[Production of a vaccine against pseudoplague in poultry using the La Sota strain]

Comparative investigations were carried out on the quality and quantity of a vaccine against Newcastle disease in birds with the La Sota strain, obtained after the routinely applied productional technology or after some of the author's modifications of the method. The addition of penicillin, kanamycin, oleandomycin or chlorocid to the virus intended for an archive showed on unfavourable effect on the development of the chick embryos used; there was no such effect on the La Sota strain multiplying in them either. The industrial production of this vaccine with the addition of the above entibiotics used either alone or in combination had favourably influenced the sterility of the virus suspension. Data showed that at to and fro moving of the embryos following infection with the virus every two hours at an angle of 150 degrees C the number of dead embryos at the 76th hour was lower. The agglutination-reaction titer was considerably higher. A proof of high immunogenicity of the vaccines obtained was also the infectious titer of the virus in 11-old chick embryos--log 10(-9), on an average. On the 11th day of incubation the embryos infected with the La Sota strain of the virus had greater amounts of alanto-amnionic fluid than those kept in the incubator and infected on the 10th day. At infecting on the 11th day of age greater amounts of virus suspension were obtained without lowering of its infectious titer; thus, its immunogenic properties remained unchanged.