Reticuloendotheliosis group virus pathogenic to chicken isolated from material infected with turkey herpesvirus (HVT).

Izawa et a. (2) reported isolating HT-1 strain of herpesvirus of turkey (HVT) from Japanese turkeys. This paper describes the isolation of a C-type particle pathogenic to chickens coexisting in cells infected with HT-1 strain. The HT-1 strain used, after isolation from turkeys, was passaged 18 times in primary chick kidney, 17 times in primary duck kidney, and 7 times in primary duck embryo fibroblast (DEF) cell culture. We further passaged it in DEF cells 9 times before the present tests. When HT-1-infected DEF cells were examined by electron microscope, C-type virus particles were observed along with herpesvirus particles. To eliminate the HVT, infected cells were frozen and thawed three times and the supernate was obtained after centrifugation at 5,000 rpm for 20 minutes. Anti-HVT hyperimmune chicken serum was added to the supernate, and the mixture was incubated at 37 C for 60 minutes and then inoculated onto DEF. The entire procedure was repeated three times. No HVT cytopathic effect (CPE) was observed on infection of DEF cells with undiluted cell culture supernate. Also, HVT was not detected by direct immunofluorescence, and herpesvirus particles were not observed on electronmicroscopy. However, numerous C-type particles were observed in the infected cultures. Also, a CPE was observed in DEF cultures 7 to 10 days after infection.