USE OF QUANTITATIVE COMPETITIVE PCR TO MEASURE EPSTEIN-BARR-VIRUS GENOME LOAD IN THE PERIPHERAL-BLOOD OF PEDIATRIC TRANSPLANT PATIENTS WITHLYMPHOPROLIFERATIVE DISORDERS

A quantitative competitive PCR (QC-PCR) assay for Epstein-Barr virus ( EBV) has been developed to provide accurate measurement of EBV genome load in pediatric transplant recipients at risk for developing posttra nsplant lymphoproliferative disorder (PTLD). The assay quantifies betw een 8 and 5,000 copies of the EBV genome in 10(5) lymphocytes after a 30-cycle amplification reaction. For 14 pediatric patients diagnosed w ith PTLD, the median EBV genome load was 4,000, and 13 of the 14 patie nts had values of >500 copies per 10(5) lymphocytes. Only 3 of 12 cont rol transplant recipients not diagnosed with PTLD had detectable viral genome loads (median value, 40). This median was calculated by using the highest value obtained by PCR testing on each of these patients po sttransplantation. PCR values of >500 copies per 10(5) lymphocytes app ear to correlate with a diagnosis of PTLD. By a modified protocol, the EBV genome copy number in latently infected adults was estimated to b e <0.1 copy per 10(5) lymphocytes.