Fractionation of Marek's disease virus-induced lymphoma by velocity sedimentation and association of infectivity with cellular fractions with and without tumor antigen expression.

Cell suspensions of lymphomas induced by Marek's disease (MD) virus were fractionated by sedimentation at unit gravity on a continuous gradient of bovine fetal serum. Cells in various fractions were examined for MD tumor-associated surface antigen (MATSA) by indirect immunofluorescence, using specific antibody, and for viral infectivity by cocultivating fractionated cells with permissive monolayer cells of duck embryo fibroblasts. Most MATSA-bearing cells in the lymphomas sedimented at a sedimentation velocity of greater than 3.0 mm/hour, whereas smaller, slow-sedimentating cells were generally devoid of MATSA expression. Viral infectivity was associated with MATSA-bearing and MATSA-lacking fractions. Within the limits of the experimental procedures used, this observation provided evidence that presence of MD virus genome in lymphocytes doses not result in concurrent expression of detectable MATSA and that MATSA likely represents another stage of interaction between MD virus and certain lymphocytes.