Nasopharyngeal Carcinoma (NPC) in Russia and Epstein - Barr Virus Types: Analysis of the Influence of Gender, Ethnic and Age Factors on the Virus Types Spread in NPC Patients

Introduction: The discovery of two molecular types of Epstein-Barr virus, EBV-1 and EBV-2, with different biological properties, stimulated the search for new neoplasms associated with each type of the virus. Objective: The aim of this study was to analyze the prevalence of EBV-1 and EBV-2 in NPC patients from different climatic and geographical regions of Russia, representatives of different gender, ethnic and age groups of patients. Materials and Methods: Using nested PCR EBV types were determined in blood plasma of NPC and other non-EBV-associated tumors of the oral cavity (OTOC/EBV-) patients from the North Caucasus (NCFD) and the Central (CFD) Federal Districts of Russia. IgG and IgA antibody titers to viral capsid antigen (VCA) were determined by indirect immunofluorescence. Results: The studies carried out have shown that NPC and OTOC/EBV- patients were infected with both EBV types in roughly the same ratio. There were also no statistically significant differences in serological activities of NPC patients infected with EBV-1 or EBV-2. The prevalence of EBV-2 types 1 and 2 was not influenced by gender or ethno-geographic affiliation of NPC patients. The only difference was EBV-2 predominance in NPC patients under 60, and EBV-1 predominance in those over 60 years old. Conclusion: The absence of a predominance of one of the EBV types in NPC patients indicates that neither EBV-1 nor EBV-2 is strictly NPC-associated in Russia, and that different ethnic and climatic-geographical factors in the spread of virus types in NPC patients are not playing an essential role.