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.