Epstein-Barr virus-induced proteins. IV. Characterization of an EBV-associated phosphopolypeptide

Cells of the Epstein--Barr virus (EBV) non-producing lines NC37 and Raji were induced by the tumour promoter TPA and were labelled with 32P. The analysis by immunoprecipitation with human VCA+EA+ sera revealed that a major phosphopolypeptide with a mol. wt. of 58 000 was specifically precipitated. In addition, a phosphopolypeptide of the same size was the dominant phosphopolypeptide detected in EBV-producing B95-8 and P3HR-1 cells as well as in P3HR-1-superinfected NC37 cells. This phosphopolypeptide seemed to be EBV-specific, because it was not detectable in TPA-treated, but EBV genome-negative, Ramos and BJAB cells. Synthesis of this phosphopolypeptide was inhibited in TPA-treated NC37 cells by treatment with Ara-C. VCA+EA+ sera were found to be more immunoreactive with this phosphopolypeptide than VCA+EA- or EBNA+ sera. Based on these results this phosphopolypeptide may have some immunological relatedness to the EBV-specific early antigen (EA) complex defined by immunofluorescence.