title: A semiquantitative PCR method (SQ-PCR) to measure Epstein-Barr virus (EBV) load: its application in transplant patients.
abstract: BACKGROUND
  High Epstein-Barr virus load has been related to an increased risk of Posttransplant Lymphoproliferative Disorders (PTLD) in transplant recipients.
  
  
  OBJECTIVE
  Development of a method to quantitate EBV DNA levels in peripheral blood mononuclear cells (PBMC) and evaluate its usefulness in transplant patients.
  
  
  METHODS
  We designed a semiquantitative nested PCR based on a limiting dilution analysis to detect high viral loads in PBMC. This method was applied to 25 healthy carriers, and 85 solid organ transplant recipients as follows: (A) 53 asymptomatic patients; (B) 24 symptomatic patients; (C) eight patients with PTLD.
  
  
  RESULTS
  In healthy carriers the reciprocal of the limiting dilution (RLD) ranged between non-detected (ND) and 1, the median RLD was ND, which is equivalent to a viral load of <1 copy per 10(5) PBMC. In the transplant population the medians RLD (range) were: (A) asymptomatic group: ND (ND-64), median equivalent to a viral load of <1 copy per 10(5) PBMC; (B) symptomatic group: 4 (ND-256), median equivalent to a range of viral load of 4-64 copies per 10(5) PBMC. (C) PTLD group: 256 (16-16384), median equivalent to a range of viral load of 256-4096 copies per 10(5) PBMC. Statistically significant differences were found between all groups: A+B vs. C (P<0.0001); A vs. B (P<0.0001); A vs. C (P<0.0001), B vs. C (P<0.0001). We also observed a good correlation between viral loads and clinical findings in four follow-up patients. Considering the RLD=256 as a cutoff point to detect transplant patients with PTLD, resulted in sensitivity 75%, specificity 96.7%, positive predictive value 60%, negative predictive value 98.3%.
  
  
  CONCLUSIONS
  This SQ-PCR method enables us to differentiate between transplant patients with and without PTLD; therefore, it could be applied as a marker for early detection of this pathology.
authors.affiliation: Servicio Virus Oncogénicos, Instituto Nacional de Enfermedades Infecciosas-ANLIS, Buenos Aires, Argentina. oncovir@sudnet.com.ar
authors.forename: María Dolores
authors.initials: MD
authors.lastname: Fellner
authors.forename: Karina
authors.initials: K
authors.lastname: Durand
authors.forename: Mariel
authors.initials: M
authors.lastname: Correa
authors.forename: David
authors.initials: D
authors.lastname: Bes
authors.forename: Lidia V
authors.initials: LV
authors.lastname: Alonio
authors.forename: Angélica R
authors.initials: AR
authors.lastname: Teyssié
authors.forename: María Alejandra
authors.initials: MA
authors.lastname: Picconi
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004279:DNA, Viral / Q000097:blood; D004854:Herpesvirus 4, Human / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D016030:Kidney Transplantation / Q000009:adverse effects*; D007963:Leukocytes, Mononuclear / Q000821:virology; D016031:Liver Transplantation / Q000009:adverse effects*; D008232:Lymphoproliferative Disorders; D016133:Polymerase Chain Reaction / Q000379:methods*; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D019562:Viral Load
chemical_list: D004279:DNA, Viral