Expression of the Epstein-Barr Virus Immediate Early Gene, BZLF1, in Nasopharyngeal Carcinoma Tumor Cells

The Epstein-Barr virus has been shown to be associated with nasopharyngeal carcinoma (NPC). We have shown that anti-ZEBRA transactivator antibodies were present in sera of most NPC patients. We investigated the expression of the BZLF1 gene in fresh NPC tumor biopsies. RNA transcripts of this gene could be detected by in situ hybridization. This expression is restricted to tumor cells and is not present in infiltrating lymphocytes. ZEBRA protein could also be visualized in a fraction of these cells. A cDNA library made from polyadenylated mRNA of an NPC tumor biopsy was constructed and analyzed by PCR. Transcripts of the BZLF1 gene were unspliced. incompletely spliced, or fully processed. A transcript lacking the middle exon was also observed. Fully processed BZLF1 mRNA was also detected in six more NPC tumor biopsies.