Are particular Epstein-Barr virus strains linked to disease?

The presence of the well-established EBV types (type 1 and 2) in cancers seems merely to reflect their prevalence in the population; the EBNA genes which determine type 1 and 2 are not usually expressed in cancers. In contrast, LMP1 is frequently expressed in nasopharyngeal carcinoma and a variant form of LMP1 has been linked with this disease. This form of LMP1 is also more transforming in cell culture assays. Many other examples of minor sequence variation have been reported but there is no evidence that they are of functional importance in EBV-associated disease.