Isolation from turkeys of a cell-associated herpesvirus antigenically related to Marek's disease virus.

Cytopathic herpesviruses (hvt) were isolated in chick kidney and duck embryo fibroblast cell cultures from blood and kidneys of turkeys from 3 flocks in Indiana and Georgia. In vitro characteristics of these isolates were similar and included highly cell-associated infectivity, syncytial-type cytopathology, type A intranuclear inclusion bodies, inhibition of plaque formation by 5-bromodeoxyuridine (5-budr), and presence of herpesvirus-type particles. The hvt isolates were serologically identical but were distinguishable from other viruses previously isolated from turkeys. The virus was nonpathogenic for both turkeys and chickens through 8 weeks; however, recovery of virus and presence of precipitating antibody indicated that both hosts were susceptible to infection. The hvt could be differentiated from virulent and attenuated isolates of Marek's disease herpesvirus (mdhv), but results of agar gel precipitin, fluorescent antibody, and neutralization studies revealed a substantial antigenic relationship between hvt and mdhv.