Nasopharyngeal carcinoma (NPC) is an epithelial malignancy which occurs at high incidence in endemic regions in Southern China, Northern Africa, and among Alaskan Eskimoes but also occurs worldwide in all populations. We have identified the viral sequences which encode RNA in tumor tissue and have identified specific viral transcripts from three regions of the EBV genome which are transcribed in NPC. We will determine when these transcripts are synthesized in lymphoid cell lines in vitro and in the NPC epithelial fusion cell line. NPC-KT. In order to further define which viral functions are expressed in malignant epithelial tissues we will use single-stranded RNA probes representing specific latent functions generated from vectors containing the SP6 and T7 bacteriophage promoters in Northern analyses or in nuclease protection assays. RNA preparations from NPC biopsy specimens an NPC which can be passaged in nude mice, C15, and the NPC cell line, NPC-KT will be compared to RNA from lymphoid cell lines. To facilitate a detailed analysis of viral transcription from the entire genome, we have constructed a cDNA library to NPC RNA in the vector, lambda gt11, by priming cDNA synthesis with oligo dT. Twelve viral specific clones have been identified. The viral cDNA structures will determined by restriction enzyme and sequence analysis. Additional libraries will be repeated from RNA from the same specimen and from additional NPC samples. In some instances cDNA will be primed with oligonucleotides for viraal genes. We will identify hyperplasias or other oropharyngeal malignancies associated with EBV by screening for EBV DNA. The structure of the viral termini will be analyzed to determine if the infected tissue produces linear virion DNA or contains only the episomal form. Monoclonal proliferations will be identified by this assay. Viral transcripts will be analyzed in the EBV-positive hyperplasias through the use of Northern blots, nuclease protection assays and cDNA cloning.
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