Molecular genetic characterization of the epstein–Barr Virus: a relationship with the clinical features of pediatric infectious mononucleosis

Introduction. Infectious mononucleosis (IM) is an high priority viral infection in children. Epstein-Barr virus (EBV) is the main etiological agent of IM. EBV is classified into two main types EBV-1 and EBV-2. In addition, different variants of the virus are isolated based on individual genes, among which the LMP-1 gene and the oncoprotein it encodes are the most well known. So far, the study of the clinical significance of EBV genetic diversity in EBV-IM in children in Russia has not been conducted. The aim of the study was to evaluate a relationship between EBV LMP-1 molecular genetic variants and clinical and laboratory manifestations of IM in children. Materials and methods. The material of the study was presented by blood leukocyte and saliva samples of children aged 117 years with EBV-IM (n = 69). A total of 132 EBV isolates were studied. For differential detection of EBV-1/EBV-2, we used a previously optimized one-round PCR variant with electrophoretic detection of amplification products in agarose gel. The nucleotide sequences of the C-terminal region of the LMP-1 gene were determined by Sanger sequencing followed by analysis of the obtained sequences using the MEGA X software. Multiple Factor Analysis was used to search for the relationship between LMP-1 variants and clinical and laboratory manifestations of IM (32 signs and 8 groups of signs). Results. It was established that only one type of virus, EBV-1, was identified in all children. At the same time, the severity of clinical manifestations of EBV-IM in children varied significantly (from 15.5 to 35.5 scores in total). Molecular genetic analysis of the sequences of the LMP-1 C-terminal region in Nizhny Novgorod region EBV isolates demonstrated a significant heterogeneity of the viral population, which was not limited only to their grouping according to known variants. According to the frequency of detection, B95-8 was the dominant variant of LMP-1 (60.66.0% of cases), other variants were less common (China 1, NC, Med and China 1+В95-8). It was found that EBV-IM proceeded more easily and with less severity of the intoxication syndrome in cases of infection with a virus having the molecular genetic profile of EBV-1/B95-8, in particular EBV-1/B95-8/E214D. Conversely, EBV-1/Med, as well as EBV-1/Med/L338S, EBV-1/Med/S229T, EBV-1/China 1/L338S and EBV-1/NC/S229T profiles were associated with more severe infection. Conclusion. For the first time, the influence of the genetic diversity of EBV on the clinical manifestations of IM in children was revealed. In the context of the tasks to be solved in this study, it is necessary to conduct a larger-scale and systemic studies in different territories of Russia.