Early selection of a new UL97 mutant with a severe defect of ganciclovir phosphorylation after valaciclovir prophylaxis and short-term ganciclovir therapy in a renal transplant recipient.

We describe the emergence of a new ganciclovir resistance mutation in the UL97 gene of human cytomegalovirus, deletion of codon 601, after valaciclovir and short-term ganciclovir therapy following kidney transplantation. Its role in ganciclovir resistance was supported by decreased ganciclovir phosphorylation in a recombinant vaccinia virus system.