RESUMO
Four strains of Aujeszky's Disease virus (ADV) were included in this study; three Mexican field isolates (215,145 nad C-8) in conjunction with the shope reference strain of ADV, which has known pathogeic characteristics. All four strains were included in each treatment, which consisted of heat treatment, trypsin treatment and passed ten times on chicken embryo fibroblasts. Both virus titer and plaque size were determined on the first and tenth passage and on treated and untreated strains. On each of the treatments, the plaque size had significant differences (p=0.001) which had relation to the two factors studied, namely strains and passage level. There was no significant variation related to the type of treatment between strains. With the strains under study, the authors also made rabbit pathogenicity tests, and it was found that on passage one, the strains caused clear nerovus symptoms and death, while on the tenth passage elvel, the Mexican strains produced slight pruritus, few nervous symptoms and allowed the rabbits to survive. The mouse test revealed an increased median death time after the treatments, as well as a large increase in standard deviations. These data are interpreted as an increased heterogeneity of the strains in all of the treatments to the strains of viruses
