Epstein-Barr virus and nasopharyngeal carcinoma.

Nasopharyngeal carcinoma, an epithelial tumor which is characterized by marked geographic and population differences in incidence, is consistently associated with the Epstein-Barr virus (EBV). Within the tumor, the EBV DNA is homogeneous and clonal with regard to repeat sequences suggesting that the tumor is also clonal. Expression of specific viral mRNAs or gene products are consistently detected within all of the tumor cells. These data suggest that EBV is an essential component in the development of nasopharyngeal carcinoma. Genetic or environmental co-factors may influence the ability of the virus to express these genes in infected epithelial tissue or may contribute to clonal predominance.