Variations in the cytomegalovirus DNA polymerase and phosphotransferase genes in relation to foscarnet and ganciclovir sensitivity.
BACKGROUND
Identification of human cytomegalovirus (CMV) genome variation is important for understanding mutations associated with drug resistance.


OBJECTIVE
To investigate the CMV resistance to foscarnet (PFA) and ganciclovir (GCV) in patients treated with antiviral drugs and to identify the DNA polymerase (UL54) and phosphotransferase (UL97) gene mutations inducing resistance.


METHODS
Antiviral susceptibility of CMV strains/isolates for PFA and GCV was compared by plaque reduction assay and in situ ELISA. UL54 and UL97 gene mutations were identified by sequencing. Growth phenotype of two CMV recombinants with mutations in UL54 was studied.


RESULTS
Six of seven GCV resistant strains had alterations within the UL97. Five of them also had alterations in the UL54 (F412C, L802M or K513E), previously shown to induce GCV resistance. Seven isolates had no or reduced susceptibility to PFA, which had alterations in the UL54 (D588N, E756K, V781I or L802M). By in vitro mutagenesis, it was shown that a mutation at codon D588N of UL54 conferred 9-fold reduced susceptibility to PFA, while a mutation at codon V781I induced 4-fold reduced susceptibility to PFA and GCV. Both recombinants showed the same kinetics of protein expression (IE, E, and L antigen) and virus yields as the CMV Towne strain.


CONCLUSIONS
The recombinants containing alterations within the UL54 (D588N and V781I) showed a reduced susceptibility to antiviral drugs but no change in the replication rate compared to the CMV Towne.
Mousavi-Jazi
M
M
Swedish Institute for Infectious Disease Control, Microbiology and Tumorbiology Center, Karolinska Institute, SE-171 82, Stockholm, Sweden. mehrdad.mousavi-jazi@smi.ki.se
Schloss
L
L
Drew
W L
WL
Linde
A
A
Miner
R C
RC
Harmenberg
J
J
Wahren
B
B
Brytting
M
M
D000998:Antiviral Agents / Q000494:pharmacology*; D003062:Codon; D003587:Cytomegalovirus / Q000187:drug effects* / Q000235:genetics / Q000276:immunology; D003586:Cytomegalovirus Infections / Q000821:virology; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D024921:Drug Resistance, Multiple, Viral / Q000235:genetics; D017245:Foscarnet / Q000494:pharmacology*; D015774:Ganciclovir / Q000494:pharmacology*; D005814:Genes, Viral; D014644:Genetic Variation; D006801:Humans; D008826:Microbial Sensitivity Tests; D010770:Phosphotransferases / Q000235:genetics*; D014779:Virus Replication
D000998:Antiviral Agents; D003062:Codon; D017245:Foscarnet; D010770:Phosphotransferases; D004259:DNA-Directed DNA Polymerase; D015774:Ganciclovir