Development and characterization of a Marek's disease transplantable tumor in inbred line 72 chickens homozygous at the major (B) histocompatibility locus.

A serially transplantable Marek's disease (MD) tumor, designated MDCT-RP-3, was developed from an MD-virus-induced lymphoma (GA strain) in a pedigreed female chicken of the inbred B-histocompatible (B2/B2), line 72, and is the first MD tumor transplant to be developed in chickens both syngeneic and selected for susceptibility to MD. The MDCT-RP-3 tumor maintained its female karyotype through at least 80 passages in male 72 chickens. High doses of tumor cells caused progressively growing tumors at 5 days postinoculation and death of young 72 chicks in 7-10 days, whereas allogeneic chicks of other lines were less susceptible. Tumors frequently regressed when doses of tumor cells were low or older chickens were used. MD virus was rescued from MDCT-RP-3 cells in cell culture, and chickens surviving the early transplant response sometimes developed MD lymphomas. The tumor cells expressed MD-tumor-associated surface antigen (MATSA) and T-cell surface antigens. A serum raised in rabbits against MDCT-RP-3 cells and absorbed with normal 72 cells appeared to be reactive against MATSA on all MD tumor cells tested and is probably monospecific. Sera raised against MDCT-RP-3 in chickens also contained MATSA antibodies reactive against heterologous but not homologous MD tumor cells. Protection against transplantation of MDCT-RP-3 cells was not afforded by immunization with turkey herpesvirus vaccine. Some unvaccinated chickens that regressed MDCT-RP-3 transplant appeared to be partially immune to later development of MD lymphomas.