Diagnosis and Monitoring of Human Cytomegalovirus Infection in Bone Marrow Transplant Recipients by Quantitative Competitive PCR

Abstract

Objectives: Human cytomegalovirus (HCMV) is a common cause of infection worldwide. Severe cytomegalovirus disease is usually observed in immunodeficient individuals such as bone marrow transplant (BMT) or AIDS patients. In these patients, proof of viral presence is not enough for making clinical decisions; one must report the quantity of virus or viral load in appropriate clinical specimens to demonstrate the relationship between disease severity and HCMV infection. The goal of this study was to use quantitative competitive polymerase chain reaction (PCR) to determine HCMV viral load in 26 BMT recipients.

Materials and Methods: Peripheral blood was collected weekly for 100 days from 26 BMT recipients. Qualitative and quantitative competitive PCRs on 105 mononuclear cells were performed for each patient. The same tests were performed once for each of 26 donors. In addition, the anti-HCMV humoral response was detected by performing IgM and IgG ELISAs in donors and recipients prior to transplantation.

Results: Of 26 BMT donors and recipients, 25 and 26 were IgG positive, and 2 and 6 had HCMV-specific IgM antibodies, respectively. From 313 total clinical specimens tested, 255 had positive qualitative PCR results. Results of quantitative PCR on the same specimens demonstrated that in 14 patients, viral copy number per 105 cells had increased, pointing toward HCMV reactivation. In others, changes in viral copy number were mostly around 100/105 cells, with an upper limit of 300/105 cells.

Conclusions: Owing to the high prevalence of cytomegalovirus in our country, the chance of viral reactivation and HCMV infection/disease upon transplantation must be seriously considered. Therefore, use of quantitative PCR in PCR-positive patients is highly recommended to demonstrate active infection that may lead to HCMV disease during the posttransplant period. This also could help physicians begin pre-emptive therapy that would be for a shorter treatment period and provide for better outcomes in infected BMT patients.