EB viral antigens in burkitt tumor biopsies and early cultures

The emergence of cells producing EB viral antigens in cultures of Burkitt tumor biopsies was studied by means of immunofluorescence techniques. Definitely or questionably positive cells were seen in acetone‐fixed smears of 6% and 29% of the biopsies, respectively, which amounted to no more than a few cells among several hundred thousands. Yet in culture, specifically stainable cells often appeared within 3 to 10 days, occasionally in substantial numbers (up to 5%). Repeated biopsies from the same donors gave remarkably similar results. In time all cultures which developed into lines showed the presence of EBV. Arginine‐free medium failed to facilitate emergence of EBV antigen‐producing cells in young cultures or to increase their number, unless about 0.5% or more of the cells in the control cultures were productively infected. The implications of these findings are discussed.