A differential ELISA based on recombinant immunodominant epitopes of the gE gene of SHV-1 in a baculovirus-insect cell system to discriminate between pigs infected naturally with pseudorabies and vaccinated pigs

In the present study, the fragment corresponding to the immunodominant epitopes of the gE gene (gEpi) from the CL15 Argentinean strain of pseudorabies virus was expressed successfully in a baculovirus-insect cell system that contained the M6 gene of Bluetongue virus, which encodes the NS1 nonstructural protein. This protein has the ability to polymerize into highly immunogenic tubules inside infected cells that can be purified at large quantities by ultracentrifugation. Previously, the NS1 protein has been expressed by fusing it to sequences derived from viruses, such as human immunodeficiency virus type 1, hepatitis B virus, bovine leukemia virus, foot-and-mouth disease virus and influenza A virus. In the present study, a recombinant protein was obtained containing the gEpi fused to NS1 (NS1-gEpi) and used it as ELISA antigen for detection of anti-gE antibodies in order to discriminate between infected and vaccinated animals. This is the first report where gEpi was expressed in this particular baculovirus-insect cell system.