Experimental Transmission of Reticuloendotheliosis in Turkeys With the Cell-Culture-Propagated Reticuloendotheliosis Viruses of Turkey Origin 2

Abstract

Reticuloendotheliosis virus (REV) strains MN67 and MN81, previously isolated from naturally occurring reticuloendotheliosis (RE) of turkeys, were propagated in turkey embryo fibroblast cultures. Cell-culture-propagated REV were inoculated in 1-day-old turkey poults that were subsequently raised in isolation conditions for 18 weeks. Turkey poults were also exposed by contact with RE-inoculated turkeys to study possible horizontal transmission. Both REV strains MN67 and MN81 were pathogenic for turkey poults and were horizontally transmitted in turkeys. The incubation period of the disease was 8–11 weeks. REV produced 10–33% mortality in turkeys, and macroscopic RE lesions were observed in the livers, spleens, intestines, pancreas, and kidneys. Peripheral nerve enlargement was also seen occasionally. Microscopically, the lesions observed were composed of neoplastic lymphoreticular cells. In addition, neoplastic lymphoreticular cell infiltrates were present in the hearts, gonads, muscles, and brains. REV was isolated from the tissues of turkeys experimentally inoculated with REV, and antibodies to REV were detected in these turkeys. Uninoculated controls showed neither RE lesions nor REV infection. Turkeys of all groups were free of Marek's disease virus infection.