Multiplicity-dependent induction of viral capsid antigen in Raji cells superinfected with Epstein-Barr virus

A quantitative analysis of Epstein-Barr virus (EBV)-induced early antigen (EA) and viral capsid antigen (VCA) syntheses was carried out in Raji cells superinfected with purified, concentrated P3HR-1 EBV. When the cells were exposed to the virus and assessed by immunofluorescence and immunoprecipitation, EA induction occurred significantly (17%) but not VCA (less than 1%), at a low-input multiplicity of infection (MOI) of 10 EBV DNA copies/cell. In contrast, at a high MOI of 500 EBV DNA copies/cell, the majority of cells were positive for both EA (82%) and VCA (61%). The latter VCA synthesis was accompanied by the replication of EBV DNA. Kinetic studies showed that EA induction was directly proportional to the dilution of the infecting virus, while VCA was made following three-hit kinetics. The implications of these results are discussed in relation to the heterogeneous nature of P3HR-1 EBV and a possible role of EA in VCA synthesis.