title: The utility of plasma polymerase chain reaction for human herpes virus-6 among pediatric bone marrow transplant recipients: results of a pilot study.
abstract: We evaluated the utility of plasma polymerase chain reaction (PCR) for surveillance of human herpes virus 6 (HHV-6) infection among pediatric bone marrow transplant (BMT) recipients. We used a prospective, non-interventional design involving a study group and controls. BMT recipients and healthy controls were evaluated. BMT subjects had HHV-6 PCR done biweekly for 12 weeks post transplantation, while a single PCR test was done on controls. For the PCR assay, EDTA blood was collected and DNA extracted from whole blood and cell-free plasma using standard procedures. The PCR was first performed on DNA from whole blood and if a positive result was obtained, the test was repeated on the DNA from the plasma. Thirty BMT recipients (13 autologous and 17 allogeneic) were enrolled, on whom a total of 156 PCR tests were performed, while six tests were done on six healthy controls. The median age of BMT subjects was 6.2 years (range 0.5-17.5 years). The median age of the control subjects was 6.6 years (range 2-10 years). Among asymptomatic BMT patients who had PCR surveillance, the positivity rate was 3.3% (1/30) on whole blood and 0% (0/30) on plasma. None of the six healthy subjects had a positive PCR test on whole blood. During the period of the surveillance study, 14 patients had diagnostic evaluations for HHV-6 disease because of clinical symptoms. Two of these patients were diagnosed with disease associated with HHV-6 (graft failure and encephalitis) and had positive PCR tests on whole blood and plasma and whole blood and cerebrospinal fluid, respectively. We conclude that despite the fact that HHV-6 seropositivity rates are high among children, the frequency of HHV-6 plasma PCR positivity is low in pediatric BMT subjects who are asymptomatic for HHV-6 disease. Given that a positive test on plasma is consistent with active infection, this increases the utility of the PCR test as a diagnostic aid in evaluating syndromes presumed to be due to HHV-6 in pediatric bone marrow transplant recipients.
authors.affiliation: The Department of Pediatrics, Division of Infectious Diseases, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada.
authors.forename: U D
authors.initials: UD
authors.lastname: Allen
authors.forename: R
authors.initials: R
authors.lastname: Tellier
authors.forename: J
authors.initials: J
authors.lastname: Doyle
authors.forename: M
authors.initials: M
authors.lastname: Petric
authors.forename: S
authors.initials: S
authors.lastname: Wasfy
authors.forename: P
authors.initials: P
authors.lastname: Kumar
authors.forename: S
authors.initials: S
authors.lastname: Calderwood
authors.forename: M
authors.initials: M
authors.lastname: Freedman
authors.forename: F
authors.initials: F
authors.lastname: Saunders
mesh_terms: D000293:Adolescent; D016026:Bone Marrow Transplantation / Q000009:adverse effects; D002648:Child; D002675:Child, Preschool; D004279:DNA, Viral / Q000097:blood*; D005260:Female; D015654:Herpesvirus 6, Human / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D007223:Infant; D008297:Male; D010865:Pilot Projects; D016133:Polymerase Chain Reaction / Q000379:methods*; D011446:Prospective Studies; D019349:Roseolovirus Infections / Q000097:blood / Q000235:genetics*
chemical_list: D004279:DNA, Viral