Is the mixture of human cytomegalovirus genotypes frequent in infants with congenital infection at birth in a high seroprevalence population?

It is still not well known, in a population with high human cytomegalovirus (HCMV) seroprevalence, whether a child with congenital infection harbors multiple viral strains at birth, and whether the prolonged viral excretion in these children is secondary to the persistence of the same viral strain. To verify the genomic diversity of HCMV detected in congenitally infected children, the nucleotide viral sequences from urine and/or saliva obtained at birth from 14 newborns with congenital infection and breast milk obtained from mothers of 5 of these children were analyzed. Among the 14 children, 10 had sequential samples until the median age of 10 months. The viral nucleotide sequences in the breast milk were compared with those identified in the respective children at birth. The differentiation of viral strains was based on the variability of 3 regions of viral genes (UL55/gB, UL144, and UL73/gN). In 13/14 children (92.8%), a single genotype was observed at birth. Different viral genotypes were found in 1 child (7.2%). Among the sequential samples from 10 children, the same genotype obtained at birth was detected in 9/10 (90%), and in 1 of them (10%), a genotype change in the urine was found. More than 1 HCMV strain in milk was observed in 2 mothers (2/5, 40%). In a population with high seroprevalence, a single genotype was found in the majority of infected children. Reinfection did not frequently occur in the first months of life. Maternal reinfection does not seem to be a rare event in transmitter mothers.