COMPARATIVE STUDIES THE BIOLOGICAL PROPERTIES OF EPIZOOTIC VELOGENIC AND MESOGENIC STRAINS OF NEWCASTLE DISEASE VIRUS ISOLATED IN UKRAINE
Newcastle disease - is one of the most dangerous viral diseases of farm and wild birds in the world. It is widely distributed in most countries with a developed poultry. Purpose. To study and compare the biological properties of two Newcastle disease virus that are isolated from chickens in different regions and in different years. Materials and methods. We used Newcastle disease virus strains NDV/hens/Ivano-Frankovsk/58/2007 and LG-85 in studies. Pathological agent was propagated in 9-11 daily SPF chicken embryos. Pathogenicity of viruses was determined by the intracerebral pathogenicity index, the average time of death of chicken embryos infected with minimum lethal dose by conventional methods of OIE [4]. Adult chickens were infected intranasally and intramuscularly at a dose of 0.2 ml extraembryon liquid free from bacterial and fungal contamination in a dilution of 1:10. Results. It was established that infectious titer of NDV/hens/Ivano-Frankovsk/58/2007 virus ranged from 7 lg EID50/0.2 ml to 7,78 lg EID50/0.2 ml. The virus has caused the death of embryos, titer of biological activity for mortality for CE was 8,0 lg ELD50/0.2 ml. For virus NDV/hens/Ivano-Frankovsk/58/2007 average time of CE death was 60 hours. Intracerebral pathogenicity index was 1.61. When intranasally and intramuscularly infection of 100 daily adult hens who had not antibodies against Newcastle disease virus, first clinical signs and death were found after 96 hours after infection. Infectious titer of LG-85 virus was 8,12 lg EID50/0.2 ml, lethal - 8,66 lg ELD50/0.2 ml. Average time of CE death infected with minimum lethal dose was 90 hours, and intracerebral pathogenicity index - 1.11. When infected of adult chickens with virus clinical signs of infection in chickens regardless of the way of infection were detected only in 96 hours after virus administration. Conclusions. By the results of research there were found no significant differences between the biological properties of epizootic ND viruses that are isolated at different times and in different places.