Amino-acid change in the Epstein-Barr-virus ZEBRA protein in undifferentiated nasopharyngeal carcinomas from Europe and North Africa

Abstract

Different Epstein-Barr-virus(EBV) variants were found to be associated with nasopharyngeal carcinoma (NPC). The type-C variant lacks the BamHI site between the BamHI WI* and I* regions and the type-f variant has an extra BamHI site in the BamHI F fragment. The BNLFI gene (which encodes the LMPI protein) from a nude-mouse-passaged CAO strain and from NPC biopsies from Taiwanese patients also exhibits variations resulting in structural and functional differences in the protein. The BZLFI gene encodes the ZEBRA protein which triggers the EBV lytic cycle. A difference has been observed in 8 amino acids in the ZEBRA sequence in B95-8 (Z95) and P3HRI (ZP3) cell lines. EBV found in NPC biopsies and peripheral-blood cells from Asians was predominantly of the ZP3 type (72%), while 81% of samples from different EBV- associated diseases and peripheral-blood cells from North Africa or Europe were of the Z95 type. We found that an alanine 206 had been replaced by a serine in the Z95 sequence in 72% of the NPC biopsies from European and North African patients. The Zser206 variant is found in a significantly lower percentage (p < 0.001) of other EBV-positive tissues from individuals in the same region (10-33%). In contrast, a 30-bp deletion is observed near the 3' end of the LMPI gene in the majority of EBV (86%) from NPC and peripheral- blood cells from Asians, whereas a significantly lower percentage (p < 0.001) of NPC biopsies from European and North African patients (56%) have this deletion, as do lymphocytes from control individuals from the same region (36 and 55% respectively).