Status of endogenous avian RNA tumor virus in Marek's disease lymphoblastoid cell lines and susceptibility of those lines to exogenous RNA tumor viruses.

Three lymphoblastoid cell lines from Marek's disease (MD) tumors, two MD virus (MDV) producer lines (MSB-1 and HPRS-1), and a nonproducer line (RPL-1) were studied for the expression of avian leukosis sarcoma (ALS) viruses. The MSB-1 line was free of all known endogenous expressions, including replicating virus (RAV-O), group-specific (gs) antigens, and chick helper factor (chf). The RPL-1 and HPRS-1 were positive for gs antigens and chf. The RPL-1 and MSB-1 lines showed no evidence of an exogenous DNA provirus by nucleic acid hybridization (HPRS-1 line was not tested for that DNA). All three lymphoblastoid cell lines were susceptible to exogenous infection with both sarcoma and leukosis viruses of subgroup A but varied in susceptibility to subgroups B and C. All were resistant to subgroups D and E.