Detection And Analysis Of Epstein-Barr Virus Genotypes In EBV-associated Gastric Carcinomas

Objective: To elucidate variations of typesâ… andâ…¡, BamHâ… F and f, BamHâ… I and i and the polymorphism of EBV LMP1 gene in EBV-associated gastric carcinomas (EBVaGC), and to explore the correlation between the gene variations and EBVaGC.Methods: EBV DNA genome was tested in 185 gastric carcinoma tissues and corresponding adjacent tissues by polymerase chain reaction (PCR)-Southern blotting. EBV-encoded small RNA 1 (EBER1) in PCR positive samples was tested by in situ hybridization (ISH) in paraffin-embedded sections . Gastric carcinoma with positive EBER1 signals was confirmed EBVaGC cases. PCR and restriction fragment length polymorphism (RFLP) analysis was used to detect the variations of types 1 and 2, BamHâ… F and f and BamHâ… I and i in Chinese EBVaGC cases from Shandong Province. The C-termini of LMP1 in 12 and 8 EBVaGC cases from Shandong Province and Japan, respectively, were analyzed by PCR and sequencing. The sequences were compared with previously published strains and were characterized on a phylogenetic tree. The difference between Chinese and Japanese isolates was characterized.Results:â‘ There were 13 EBV positive samples in 185 gastric carcinomas (7.03%), but no EBV positive sample in corresponding para-carcinomas. The difference of EBV positive rate between gastric carcinoma and corresponding para-carcinoma tissues was significant (X~2=11.0769,P=0.0009). In our series, age, pathological differentiation, clinical stages, lymph node metastasis and location of cancer were not different between EBV-negative gastric carcinomas (EBVnGC) and EBVaGC (P=0.669, 0.141, 0.259, 0.818, 0.064, respectively), while sex was significantly different between the two groups (X~2=3.9404, P=0.0471).â‘¡All of 12 EBVaGC were grouped into type 1 and prototype F.11 out of 12 EBVaGC cases belonged to type i, and only one belonged to type I.â‘¢10 of 12 Chinese GC isolates (83.3%) and all of the 8 (100%) Japanese EBVaGC isolates belonged to the China 1 strain. Also, B95-8 type isolates were found in 2 of 12 Chinese GC. In the 18 China 1 type isolates, additional mutations outside the signature sequence changes were found. All Japanese isolates (100%) had two or more additional mutations, whereas only 5 of 10 (50%) Chinese isolates had two or more additional mutations.The difference was statistically significant (P=0.0359).Conclusion:â‘ EBV infection is related to the tumorigenesis of gastric carcinoma and is male predominance, but not related to age, pathological differentiation, clinical stages, lymph node metastasis and location of cancer.â‘¡Type 1 ,type i and prototype F are predominate in EBVaGC cases.â‘¢China 1 is the dominant strain in EBVaGC from Shandong Province and Japan. The similarity to that of NPC from China supports the view that China 1 strain represents a geographic associated polymorphism rather than an NPC-associated polymorphism. Japanese isolates show more mutations than Chinese isolates, suggesting a geographic difference between Chinese and Japanese isolates in GC.