The LMP1 gene isolated from Russian nasopharyngeal carcinoma has no 30-bp deletion

The Epstein-Barr virus (EBV) is tightly linked to the induction of undiffer entiated nasopharyngeal carcinoma (NPC), a tumour endemic in certain areas of southeast Asia. The LMPI gene encoded by EBV is a classical oncogene due to its ability to transform rodent fibroblasts. LMPI is absolutely essenti al for transformation of B cells by the virus and is one of the few EBV gen es found to be expressed in NPC, It was originally shown that the LMPI gene from NPC harbours a deletion of 30 bp in the 3' part of the gene. However, this deletion is also present in the virus spread in healthy people of the areas endemic for NPC and also in other EBV-positive tumours as well as in healthy carriers. We isolated and sequenced the LMPI gene obtained from ti ssue of 7 Russian patients with NPC and I German patient with an NPC-like t umour of the parotid gland (PG) and compared them with the LMPI gene isolat ed from peripheral blood lymphocytes (PBLs) of 6 Russian and 4 German healt hy EBV-positive carriers, Neither the Russian NPC cases nor the German NPC- like tumour harboured an LMPI gene with the 30-bp deletion, while I Russian and 2 German carriers contained the LMPI gene with the 30-bp deletion. In addition, the LMPI gene isolated from PBLs of the German patient was virtua lly identical to the gene isolated from the primary tumour, Functional anal ysis showed no correlation between the presence or absence of the 30-bp del etion and the level of induction of the transcription factors NF kappaB and jun/AP-I caused by LMP I. These data indicate that the 30-bp deletion is n ot a factor predisposing for NPC, Comparison of the DNA sequences revealed that the LMPI genes present in the NPCs most likely represent the "strain" persisting in the general population. (C) 2001 Wiley-Liss, Inc.