ANALYSIS OF THE EQUALIZATION OF INVERTED REPEATS AND NEUROVIRULENCE USING A PSEUDORABIES VIRUS MUTANT STRAIN ALTERED AT THE UL IR JUNCTION/

A recombinant pseudorabies (Aujeszky's disease) virus (PrV) designated as vE16lac was constructed by deleting a 3-kbp DNA segment spanning t he junction of long and short components of the viral genome, and by r eplacing the deleted segment with a lacZ-expression cassette. The aim of constructing this mutant was (a) to determine whether the terminal repeat (Tr) can serve as a template for the regeneration of the intern al repeat (Ir), and (b) whether this deletion causes a reduction in th e neuroinvasiveness of the virus. To analyze the mechanism of equaliza tion, revertant viruses were selected and structurally characterized f rom vE16lac infection of PK-15 cells, mice and pigs. Because all rever tants acquired Ir sequences identical to that of the wild-type virus, the equalization process occurred using the Tr as a template to recons titute the Ir. We also found that the recombinant virus vE16lac was Vi rulent in both pigs and mice. The data are discussed in view of studie s performed with similar PrV mutants by other authors (Rall et al., 19 92, Dean and Cheung, 1995 and Dean et al., 1996).