Diagnostic compatibility of a thymidine kinase, inverted repeat, gI, and gpX modified live gene-deleted PRV vaccine with three differential ELISAs

Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames 50011. The differential pseudorabies virus (PRV) vaccines currently in use in the USA have deletions of the genes coding for the glycoprotein I (gI) and/or glycoprotein X (gpX). The absence of gI and/or gpX allow for the serologic differentiation of vaccinated swine from PRV-infected swine using differential enzyme-linked immunosorbent assays (ELISAs). A newly developed pseudorabies vaccine virus has 4 deletions of the viral genome: the genes coding for gI, gpX, and thymidine kinase and a portion of the repeat region to attenuate the virus. The purpose of this work was to evaluate the diagnostic compatibility of the gI/gpX gene-deleted vaccine with 3 differential vaccines and 3 differential ELISAs currently in use. Pigs vaccinated 3 times with the gI/gpX gene-deleted vaccine remained seronegative on the 3 differential ELISAs tested. Pigs previously vaccinated with either a gI or gpX gene-deleted vaccine and then vaccinated with the gI/gpX gene-deleted vaccine remained seronegative on the respective gI or gpX differential assay.