A case of ganciclovir-resistant cytomegalovirus (CMV) retinitis in a patient with AIDS: longitudinal molecular analysis of the CMV viral load and viral mutations in blood compartments.

OBJECTIVE

To study the temporal relationships between cytomegalovirus (CMV) viral load and specific UL97 mutations in polymorphonuclear leukocytes (PMNL) and plasma samples from a patient with AIDS who developed ganciclovir-resistant CMV retinitis.

METHODS

Sequential PMNL and plasma samples were analysed for determination of the CMV viral load using non-molecular methods and a quantitative polymerase chain reaction (PCR) assay. Screening of the same samples for the most common mutations conferring ganciclovir resistance was performed using nested PCR and restriction enzyme analysis.

RESULTS

At the time of progression of CMV retinitis (after 6 months of ganciclovir), a rapid increase in the CMV DNA load was found in both PMNL and plasma samples. This increase paralleled the emergence of a specific mutation (V594) in the same samples and recovery of ganciclovir-resistant blood isolates. In this patient, however, the only tests that substantially predicted the progression of CMV disease were the quantitative PCR assay using PMNL and to a lesser extent the pp65 antigenemia assay.

CONCLUSIONS

Quantitative evaluation of the CMV viral load in PMNL using sensitive assays such as PCR appears to be a promising approach for monitoring antiviral therapy in subjects with AIDS. In addition, common mutations conferring ganciclovir resistance can be detected directly in PMNL and plasma samples.