Detection and gB genotyping of CMV in Mexican preterm infants in the context of maternal seropositivity.

Introduction: Congenital (CI) and perinatal cytomegalovirus (CMV) infections (PI) can be linked to maternal CMV seropositivity, with fatal consequences in preterm newborns. GB genotyping has been used to analyze genotypic similarity in mothers and infants. The frequency of CMV infection in the context of maternal seropositivity and the viral gB genotypes as well as the genotypic similarity in mothers and preterm infants were investigated.

Methodology: Saliva samples and dry blood spots (DBS) were taken weekly from preterm newborns  from birth until the first month of life, and breast milk samples were taken from their mothers weekly during the first month of lactation. CMV IgG seroprevalence of the mothers and CI or PI in the infants were established. The gB status and genotypic similarities were established retrospectively in DBS and in the breast milk samples.

Results: In total, 387 neonates and 375 mothers were enrolled. The maternal CMV-positive IgG serology was 97.3% (365/375). Neonatal CMV was found in 5.1% (20/387) of newborns, and one infant presented with CMV-compatible symptoms. CI was 2.5% and PI in the first month after birth was 11.8%. GB2 was the most prevalent genotype and was also the genotype preferentially transmitted to newborns by mothers with mixed infections.

Conclusions: CMV PI and CI in preterm infants from highly seropositive mothers was high, but the rate of symptomatic infection was low. The prevalent genotype was gB2, and this genotype was preferentially transmitted to newborns by mothers with mixed infections.