Human cytomegalovirus UL55, UL144, and US28 genotype distribution in infants infected congenitally or postnatally

Cytomegalovirus (CMV) is the most common cause of congenital infection. This pathogen exhibits extensive genetic variability in the genes that encode structural envelope glycoproteins, regulatory proteins, and proteins that contribute to immune evasion. However, the role of specific viral strains in the outcome of congenital CMV infection is unclear. Variation in the UL55 gene encoding glycoprotein B (gB), the UL144 gene encoding TNF α-like receptor, and the US28 gene encoding β-chemokine receptor was determined in 60 newborn infants with congenital CMV infection and 90 infants with postnatal or undefined CMV infection. CMV polymorphisms were studied in relation to disease outcome and viral load. Genotyping was performed by a sequencing analysis of PCR-amplified fragments, and the viral load was measured by quantitative real-time PCR. The results demonstrated that (1) the UL55 and US28 genotype distributions were similar among the group of congenital and postnatal CMV infection; (2) the UL144 B1 genotype was more prevalent in congenital than in postnatal infection and was detected in 70% of newborns with asymptomatic congenital infection; and (3) none of the examined genotype was significantly linked with symptomatic CMV infection. No relationship was observed between genotype and viral load. The results revealed that UL55, UL144, and US28 polymorphisms are not associated with the outcome of CMV infection in infants, but the presence of UL144 B1 genotype might be virological marker of asymptomatic infection at birth.