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Abstract: Epstein-Barr virus (EBV) BZLF1 gene can trigger EBV from latent infection to lytic replicative phase. The functions of BZLF1 are well known, while little is known about its gene polymorphism. In order to elucidate the sequence variations of BZLF1 and its association with malignancies, we analyzed BZLF1 gene in 24 EBV-associated gastric carcinomas, 41 nasopharyngeal carcinomas and 24 throat washing samples from healthy donors in Northern China using PCR-direct sequencing method. Three types and 8 subtypes of BZLF1 were identified. A dominant type BZLF1-A was found in 67 of 89 (75.3%) isolates. Type BZLF1-B was characterized by a common Ala deletion at residue 127, which was detected in 21 of 89 isolates (23.6%). Type BZLF1-C contained only one isolate (GC103), which had the same sequence with the prototype B95-8. Among 3 functional domains of BZLF1 protein, the transactivation domain had most mutations, followed by the bZIP domains (the DNA binding domain and dimerization domain). No prevalence of any subtypes or mutations in the functional domains among three specimen groups was found (P > 0.05). Our study indicates that BZLF1 subtypes and amino acid changes in functional domains are not preferentially associated with EBV-associated gastric carcinomas or nasopharyngeal carcinomas in Northern China. BZLF1 gene variations are geographically restricted rather than tumor-specific polymorphisms. [Copyright &y& Elsevier]

In order to study the mechanism of Epstein–Barr virus (EBV) infection in gastric carcinoma cells, we characterized the EBV infection in signet ring cell line HSC-39, derived from a human gastric carcinoma. HSC-39 cells were highly susceptible to cell-free EBV infection by Akata and P3HR-1 EBV strains. EBV nuclear antigen (EBNA) and EBV-encoded small RNA (EBER) were detected in the infected cells. Akata and P3HR-1 EBV-infected cell clones were isolated by a limiting dilution technique. The Akata and P3HR-1 EBV-infected clones differed from each other in morphology and growth patterns. Akata EBV-infected clones had lower growth rates than did P3HR-1 EBV-infected clones in both liquid and soft agar mediums. Both the infected HSC-39 cells and the clones expressed EBNA1 and EBER, but did not express EBNA2, latent membrane protein (LMP) 1 and LMP2A. The Q promoter (p), but not the Cp/Wp for EBNA transcription, was active in the infected HSC-39 cells and all clones. No lytic infection was observed in either infected parental cells or any clones. Uninfected HSC-39 cells did not express a principal EBV receptor CD21; however, Akata but not P3HR-1 EBV-infected clones expressed low levels of CD21 mRNA. These results demonstrate that the cellular phenotypes of HSC-39 cells are altered by EBV infection in strain-specific manner. We propose the HSC-39 cell line as a model target for the study of the mechanism and significance of EBV infection in gastric carcinoma. [Copyright &y& Elsevier]