Immunological studies on the Epstein—Barr virus encoded alkaline deoxyribonuclease found in virus-producing lymphoblastoid cells

Antisera were raised against a purified recombinant form of the Epstein-Barr virus (EBV) alkaline deoxyribonuclease (DNase) expressed in Escherichia coli. These sera were shown to be reactive with lymphoblastoid cells expressing EBV antigens (B95-8, P3HR-I and Raji). Immunostaining studies of cells expressing EBV antigens revealed that the DNase was a component of the restricted early antigen complex of EBV. Western blot analysis of these chemically induced cells revealed that the polypeptide associated with the EBV DNase has an Mr of approximately 55000, slightly greater than that of the recombinant form, suggesting that the protein undergoes some form of posttranslational modification during virus replication. The DNase enzymic activities observed in B95-8, P3HR-1 and Raji cells following chemical induction were neutralized using the specific antiserum. A detailed examination of protein extracts from the nude mouse-passaged nasopharyngeal carcinoma cell line C-15 failed to detect any antigenic or biochemical evidence for the presence of the DNase. Immunostaining of biopsies of oral 'hairy' leukoplakia with the antisera against EBV DNase revealed high level expression in the more differentiated spinous layers of the epithelium, a pattern of reactivity identical to that observed for other lytic cycle antigens.