QUALITATIVE-ANALYSIS OF THE EXPRESSION OF EPSTEIN-BARR-VIRUS LYTIC GENES IN NASOPHARYNGEAL CARCINOMA BIOPSIES

We recently showed that BZLF1, the gene encoding the Epstein-Barr viru s (EBV) ZEBRA protein, was expressed in all eight nasopharyngeal carci noma (NPC) specimens studied. We present here studies on the expressio n of EBV lytic cycle genes in the same eight NPC biopsies to determine if production of the ZEBRA transactivator could lead to a complete pr oductive cycle. The tumour lesions exhibit a number of different patte rns of limited lytic gene expression. In three out of eight tumours ne ither BRLF1 nor BMLF1 expression could be detected. Otherwise BMLF1 mR NA was expressed in all the other specimens. Three specimens also expr essed BRLF1. Two specimens not only exhibited BZLF1, BMLF1 and BRLF1 t ranscripts, but also expressed the late gene BLLF1 which encodes the m embrane protein gp220. The early gene product BBLF2 could not be detec ted in any of the eight NPC. However, expression of the late gene enco ding the lytic truncated form of LMP1 (D1LMP) was found in seven of th e eight NPC biopsies. Thus, it could be suggested that the EBV abortiv e lytic cycle occurred in most of the NPC studied.