EPSTEIN-BARR-VIRUS AND GASTRIC-CARCINOMA

Epstein-Barr virus (EBV) has been found in most cases of rare gastric lymphoepithelioma-like carcinomas and a small but significant proporti on of common gastric adenocarcinomas. The presence of EBV in gastric c ancer has been detected by polymerase chain reaction and in-situ hybri dization, the latter technique demonstrating EBV in every malignant ep ithelial cell. The carcinoma cells express EBNA1 but not the other EBN As or LMP1. A single fused terminal fragment of the EBV genome was det ected in each of the EBNA1-expressing tumours suggesting that the viru s-positive gastric carcinomas represent a clonal proliferation of EBV- infected cells. EBV antibody titres were elevated in patients with vir us-positive carcinomas and also in those destined to develop EBV-posit ive carcinomas. EBV-specific cytotoxic T-lymphocyte activity was retai ned in patients with EBV-positive carcinomas suggesting that the tumou rs can evade immunosurveillance possibly by only expressing the EBNA1 protein which is not able to be processed and presented. These results implicate EBV as one of the factors contributing to the development o f gastric cancer.