[Studies on canine distemper virus. I. Virus cultivation in cell cultures]

Abstract

The author studied the multiplication capacity of 2 avianized strains of canine distemper virus - Onderstepoort and Lederle Encephalitis and 2 country strains - WS-66 and LL-68 in primary cell cultures of chicken embryo fibroblasts and the dog's kidney. The strain Onderstepoort multiplied and caused cytopathological changes in the cell culture of chicken embryo fibroblasts after passaging from villousallantoic membranes of chicken embryos. Maximum titer was found between the 5th and 15th passage in the cell culture and amounted to about 10(5.0) TCID50 or about 10(5.5) EID50. In all 50 passages were carried out. However, multiplication occurred, and cytopathological changes in cell culture of chicken embryo fibroblasts were caused by the strain Lederle Encephalitis only due to the application of initial adsorption and maximum inoculum by 8 successive passages. Maximum TCID50 titre occurred after 40 passages and was about 10(4.5). Both strains preserved their ability to evoke changes on villonsallantoic membranes. Studies on the effect of the inoculum size and incubation time on the virus harvest were carried out Lederle Encephalitis strain on the level of 18-20 passages. In the culture of fibroblasts the most favourable results were obtained by using 10(2.0)-10(2.5) TCID50 inoculum per 10(5.0) cells, harvested after about 96 hr of incubation. Attempts to adapt the strains Onderstepoort and Lederle Encephalitis to cell culture of the dog's kidney gave negative results. Multiplication of the country strains of canine distemper WS-66 and LL-68 was not obtained in the cell culture of the dog's kidney and in that of chicken embryo fibroblasts in the experiment conditions.