Recovery of Aujeszky's disease virus recombinants from experimentally co-infected swine.

Tissue homogenates were obtained from swine experimentally co-infected with two vaccine strains of Aujeszky's disease virus (ADV). Viral isolates were derived by serial plaque purification directly from tissue homogenates, without an intervening step of isolation and amplification on cell cultures. Use of limiting dilutions and recovery of virus isolates as individual plaques minimized the likelihood of in vitro recombination serving as a confounding source of recombinant ADV. The tyhmidine kinase and glycoprotein X gene sequences were classified as wildtype or deleted, using a battery of polymerase chain reaction assays. On the basis of pairwise combinations of the allelic forms of the thymidine kinase and glycoprotein X genes, the isolates were characterized as recombinant and parental genotypes. The results substantiate the observation that ADV vaccine strains can form genetic recombinants in vivo after experimentally induced co-infection. A full description of this study is available (Am. J. Vet. Res. 54 (4) 540-545, 1993).