Abstract: Objective To monitor human cytomegalovirus (HCMV) drug resistance in recipients of hematopoietic stem cell
transplantation by phenotypic and genotypic methods. Methods HCMV clinical isolates was isolated from the urine of
hematopoietic stem cell transplantation recipients treated with GCV. Tissue cell infection median dose (TCID50) of the isolates
was calculated using Reed-Muench method, and their drug susceptibility was determined by plaque reduction assay. We
amplified the UL97 DNA fragment of the virus by nested PCR followed by automated DNA sequencing. Results HCMV
clinical strain isolated from the urine samples of the recipients using a human fibroblast cell line showed a TCID50 value of
10-4.618/0.1ml and a 50% inhibitory concentration (IC50) to GCV of 5.847 μmol/L, suggesting its sensitivity to GCV. Alignment
with the AD169 DNA reference sequence identified 4 point mutations of the virus at 1509 (T-C), 1575 (C-T), 1794 (T-C), and
1815 (C-G), and only the last mutation resulted in one amino acid mutation to D605E. No gene mutation was found in relation
to GCV resistance. Conclusions Phenotypic and genotypic assays were established to examine antiviral drug resistance of
HCMV in recipients of hematopoietic stem cell transplantation. We did not find any drug resistance of the clinical HCMV
isolate.