Monitoring of human cytomegalovirus infection in immunosuppressed patients using real-time PCR on whole blood.

Background: Quantitative monitoring of human cytomegalovirus (HCMV) is currently used in the follow-up of immunosuppressed patients.

Objective: To investigate whether real-time PCR quantification (QPCR) of HCMV DNA could replace pp65 antigenemia.

Study Design: We compared HCMV QPCR on whole blood (WB) and on plasma with a pp65-antigenemia assay on 192 samples. Afterwards, we tested 1310 samples from 308 immunosuppressed patients both by antigenemia assay and QPCR on WB.

Results: The first study comparison showed that QPCR results on WB and plasma were significantly correlated with antigenemia. QPCR on WB was more sensitive than QPCR on plasma or antigenemia, detecting 31 and 49 additional positive samples, respectively. During the second comparison, QPCR on WB and antigenemia were again correlated (r=0.70; p<0.0001), but QPCR detected 244 additional positive samples. HCMV DNA was detected earlier than pp65 antigen (median difference: 14 days; range: 7-30). One, 5, 10, 50 and 100 pp65-positive cells/200,000 leukocytes corresponded to 439, 1531, 2623, 9150 and 15,671 HCMV DNA copies/mL of WB, respectively, but this equivalence differed according to the sub-group of patients considered.

Conclusion: QPCR on WB is the most sensitive method for the monitoring of HCMV infection in immunosuppressed patients.