Inoculation experiment of Marek's disease vaccine contaminated with a reticuloendotheliosis virus

Two-day-old chicks were inoculated with one or ten doses of Marek's disease (MD) vaccine originated from the herpesvirus of turkeys (HVT) and contaminated with a reticuloendotheliosis virus (REV). As a result, they presented such symptoms as abnormality in the vane of remiges, undergrowth, anemia, and leg paralysis. These symptoms were the same as those induced by the same vaccine among chicks in the field. Control chicks which had been placed in the same house as those inoculated with the vaccine exhibited no abnormal signs. A persistent infection with REV was noticed in the vaccine-inoculated group. A horizontal infection with REV was the highest in the control group, which was followed by the group inoculated with one dose and that inoculated with ten doses in the order listed. The antibody response of chicks to HVT and MD virus was also inhibited by REV.