The development of a beacon-based real-time PCR for cytomegalovirus and its application in immunocompromised patients.

Background: Because of the high cost of commercially available quantitative PCR kits, we developed a beacon- based real-time PCR (B-rt-PCR) for Cytomegalovirus (CMV) viral load determination.

Methods: A total of 197 samples from 60 immunocompromised patients, who were bone marrow transplantation recipients or had hematological malignancies, were tested using B-rt-PCR, COBAS Amplicor CMV Monitor test (Amplicor CMV test), and conventional CMV PCR. The correlation results among these 3 assays were calculated.

Results: In these 197 samples, the CMV viral load determined by B-rt-PCR for positive specimens ranged from 19.8 to 4148.7 copies/10(5) peripheral blood mononuclear cells (PBMCs). When any positive result of B-rt-PCR, the Amplicor CMV test, or conventional PCR was considered as "CMV positive" for the 56 specimens tested by all three methods, we found that the positive and negative predictive values, respectively, were 100% and 98.6% for B-rt-PCR, 100% and 46.2% for the Amplicor CMV test, and 100% and 89.4% for conventional PCR. These three methods had good specificity (all 100%). However, the sensitivity rate of B-rt-PCR (96.3%) was higher compared to the Amplicor CMV test (46.2%) and conventional PCR (89.4%).

Conclusions: The B-rt-PCR is evaluated to be a sensitive method for CMV detection in immunocompromised patients.