a panel of individual mono clonal antibodies specific for the five distinct antigenic sites on EH V-1 gC. Recombinant gC was purified from the supernatant of infected c ells by immune-affinity chromatography and used to immunize C3H (H-2K( k) haplotype) mice. This incurred a gC specific antibody response agai nst both the recombinant protein and EHV-1 gC. 'Pepscan' analysis show ed that the gC specific antibodies in serum from these mice reacted wi th the same epitopes on gC as those recognized by antibodies in conval escent equine sera (i.e. antibodies were specific to antigenic sites o ne and five). A third previously unrecognized antibody binding site at the carboxyl terminus was also detected (Antibody binding domain I), A T-cell proliferative response against EHV-l was detected in splenocy te populations taken from vaccinated mice. Further, the recovery of vi rus from the lungs and turbinates following challenge of mice with EHV -I was significantly reduced. These findings indicate that baculovirus expressed gC may contribute significantly to a subunit vaccine prepar ation aimed at protecting horses from EHV-1 infection.