Historical Note: Isolation of the Avian Reticuloendothelial Virus (Strain T)

Record is made of the initial isolation and first 16 passages of the avian reticuloendotheliosis virus (strain T). The original infective liver tissue was taken from a moribund adult turkey having gross lesions similar to those of lymphoid leukosis. During the subsequent 16 passages, in which cellular inocula were used, in both chicks and turkey poults, the infectious agent increased in virulence, causing nearly 100% mortality and decreases in mean survival time. Transmission with cell-free filtrates in chicks and turkey poults was demonstrated.