Human cytomegalovirus load in the peripheral blood determined by quantitative competitive polymerase chain reaction.

Primary human cytomegalovirus infection and the viral reactivation from latency are major complications in organ transplant recipients. In the peripheral blood the replicating virus can be detected either by nucleic acid based tests or by demonstrating the HCMV structural proteins in antigenemia test. We developed a quantitative competitive PCR method to assess the HCMV load in the peripheral blood. The viral load in nine healthy blood donors and in four renal transplant recipients with negative antigenemia test was in the same range: 5-124 (median: 18) HCMV copies/10(6) beta-globin copies for healthy blood donors and 16-48 (median: 37) HCMV copies/10(6) beta-globin copies for the transplant recipients. Three antigenemia positive renal transplant recipients had a HCMV load of 2.2 x 10(5)/10(6) beta-globin, 1.5 x 10(4)/10(6) beta-globin and 6.5 x 10(3)/10(6) beta-globin, respectively. In conclusion, the quantitative measurement of HCMV load in the peripheral blood correlated well with the routine HCMV antigenemia test. The DNA-based test, however can detect earlier the reactivation of the HCMV infection.