EMERGENCE AND PREVALENCE OF CYTOMEGALOVIRUS UL97 MUTATIONS ASSOCIATEDWITH GANCICLOVIR RESISTANCE IN AIDS PATIENTS

Objectives: To evaluate the prevalence of the most common cytomegalovi rus (CMV) UL97 mutations associated with ganciclovir resistance direct ly in polymorphonuclear leukocytes (PMNL) of patients with AIDS and CM V retinitis. Also to correlate the presence (or absence) of these muta tions with the systemic CMV viral load and the ophthalmologic outcome of these subjects. Methods: Monthly blood samples were obtained from 1 9 patients with AIDS and CMV retinitis who had been treated with syste mic ganciclovir for greater than or equal to 2 months. Detection of CM V UL97 mutations was done using nested PCR amplification followed by r estriction enzyme analysis. The viral load was assessed with a polymer ase chain reaction-based assay and non-isotopic hybridization detectio n. Results: CMV UL97 mutations were detected in PMNL of four of 13 (30 .8%) patients who had been treated with ganciclovir for greater than o r equal to 3 months but in none of six patients who had been treated f or < 3 months. All four patients with detectable UL97 mutations were p resenting evidence of retinitis progression at the time those mutation s were first detected (mean, 145.7 days of ganciclovir) and three of f our patients had a viral DNA load > 10 000 copies per 10(5) PMNL contr asting with the copy numbers in the 15 subjects without mutations (mea n, 492.9 copies per 10(5) PMNL after a mean of 146.8 days of ganciclov ir). Conclusions: The prevalence of the most common CMV UL97 mutations associated with ganciclovir resistance in PMNL of patients with AIDS treated for greater than or equal to 3 months (30.8%) appears to be hi gher than the rate of emergence of ganciclovir-resistant CMV isolates as previously reported using phenotypic assays (about 8%). Moreover, t he detection of these mutations is associated with a considerable incr ease in the CMV DNA load in the blood as well as with progression of C MV retinitis during ganciclovir therapy.