Susceptibility of Marek's disease lymphoblastoid cell lines to infection with influenza and pseudorabies viruses and the protective effect of immunization with influenza virus-infected lymphoblastoid cells.

The susceptibility of 3 lymphoblastoid cell lines (MDCC-MSB1, MDCC-HP1 and MDCC-RP1) derived from Marek's disease tumours to infection with influenza (AoPR8) and pseudorabies viruses was studied. MSB1 and HP1 were more susceptible to infection with influenza virus than was RP1. It was shown in the case of HP1, which was studied in greater detail, that although the majority of the cells synthesized influenza virus haemagglutinin when infected at high multiplicity, only a small proportion produced mature infectious particles. The results obtained from both high and low multiplicities of infection suggested that infection with AoPRs was abortive in the majority of the cells of all 3 cell lines. Infected cultures remained viable when subcultured over several days. All 3 cell lines were resistant to pseudorabies virus. The block in pseudorabies virus replication probably occurred after adsorption. Immunization of chickens with HP1 lymphoblastoid cells superinfected with influenza virus AoPR8 and inactivated with glutaraldehyde gave better protection against Marek's disease than immunization with uninfected HP1 cells.