Epstein–Barr virus (Orthoherpesviridae: <i>Lymphocryptovirus</i>) among Russian ethnic groups: Prevalence of EBV types (EBV-1 and EBV-2), <i>LMP1</i> gene variants and malignancies

Abstract

Introduction. The discovery of two EBV types (EBV-1 and EBV-2) has stimulated the study of their prevalence in populations and association with malignancies.
 Objective. To study the prevalence of EBV-1 and EBV-2 types among ethnic groups in Russia, to analyze PCR products of the LMP1 gene in virus isolates, and to evaluate the contribution of EBV types to the incidence of malignant neoplasms.
 Materials and methods. EBV isolates from oral lavages of the Republics Adygea, Kalmykia, Tatarstan and the Moscow Region (MR) representatives were studied by nested PCR for the belonging to EBV-1 and EBV-2 types. LMP1 amplicons obtained by real-time PCR from viral isolates DNA were classified and sequenced on an automatic DNA sequencer ABI PRISM 3100-Avant (USA). The sequencing results were analyzed using Chromas 230 and Vector NT programs (Invitrogen, USA). The reliability of the obtained data was assessed using statistical packages Statistica for Windows, 10.0.
 Results. The prevalence rates of EBV-1 and EBV-2 in representatives of four ethnic groups were compared with the incidence rates of some tumors in the population of three Republics and MR.
 The dominant persistence of the transforming in vitro EBV-1 type in representatives of the Republic of Tatarstan and MR correlated with a high incidence of gastric cancer and lymphomas in the population of these territories. On the contrary, predominant infection of the non-transforming in vitro EBV-2 type and both types of the virus in approximately the same percentage of representatives of Adygea and Kalmykia, respectively, correlated with a lower level incidence of above tumors in populations of these Republics. The differences between the incidence rates of neoplasms in the compared ethnic populations were statistically insignificant (p 0.05). LMP1 variants of viral isolates did not reflect either the level of EBV persistence types or the incidence of tumors.
 Conclusion. Infection of ethnic groups with EBV-1 and EBV-2 may vary significantly under the influence of various factors. The predominance of the in vitro transforming EBV-1 type in the population did not increase the incidence of tumors due to cases associated with the dominant virus type.