Lack of resistance-associated mutations in UL54 and UL97 genes of circulating Cytomegalovirus strains isolated in a medical center in Taiwan

Human cytomegalovirus (HCMV) is a large DNA virus and a member of the betaherpesvirus family. HCMV infection is extremely common in human populations and can cause severe diseases in immunocompromised hosts. Ganciclovir is the most widely used antiviral drug for cytomegalovirus infection and works by blocking the amplification of HCMV. HCMV strains resistant to ganciclovir have been detected in recent decades and mainly result from mutations in UL97 (protein kinase) and UL54 (DNA polymerase) genes. In order to understand the prevalence of resistance of HCMV in Taiwan, we studied 40 clinical isolates to detect the mutations of UL97 and UL54 that might be related to resistance. The results showed that no mutation known to cause ganciclovir resistance was detected in any strain, but some polymorphisms (N685S, A688V, A885T, N898D in UL54; D605E in UL97) were frequently observed. Our results suggest that resistant HCMV strains are not prevalent in Taiwan.