Effects of vaccination for Marek's disease on growth of a Marek's-virus-induced transplantable lymphoma in syngeneic and allogeneic chickens.

A study was made of the effects of vaccination with turkey herpesvirus on the growth of tumors following inoculation of lymphoma cells induced by Marek's disease virus (MDV). The cells used were from a transplantable MDV-induced lymphoid tumor (MDT-198) maintained by passaging in syngeneic hosts. Vaccination did not prevent progressive tumor growth or alter subsequent mortality among syngeneic recipients of MDT-198 cells. With allogeneic recipients, however, vaccination had a significant protective effect in that progressive tumor growth and mortality were markedly lowered. Both development of visceral lymphomas and atrophy of thymus and bursa were found at necropsy in both syngeneic and allogeneic hosts when progressive tumor growth occurred at the site of inoculation. The results suggest that it is unlikely that the primary and effective component of turkey-herpesvirus-induced protection against Marek's disease is directed against Marek's-disease-tumor-specific antigens.