Heterogeneity of Epstein-Barr virus. IV. Induction of a specific antigen by EBV from two transformed marmoset cell lines in Ramos cells.

Infection of cells of the EBV-genome-negative human B-lymphoma Ramos line with viral isolates obtained from two EBV-transformed marmoset cell lines (B95/8; Nyevu) resulted in the induction of a nuclear antigen (RAM-ag) apparently different from other EBV-associated antigen complexes. This antigen is revealed by indirect immunofluorescence and shows no detectable cross-antigenicity with EBNA or any other known EBV-associated antigen. EBV-isolates from P3HR-1 cells fail to induce a similar antigen in Ramos cells although they induce EBNA. No RAM-ag was expressed, either after infection of cells of another EBV-genome-negative human B-lymphoma line BJAB with B95-8 EBV or in a series of EBV-harbouring cell lines. Thus the antigen appears to be cell-line-specific for Ramos cells. It is also induced upon infection of either B95-8 or P3HR-1 converted Ramos sublines with EBV from B95-8 cells. All human sera with RAM-ag-reactivity revealed antibodies against VCA. However, sera from patients with acute infectious mononucleosis containing high anti-VCA-antibodies did not react with RAM-ag. Seroconversion for this antigen apparently more closely coincides with the appearance of EBNA-directed antibodies.