Molecular and genetic characteristics of Nizhny Novgorod Regionepstein–Barr virus isolates in children with infectious mononucleosis and healthy virus carriers

Abstract

Numerous foreign studies evidence about a pronounced heterogeneity of the Epstein-Barr virus (EBV) populationcirculating throughout the world. Various EBV classifications have been proposed. The attention of Russian researchers has focused on the study of the structural and functional polymorphism of the EBV LMP-1 oncogene in the context of oncological diseases in adulthood. The aim of the work was to assess EBV molecular genetic diversity in children with EBV infection in the Nizhny Novgorod region. There were analyzed blood leukocyte and saliva specimens from children aged 117 years with EBV-infectious mononucleosis (n = 69) and sex- and age-matched healthy virus carriers of (n = 32). A total of 178 EBV isolates were studied. For differential detection of EBV-1/EBV-2, we used an optimized one-round PCR variant with electrophoretic detection of amplification products in agarose gel. Nucleotide sequences of the LMP-1gene C-terminal fragment were determined by Sanger sequencing. Bioinformatics data analysis was performed using MEGA X software. As a result, during EBV-infectious mononucleosis, only the EBV-1 type was detected in all children, among healthy virus carriers EBV-1 (93.84.3%) and EBV-2 (6.24.3%). Based on the EBV classification according to R.H. Edwards et al. the strain affiliation of EBV isolates was determined. A total of five variants of LMP-1 were identified, namely B95-8, China 1, Med, NC and Alaskan, among which B95-8 dominated. The LMP-1 Med+, China 2, and China 3 variants were not found in any of the studied samples. It has been shown that the region of tandem repeats makes a significant contribution to the genetic diversity of the EBV population. A total of 100 amino acid substitutions were identified, of which the most common in the Nizhny Novgorod region EBV isolates are G212S, S366T, E328Q and S309N. A comparative analysis showed that strains, deletions, repeats, amino acid substitutions in EBV isolates from biological samples in children with infectious mononucleosis had common characteristics with a group of healthy virus carriers. In the active form of EBV infection, the appearance of structurally heterogeneous EBV sequences isolated from blood leukocytes and saliva from a single source was noted. Thus, for the first time, the molecular genetic diversity of EBV in children with various forms of EBV infection was assessed, which is the basis for the prospective development of clinical and epidemiological studies of EBV infection at a new methodological level.