Pathogenicity of a Field Marek's Disease Virus Isolate (VUB-83) for Chickens of Three Genetically Different Types

Abstract

Jurajda V., R. Halouzka: Pathogenicity of a Field Marek's Disease Virus Isolate (VUB-83) for Chickens of Three Genetically Different Types. Acta vet. Brno, 58,1989: 273-279. The incidence of Marek's disease (MD) after parenteral infection of chickens of three genetically different types (Hybro pullets, final White Hisex hybrids and Brown Leghorn chickens) with a field isolate (VUB-83) of MD virus was followed under laboratory conditions. MD was diagnos­ ed on the basis of gross lymphomas or, in their absence, on the basis of histological examination in chickens that died during the 105-day observation period. The incidence of MD lymphomas in chickens that died and the mean time to death showed significant differences between the three groups in the following order: Hybro (95.8 %; 78.1 days), Hisex (75 %; 55.5 days) and BrL (57.2 %; 43.1 days). Total mortality and the incidence of MD was lowest in Hybro pullets (63.2 % and 68.4 %), differing significantly from the values observed in Hisex (94.1 % and 94.1 %) and BrL (95.6 % and 100 %) chickens. The total incidence of MD lymphomas showed no significant differences between the three groups (Hybro, 65.8 %; Hisex, 70.6 %; BrL, 53.3 %). In all the chickens tested the most frequently tumour-affected organs after infection with isolate VUB-83 were the liver (34.7 %) and the spleen (29.5 %). The early mortality syndrome was not observed.