BIOLOGICALLY SAFE, NON-TRANSMISSIBLE PSEUDORABIES VIRUS VECTOR VACCINE PROTECTS PIGS AGAINST BOTH AUJESZKYS-DISEASE AND CLASSICAL SWINE FEVER

Envelope glycoprotein D (gD) of pseudorabies virus (PRV) is essential for penetration but is not required for cell-to-cell spread. When anim als are inoculated with a phenotypically complemented PRV gD mutant, t he virus is able to spread locally by means of direct cell-to-cell tra nsmission, but progeny virions released by infected cells are non-infe ctious because they lack gD. Therefore, the virus cannot be transmitte d from inoculated animals to other animals. This property makes a PRV gD mutant an attractive candidate as a safe vaccine vector. To examine whether a self-restricted, non-transmissible PRV mutant can be used a s a biologically safe vaccine vector, a gD/gE-negative PRV recombinant virus which expresses envelope glycoprotein E2 of classical swine fev er virus was constructed. Vaccination of pigs showed that the recombin ant virus was able to protect pigs against both Aujeszky's disease and classical swine fever.