Protection of mice and swine from pseudorabies virus conferred by vaccinia virus-based recombinants.

Glycoproteins gp50, gII, and gIII of pseudorabies virus (PRV) were expressed either individually or in combination by vaccinia virus recombinants. In vitro analysis by immunoprecipitation and immunofluorescence demonstrated the expression of a gII protein of approximately 120 kDa that was proteolytically processed to the gIIb (67- to 74-kDa) and gIIc (58-kDa) mature protein species similar to those observed in PRV-infected cells. Additionally, the proper expression of the 90-kDa gIII and 50-kDa gp50 was observed. All three of these PRV-derived glycoproteins were detectable on the surface of vaccinia virus-PRV recombinant-infected cells. In vivo, mice were protected against a virulent PRV challenge after immunization with the PRV glycoprotein-expressing vaccinia virus recombinants. The coexpression of gII and gIII by a single vaccinia virus recombinant resulted in a significantly reduced vaccination dose required to protect mice against PRV challenge. Inoculation of piglets with the various vaccinia virus-PRV glycoprotein recombinants also resulted in protection against virulent PRV challenge as measured by weight gain. The simultaneous expression of gII and gp50 in swine resulted in a significantly enhanced level of protection as evaluated by weight evolution following challenge with live PRV.