Development of new cytomegalovirus UL97 and DNA polymerase mutations conferring drug resistance after valganciclovir therapy in allogeneic stem cell recipients.
BACKGROUND
We report on two allogeneic stem cell transplant recipients who developed cytomegalovirus disease associated with new viral mutations that conferred antiviral drug resistance.


METHODS
Blood specimens obtained during symptomatic disease were analyzed for mutations in the CMV UL97 and DNA polymerase genes and new mutations were assessed by recombinant phenotyping.


RESULTS
Rising cytomegalovirus (CMV) antigenemia occurred after 4-5 months of preemptive valganciclovir therapy, followed by symptomatic CMV disease including fatal pneumonia in one case. In one case, a new viral UL97 mutation (deletion of codons 601-603) was found which conferred 15-fold increased ganciclovir resistance. In the other case, a known UL97 resistance mutation M460V and a new DNA polymerase (pol) mutation D413A were found. D413A conferred ganciclovir and cidofovir resistance.


CONCLUSIONS
Known and newly discovered drug resistance mutations arising during preemptive therapy may complicate post-transplant CMV disease in stem cell recipients. Improved recombinant phenotyping methods enable the rapid quantitation of the resistance conferred by newly identified UL97 and pol mutations.
Marfori
Jennifer E
JE
Medical and Research Services, VA Medical Center and Oregon Health and Science University, Portland, OR, USA.
Exner
Maurice M
MM
Marousek
Gail I
GI
Chou
Sunwen
S
Drew
W Lawrence
WL
D000998:Antiviral Agents / Q000627:therapeutic use*; D003587:Cytomegalovirus / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D003586:Cytomegalovirus Infections / Q000188:drug therapy / Q000517:prevention & control / Q000821:virology*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D024882:Drug Resistance, Viral / Q000235:genetics*; D005260:Female; D015774:Ganciclovir / Q000031:analogs & derivatives* / Q000627:therapeutic use; D006801:Humans; D008875:Middle Aged; D009154:Mutation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics*; D033581:Stem Cell Transplantation; D014184:Transplantation, Homologous; D000077562:Valganciclovir
D000998:Antiviral Agents; D017853:Phosphotransferases (Alcohol Group Acceptor); C075365:ganciclovir kinase; D004259:DNA-Directed DNA Polymerase; D000077562:Valganciclovir; D015774:Ganciclovir