Use of temperature, trypsin and biological tests for the intraspecies differentiation of local strains of Aujeszky's disease virus
Arnaudov, K.
Veterinarno-Meditsinski Nauki 12(6): 57-61
1975
ISSN/ISBN: 0324-1068 PMID: 179192 Document Number: 86328
Studies were carried out with 8 strains of Aujeszky's disease virus using a temperature test (50 degrees C for 1 hour), a trypsin test (0.5 mg per cu. cm at 37 degrees C 1 hour), and a biologic test. The strains were isolated from the brain of dead pigs that have presumably been affected with encephalitis. They proved sensitive when studied with the temperature and the trypsin tests sharply lowering their titer. The viruses isolated from pneumonic foci in the lungs of pigs in which the disease had assumed a chronic course turned out to be considerably more resistant with the use of the two tests. The vaccinal strain MK was shown to be the most resistant in all tests. Comparable results were obtained also with the study of the viruses employing a modified test with young albino mice weighing 7-8 grams. The cerebral inoculation of the viruses aimed in this case at establishing the intracerebral pathogenetic index (IPI). Test rabbits were also used for the same purpose. The virulent strains had correspondingly a shorter incubation period and in rabbits there was a well pronounced clinical course, the IPI value being higher than 1.50. To latent viruses the rabbits responded with a protracted clinical course, and IPI ranged between 0.20 and 0.95.