Background: The Real-time PCR assay has been established as the standard method for Human Cytomegalovirus (HCMV) quantitation in immunocompromised patients. However, the question of which one of whole blood or plasma specimens is better for viral quantitation is still unresolved for many clinical laboratories. To answer this question, the current study compares HCMV DNA load in whole blood and plasma samples.

Materials and Methods: In this prospective study, the whole blood and plasma samples were obtained from 41 transplantated patients and the viral load was detected using a validated, in-house Real-time PCR assay.

Results: Of the total 193 examined specimens, 174 were negative and 19 samples, from 16 patients, were positive in at least one of whole blood or plasma samples. Based on the results of linear regression analysis, the cytomegalovirus viral load was correlated in whole blood and plasma samples (R2: 0.872). However, the regression equation shows that the HCMV load in whole blood samples is higher than load of this virus in plasma. The validity of the quantitative results was confirmed by repeating the tests and analyzing the results using the repeated measure analysis.

Conclusion: Based on the results of the present study, HCMV quantitation in whole blood samples has a higher analytical sensitivity than in plasma samples.