Isolation of infectious EB virus from the epithelial tumour cells of nasopharyngeal carcinoma.

Evidence of herpesvirus replication has been found by light and electron microscopy in the malignant epithelial cells of two out of six nasopharyngeal carcinomas (NPC) examined directly after growth in nude mice to eliminate non-malignant infiltrating cells. The agent has been identified as EB virus by immunofluorescence tests for EB virus capsid antigen, and has been shown to be biologically active by its ability to infect and transform foetal cord blood lymphocytes. Lymphoblastoid cell lines which express the EB virus nuclear antigen have been established from the transformed foetal lymphocytes, and thus carry the first isolate of the virus from the actual epithelial tumour cells of NPC, in a form suitable for further investigation. The results are discussed in terms of the relationship of EB virus to NPC epithelial cells.