WESTPORT, CT (Reuters Health) Jan 25 - A newly developed, highly sensitive quantitative PCR assay detects cytomegalovirus DNA before symptoms develop in hematopoietic stem-cell transplant (HSCT) recipients, according to a report in the February 1st issue of the Journal of Infectious Diseases.
Though at least 1% of HSCT recipients develop CMV disease, it is detected only at autopsy in more than half of affected patients, the researchers note. Early diagnosis and treatment might help to reduce the >90% mortality rate of pre-engraftment CMV disease.
Dr. Ajit P. Limaye, from the University of Washington in Seattle, and colleagues used the new assay to measure CMV DNA levels in the plasma of 15 HSCT recipients with pre-engraftment CMV disease (case patients) and 33 similar HSCT recipients who had not developed CMV disease.
The assay detected CMV DNA in 14 of 15 case patients before or at the onset of CMV disease, the authors report, compared with only 5 of the 33 control patients. Most of the case patients had positive test results at least 2 days before CMV disease onset, whereas only one of the control patients had positive results on more than one occasion during pre-engraftment.
The maximum CMV virus load among case patients was at least 10-fold that among control patients, the researchers determined, and most case patients (9/14) had more than 1000 copies/mL of CMV DNA prior to the onset of disease.
The negative predictive value of the CMV PCR assay was 99%, the report indicates, and the positive predictive value ranged from 27% (for HLA-mismatched related and matched unrelated transplants) to 43% (for CD34-selected autograft recipients).
In comments to Reuters Health, Dr. Limaye said that "when newer, less toxic antiviral agents become available, a preemptive approach initiating therapy guided by results of the plasma CMV PCR may help to reduce the incidence of pre-engraftment CMV disease among stem cell transplant recipients."
"The primers and probes, the details of which we have published, can be ordered commercially and adapted by clinical laboratories that have expertise using PCR technology," Dr. Limaye added.
J Infect Dis 2001;183:377-382.
2000 Reuters Ltd.