Herpes-Type Virus Isolated in Cell Culture From Tumors of Chickens With Marek's Disease. I. Studies in Cell Culture

Summary

A herpes-type virus (HTV) from tumors of chickens with Marek's disease (MD) has been propagated in cultured chicken kidney (CK) cells. The cytopathic effect (CPE) of this virus in CK cells is described. No evidence of infectivity was found in the supernatant of infected cultures, and no infectious virus could be extracted by disruption of infected cells. A plaque assay under fluid medium is described and was used to demonstrate that up to 9 days after culture inoculation there is little evidence of secondary plaque production. With infected cultured cells as an inoculum for CK monolayers, it was demonstrated that the adsorption period extended over 24 hours. The inclusion of antiserum in the culture medium did not significantly inhibit the number of microplaques produced by a standard inoculum of infected cells. Cultured CK cells infected with the HTV at different passage levels between the fourth and twentieth produced MD when inoculated into day-old chicks. No tumors developed during 8 months' observation when newborn hamsters were inoculated subcutaneously or intracerebrally with CK cells infected with HTV. Infected CK cells produced pocks when inoculated onto the chorioallantoic membrane of embryonated hens eggs. The CPE and method of spread of the virus through the cultures are discussed.