Identification of a novel EBV-induced membrane glycoprotein of 43 kDa with H667 MAb

Using purified B95-8 Epstein-Barr virus (EBV), a MAb designated H667 was produced. We demonstrated by indirect membrane immunofluorescence (IF) on six EBV producer cell lines and by immunoelectron microscopy that H667 reacted with a membrane antigen. H667 recognized a 43-kDa EBV protein (p43) as determined by immunoblotting using purified EBV from the six producer cell lines. Phosphonoacetic acid treatment of B95-8 cells was associated with the disappearance of p43, indicating that it was a late antigen. This antigen was shown to be a glycoprotein by incorporation of [14C]glucosamine and was shown to contain an N-asparagine-linked glycosyl group by its sensitivity to tunicamycin. It was named gp43. The H667 MAb inhibited B95-8 EBV cord blood lymphocyte transformation only when a low inoculum was used but failed to inhibit EA induction in Raji cells by P3HR1 EBV. Human sera reactivity against the gp43 antigen was studied. By the immunoblotting method, using H667 immunoaffinity chromatography-purified gp43, we showed that 70.9% of the human sera tested had antibodies directed against gp43. By IF blocking tests, we found that only 12.5% of the sera tested were reactive, indicating that the epitope corresponding to the H667 MAb was not the most immunogenic gp43 epitope.