Background: Congenital cytomegalovirus (CMV) infection is caused by maternal primary infection as well as CMV reinfection or reactivation during pregnancy, although differences in the clinical impact between these modes of infection remain to be clarified. Objectives: To investigate the latest prevalence and risk of multiple CMV infection in healthy pregnant women, as well as the types of maternal CMV infection associated with congenital CMV infection. Study design: Seroprevalence against CMV and IgG subclasses were determined in 344 serum samples from healthy pregnant women in Japan. CMV genotype and serotype were also determined in 18 pairs of mothers and neonates with congenital CMV infection identified in our CMV screening program. Results: Thirty-two percent of the pregnant women were seronegative, while 66% of CMV seropositive women had IgG3 antibodies against one epitope on glycoprotein H (gH) as the major subclass, and 52% had IgG1 antibodies against one epitope on glycoprotein B (gB). Only a single genotype determined by CMV gH neutralizing epitope was found in the urine from the 18 neonates with congenital CMV infection, even though one case possessed antibodies against multiple CMV strains. In that case, the antibodies against the strain not detected in the urine from the infant disappeared within one month after birth, whereas the antibodies against the infecting CMV strain continued to be detected at 12 months after birth. Conclusions: Two (11%) of 18 cases of congenital CMV infection occurred via maternal CMV reinfection. Maternal humoral immunity did not prevent congenital CMV infection with another gH subtype.
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