A novel early antigen associated with Epstein-Barr virus productive cycle.

A murine monoclonal antibody (mAb) 92A recognized a 48-kilodalton Epstein-Barr virus (EBV) early antigen (EA). The mAb stained nuclei of EBV-activated P3HR-1, B95-8 and Akata cells in a distinctive, microgranular immunofluorescence pattern. The 92A antigen was sensitive to methanol-fixation. Expression of the 92A antigen in those cells paralleled diffuse (EA-D) and restricted (EA-R) components of EA, and viral DNA (vDNA) replication. Phosphonoacetic acid did not inhibit expression of the 92A antigen. The colocalization of 92A antigen, EA-D, and vDNA was observed in viral replication compartments of B95-8 cells. On the other hand, in P3HR-1 virus-superinfected Raji cells the percentages of 92A antigen-positive cells were at much lower levels than were EA-D and -R positive cells. Immunofluorescence staining with 92A mAb was blocked by pretreatment with EBV-positive human sera, but not with EBV-negative sera. We conclude that 92A mAb recognizes a novel EA which may function in vDNA replication.