Quantification of Active and Latent Form of Human Cytomegalovirus Infection in Umbilical Cord Blood Donors by Real-Time PCR

Background: Umbilical cord blood (UCB) is believed to be a highly valuable source of hematopoietic stem cells for transplantation. Objective: To investigate the prevalence of active and latent human cytomegalovirus (CMV) infection in UCB donors in Iranian population.

Methods: A total of 825 UCB samples was collected under standard procedures and analyzed for the presence of CMV DNAs in buffy coat (latent infection) and plasma (active infection). DNA was extracted from buffy coat and plasma samples separately and tested with quantitative real-time PCR. All positive samples were checked by ELISA for IgG and IgM anti-CMV antibody.

Results: Latent CMV infection was detected in 17 (2%) buffy coat samples with a low level of viral load, which indicated the presence of latent viral infection in donors. None of the plasma samples were found positive for CMV DNA reflecting no active infection. In the 17 positive samples, CMV viral load was 91-104 (mean: 100) copies/mL. All samples positive for viral DNA were also found positive for CMV IgG antibody by ELISA. No CMV IgM antibody was detected in positive samples.

Conclusion: CMV is still the most important virus that infects hematopoietic stem cells and could be dangerous, especially for immunocompromized transplant recipients. We therefore suggest using real-time PCR for the detection and quantification of the viral DNA in buffy coat and plasma of UCB donors. PCR of plasma for detection of CMV and antibody assay for CMV infection add no more sensitivity for the detection of latent CMV infection in UCB donors.