Background: Human Cytomegalovirus (HCMV) infects humans in all geographic areas. Polymorphisms of glycoprotein B (gB) have been used for genotypic characterization of HCMV. However, information of gB genotyping of HCMV in Thailand is not clearly known especially in children.
Material and Method: A cross-sectional study was conducted to assess HCMV infection in 236 HIV seronegative and HIV seropositive children who attended an orphanage in Nonthaburi, Thailand by nested-PCR technique using urine specimens. HCMV gB genotypes were determined by restriction fragment length polymorphism (RFLP), and DNA sequencing technique.
Results: Sixty-one percent (144/236) of the samples were HCMV positive, which consisted of 66.1% (37/56) of the HIV
seropositive children and 59.4% (107/180) of the HIV sero-negative children. Multivariate analysis showed that children
who living in one particular room were independently associated with HCMV infection. Genotypic analysis revealed that the most prevalent genotype in these children was gB1; 85.4% (111/130) followed by gB3; 4.6% (6/130), gB2 and gB4 each at 2.3% (3/130). Mixed gB genotypes were identified in 5.4% (7/130) of the samples.
Conclusion: HCMV infection, in particular gB1 genotype was commonly identified among these Thai orphans. Living in one particular room was associated with getting the infection. To prevent the transmission of HCMV infection in this setting, improvement in hygienic behavior of childcare workers should be focused.

Keywords: Human Cytomegalovirus, Prevalence, gB genotypes, Children, Orphans, Thailand