[Studies on the synthesis of Epstein-Barr virus-related antigens induced by superinfection]

Synthesis of Epstein-Barr virus (EBV)-related antigens in Raji cells superinfected with P3HR-1 strain EBV was investigated by immunofluorescence and immunoprecipitation. Purification of the infecting EBV gave a favorable condition for efficient induction of the virus-related antigens and facilitated immunochemical characterization of them. Monoclonal antibodies against the EBV-related antigens were produced and applied for a detailed analysis of the antigens. EBV-related antigen synthesis was shown to be markedly dependent on the virus dose inoculated; early antigens (EA) were readily synthesized at a low multiplicity of infection (MOI), whereas synthesis of the 2 late antigens, virus capsid antigen (VCA) and membrane antigen (MA) was induced only at a high MOI. VCA was induced following three-hit kinetics, suggesting that 3 times the amount of the infecting virus is required for the induction of the antigen. Synthesis of EBV-related polypeptides which constitute these antigens showed similar dependency on the virus dose. Early polypeptides were induced readily at a low MOI, whereas late polypeptides were synthesized only at a high MOI. Furthermore, induction of late polypeptides at a high MOI was accompanied by selective enhancement of the synthesis of a particular early polypeptide with molecular weight of 135K. The implications of these findings are discussed in relation to a possible regulatory function of this 135K early polypeptide in the productive cycle of EBV.