DISTRIBUTION OF CYTOMEGALOVIRUS GENOTYPES CIRCULATING AMONG NEWBORN CHILDREN OF ST. PETERSBURG

The aim of the present study was to perform genotyping of the three most polymorphic regions in the cytomegalovirus (CMV) genome, i.e., UL55 (gB), UL73 (gN), UL75 (gH) in newborns with congenital cytomegalovirus infection (CMVI), to determine distribution of genotypes circulating in the current cohort of patients in St. Petersburg and to compare them with those of CMV circulating in the Russian Federation and worldwide. The study was performed at the Pediatric Research and Clinical Center for Infectious Diseases at the Federal Medical Biological Agency. The study included 61 blood, saliva, urine DNA samples isolated from 26 infants with clinical manifestations of congenital CMV. Molecular genetic methods were used as follows: DNA isolation from biological samples; qualitative detection of CMV DNA by amplification of specific viral DNA fragment using real-time PCR detection of amplicons, preparation of sequencing libraries enriched by hybridization with labeled oligonucleotides. The obtained results of DNA sequencing were processed using bioinformatics methods. According to the results of our study, it was shown that the sequencing of viral DNA segments from various biological samples has yielded different results on CMV genetic polymorphisms. For instance, the genotypes of all three studied regions with satisfactory coverage (according to sequencing data) were obtained more often in urine and saliva than in peripheral blood samples. When analyzing the distribution of genotypes in the UL55 region, the genotype gB7 prevailed being determined in 50% of newborn patients. Analysis of the obtained UL73 region sequencing data allowed to identify the dominant gN4c genotype (37.5%). According to the sequencing results for UL75 region of CMV encoding glycoprotein H, the genotypes gH1 and gH2 showed equal distribution (by 50%). When comparing the genotypes observed in this study with those obtained in Russia and worldwide, some differences in the nucleotide sequence were revealed for the specified regions of CMV genome. Phylogenetic analysis of CMV made it possible to illustrate heterogeneity of gene variant distribution among newborn children in St. Petersburg.