Expression of the Epstein-Barr virus BamHI A fragment in nasopharyngeal carcinoma: evidence for a viral protein expressed in vivo.

Afamily ofmRNAsthataretranscribed rightward through theBamHIA fragment havebeendetected in C15,anasopharyngeal carcinoma (NPC)whichhasbeenpassaged innudemice.Northern (RNA)blot hybridizations indicate that these RNAsarealso expressed inthree other NPCswhichhavebeenestablished in nudemiceandinanNPCobtained atbiopsy. Moreover, hybridization insitu detected transcription from BamHIAin12NPCsand1Epstein-Barr virus (EBV)-containing carcinoma oftheparotid gland. Ineachcase, transcription wasdetected inallofthemalignant epithelial cells. Transcription wasnotdetected intwocases ofEBV-positive lymphoma biopsies byinsitu hybridization norinlatently infected EBV-positive lymphoblastoidcell lines byNorthern blothybridization. Theconsistent transcriptioh ofthese sequences inlatently infected epithelial malignancy butnotinlymphoid cells suggests that this viral function isassociated withlatent EBVinfection ofepithelial cells. Sequence analysis ofacDNAsynthesized fromtheC15tumor, representing the3'endofBamHIA messenger RNA,revealed anopenreading frame(ORF). Translation ofthis ORFin vitro produced several peptides thatwereimmunoprecipitated withantisera frompatients withNPC.The detection ofantibodies totheprotein encoded bytheORFpresent intheBamHIAcDNAindicates that BamHI Aencodes aprotein whichisexpressed invivoandisantigenic.