IN-SITU DETECTION OF THE EPSTEIN-BARR VIRUS-ENCODED NUCLEAR ANTIGEN-1IN ORAL HAIRY LEUKOPLAKIA AND VIRUS-ASSOCIATED CARCINOMAS

A new monoclonal antibody has been used to examine immunohistochemical ly the expression of the Epstein-Barr virus (EBV)encoded nuclear antig en (EBNA) 1 in virus-associated epithelial lesions, EBNA1 was detected in the tumour cell nuclei of 10/13 undifferentiated nasopharyngeal ca rcinomas and of 10/10 EBV-associated gastric carcinomas, EBNA1 was als o detected in 13 of 16 oral hairy leukoplakia (HL) samples, where its expression was confined to nuclei in the upper epithelial cell layers whilst basal epithelial cells were negative. This observation is in ag reement with previous studies demonstrating the absence of latent EBV infection in the basal cell compartment of HL and suggests an essentia l role for EBNA1, not only in latent EBV infection but also in virus r eplication.