Subtyping of cytomegalovirus strains obtained from immunocompetent children.

We analyzed 33 clinical isolates of cytomegalovirus (CMV) obtained from immunocompetent Japanese children. DNA was extracted from infected MRC-5 cells and we amplified CMV glycoprotein-B (gB), major IE (MIE), DNA polymerase and glycoprotein-H (gH) genes using PCR. Among the 33 clinical isolates, 24 were identified as gB group 1, one as group 2, 6 as group 3, and 2 as simultaneous infections with group 1 and group 3 strains. Clinical isolates of CMV have also been classified into 18 MIE, 8 DNA polymerase and 15 gH genotype patterns by restriction fragment length polymorphism (RFLP). RFLP analysis is useful in molecular epidemiological studies of CMV infection in immunocompetent individuals.