The researchers select 100 cytomegalovirus (CMV) DNA samples from patients diagnosed with CMV infection. Patients include bone marrow transplant patients, pregnant women and newborns. The researchers determine viral load by real-time polymerase chain reaction (PCR). They amplify CMV-gB sequences by PCR and type by sequencing and restriction fragment length polymorphism (RFLP). The researchers obtain clinical data from patients' records. They examine association between patients' clinical status and CMV-gB genotype and viral load.