Cell‐killing by Epstein‐barr virus: Analysis by colony inhibition procedure

The P3HR‐1 and B95‐8 strains of Epstein‐Barr virus (EBV) were cytocidal for EBV‐carrier human cell lines, as revealed by a colony inhibition procedure. The cytocidal activity was proportional to virus dose added. The cell killing was neutralized by anti‐EBV antibody‐positive but not ‐negative human sera. When the relative sensitivity to ultraviolet light of EBV activities was examined, the cytocidal activity was much more resistant than the viral infectivity as assayed by early antigen‐forming activity (P3HR‐1 virus) or leukocyte‐transforming activity (B95‐8 virus), but it closely paralleled the ability to adsorb to cells.