ANALYSIS OF THE UL97 PHOSPHOTRANSFERASE CODING SEQUENCE IN CLINICAL CYTOMEGALOVIRUS ISOLATES AND IDENTIFICATION OF MUTATIONS CONFERRING GANCICLOVIR RESISTANCE

The UL97 phosphotransferase coding sequences of clinical cytomegalovir us (CMV) isolates, 10 resistant and 11 sensitive to ganciclovir, were compared to define mutations associated with drug resistance. In each ganciclovir-resistant isolate, a mutation was found that resulted in a n aminoacid substitution at codon 460 (4 isolates), codon 594 (2 isola tes), or codon 595 (4 isolates). No sensitive isolate carried any of t hese mutations. Marker transfer studies showed that each mutation was capable of conferring ganciclovir resistance to the laboratory CMV str ain AD169. Rapid diagnostic tests based on DNA amplification and restr iction enzyme analysis were developed for these mutations. Specific mu tant DNAs were detected when they constituted at least 10% of the popu lation in the specimen. Several mutations in UL97 appear to be common markers for ganciclovir resistance, and their detection may be a rapid alternative to conventional cell culture susceptibility testing.