[UL55 genotype diversity of cytomegalovirus strains isolated from newborns and infants hospitalized in southern Poland].

Studies on cytomegalovirus (HCMV) infections more often draw attention to the differences in tropism, pathogenicity and virulence of the virus depending on its genotype. The aim of this study was to assess the individual gB genotypes which are encoded in UL55 region of HCMV genome in a population of newborns and infants from Southern Poland. Genotypic analysis was carried out on 53 children (16 newborns and 37 neonates) with confirmed HCMV infection. The children were tested several times. A total of 101 samples, mainly urine, less blood, swabs from the upper respiratory tract, in justified cases, the cerebrospinal fluid were used in our study. Both genotyping and quantitative assessment of HCMV were performed using real time-PCR (rt-PCR). For identification of four major gB genotypes in one reaction, a modification of multiplex rt-PCR was used. Studies confirmed the presence of all major genotypes: gB1, gB2, gB3 and gB4 in the examined groups of children. Only in one case, the genotype could not be determined, perhaps it belonged to subtypes outside the detectable majority ofgB genotypes. Genotype gB1 (63.5%) which was slightly more frequent in infants than in neonates, dominated in our studies. The other genotypes occurred at a rate: gB2 - 15.4%, gB3 - 21.2%, gB4 - 28.8%, respectively. Mixed infections, caused by two genotypes were found in 16 (31%) children, mainly in older infants. There were no statistically significant differences in viral load when comparing a group of newborns with infants and single vs. mixed infection, as well as individual genotypes. The observed differences in the proportional occurrence of different gB genotypes in the two study groups of children may suggest various preferences of particular HCMV genotypes in congenital and acquired infections. Moreover, by monitoring of HCMV infection and determination the genotypes in consecutive samples, it could be identified infection acquired during hospitalization in three children.