Cytomegalovirus UL97 mutations associated with ganciclovir resistance in immunocompromised patients from Argentina.
BACKGROUND
Prolonged therapy with ganciclovir (GCV) can result in the development of GCV-resistant strains due to mutations in the viral phosphotransferase (UL97 gene) and/or in the viral DNA polymerase (UL54 gene).


OBJECTIVE
The purpose of this study was to detect by molecular methods the most prevalent UL97 mutants which confer ganciclovir-resistance in immunocompromised populations.


METHODS
Patients from two populations were selected: (a) renal transplant patients with active cytomegalovirus (CMV) infection and more than one cycle of GCV; (b) HIV-infected patients with retinitis due to CMV, who were under GCV induction, maintenance therapy or withdrawal. Patients were followed up by pp65 antigenemia and by viral isolation from blood or/and urine samples. Two fragments (133 and 255pb) of the UL97 gene were amplified by polymerase chain reaction (PCR) from CMV isolates.


RESULTS
Nine from 12 isolates obtained were sequenced, three from two renal transplant patients and six from five HIV-infected patients. A UL97 mutation, known to confer GCV resistance, was found in two isolates from a renal transplant patient. A methionine to valine mutation at codon 460 (M460V) was detected. These isolates exhibited another mutation at codon 605, whose amino acid changed from aspartic acid (D) to glutamic acid (E). These findings were observed after treatment with IV-GCV/ O-GCV/ IV-GCV for 151 days. The 605 mutation was also detected in leukocytes from the same patient previous to the beginning of the treatment with GCV.


CONCLUSIONS
Although a known resistant mutation appeared in a renal transplant patient, it was not associated with CMV disease. We suggest that the D605E mutation could "partially or totally compensate" for the effect of GCV resistance conferred by the 460 mutation. Further studies should be performed to confirm this hypothesis.
Sánchez Puch
Silvia
S
Clinical Virology Laboratory, CEMIC University Hospital, Galván 4102, C1431FWN Buenos Aires, Argentina. ssp@fibertel.com.ar
Ochoa
Claudia
C
Carballal
Guadalupe
G
Zala
Carlos
C
Cahn
Pedro
P
Brunet
Rosario
R
Salomón
Horacio
H
Videla
Cristina
C
D017088:AIDS-Related Opportunistic Infections / Q000821:virology; D000998:Antiviral Agents / Q000494:pharmacology*; D001118:Argentina; D003587:Cytomegalovirus / Q000187:drug effects*; D003586:Cytomegalovirus Infections / Q000175:diagnosis / Q000188:drug therapy / Q000821:virology; D017726:Cytomegalovirus Retinitis / Q000175:diagnosis / Q000188:drug therapy / Q000821:virology; D024882:Drug Resistance, Viral; D015774:Ganciclovir / Q000494:pharmacology*; D006801:Humans; D016867:Immunocompromised Host; D016030:Kidney Transplantation / Q000009:adverse effects; D008969:Molecular Sequence Data; D009154:Mutation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics*; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D000998:Antiviral Agents; D017853:Phosphotransferases (Alcohol Group Acceptor); C075365:ganciclovir kinase; D015774:Ganciclovir