Session: Poster Session: Herpes Viruses
Monday, October 27, 2008: 12:00 AM
Room: Hall C
Background: Cytomegalovirus (CMV) load monitoring in peripheral blood is an essential step in the follow up of severely immunodepressed patients, as are the receivers of a bone marrow or solid organ transplant. Molecular methods can be competitive with the traditional pp65 antigen assay. Accuracy of a quantitative real-time PCR TaqMan procedure (r-tPCR) on whole blood was compared to pp65 antigen detection by immunofluorescence (pp65). Methods: 832 blood samples from patients in early post-transplant period were included in the study. Both method were executed on each sample. Categorical accuracy indexes were calculated. The quantitative equivalence between the two methods was examined by means of a nonlinear regression model. Results: Prevalence with r-tPCR: 30%, prevalence with pp65: 21%; concordance: 88%, kappa: 70%. R-tPCR showed sensitivity: 93%, specificity: 87%. The final quantitative model (logCMVDNA = b1*b2^logpp65; R-squared = 0.9390) is shown in the figure. Conclusions: The direct assay on whole blood simplified the sample manipulation avoiding problems due to partial and erratic recovery. The relationship between r-tPCR assay on whole blood and pp65 was highly significant a log-log scale. An equivalence table between the two procedures was obtained. Moreover, the r-tPCR appeared more sensitive than pp65.