Two monoclonal antibodies directed against Epstein-Barr virus (EBV)-induced membrane antigens (MA) were isolated in this study. One of the monoclonal antibodies, designated 2F5.6, was an IgG2 which, as detected by membrane and fixed cell immunofluorescence, reacted with MA-positive lymphoblastoid cell lines that produced transforming EBV but not with the MA-positive P3HR-1 cell line that produced the lytic, nontransforming strain of this virus. This antibody precipitated the Mr 320,000/350,000 glycoprotein from B-95 virus infected cultures and the Mr 300,000 and 220,000/250,000 glycoproteins from Raji cells superinfected with P3HR-1 virus but did not precipitate any ofthese EBV-specific glycoproteins from the P3HR-1 cell line. In contrast, the second Imonoclonal antibody, IgM designated B10.3, reacted with all virus-producing cell lines including the P3HR-1 cell line. The identity of the glycoprotein that serves as the target for this antibody is still unknown. Neither antibody had neutralizing activity against the B-95 or P3HR-1. strain of EBV. These results indicated that the 2F5.6 monoclonal antibody was directed against an antigenic determinant on the major membrane glycoprotein which is common to transforming strains of EBV but absent from the lytic P3HR-1 strain whereas the B10.3 monoclonal antibody was directed against a group-specific EBV-induced membrane determinant. The Epstein-Barr virus (EBV) has been studied extensively because of its possible involvement in the etiology of nasopharyngeal carcinoma and African Burkitt lymphoma. Such studies have led to the identification of EBV isolates with different biological activities (1). The two prototype viruses that have been utilized extensively in these investigations are the P3HR-1 virus produced by a subline derived from a cell line established from an African Burkitt lymphoma biopsy sample (Jijoye) (2) and the B-95 virus isolated from a patient with infectious mononucleosis and propagated in marmoset cells (3). Although the viruses produced by both of these cell lines are morphologically similar and can be neutralized by sera from EBV-infected individuals, the biological activity and biochemical composition of these viruses show some significant, differences.The P3HR-1 virus is cytolytic for B lymphocytes, the target cell for EBV, and has apparently lost its ability to immortalize or transform B lymphocytes (4, 5). Therefore, it is categorized as a lytic nontransforming virus. This virus does, not induce the expression of the EBV-induced nuclear antigen (EBNA) upon infection ofB lymphocytes nor does it stimulate DNA synthesis, two. characteristics of transforming strains of EBV (6). Upon superinfection of EBV-genome-positive nonproducer cell lines with P3HR-1 virus, the synthesis ofthe early antigen (EA) complex is initiated followed by a shutdown ofcell synthesis of macromolecules. and the eventual death of the infected cell (7,8).In contrast, transforming strains of EBV, including the B-95 virus, generally do not initiate synthesis of the EA...
