title: Identification of serum proteomic biomarkers for early porcine reproductive and respiratory syndrome (PRRS) infection.
abstract: BACKGROUND
  Porcine reproductive and respiratory syndrome (PRRS) is one of the most significant swine diseases worldwide. Despite its relevance, serum biomarkers associated with early-onset viral infection, when clinical signs are not detectable and the disease is characterized by a weak anti-viral response and persistent infection, have not yet been identified. Surface-enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF MS) is a reproducible, accurate, and simple method for the identification of biomarker proteins related to disease in serum. This work describes the SELDI-TOF MS analyses of sera of 60 PRRSV-positive and 60 PRRSV-negative, as measured by PCR, asymptomatic Large White piglets at weaning. Sera with comparable and low content of hemoglobin (< 4.52 μg/mL) were fractionated in 6 different fractions by anion-exchange chromatography and protein profiles in the mass range 1-200 kDa were obtained with the CM10, IMAC30, and H50 surfaces.
  
  
  RESULTS
  A total of 200 significant peaks (p < 0.05) were identified in the initial discovery phase of the study and 47 of them were confirmed in the validation phase. The majority of peaks (42) were up-regulated in PRRSV-positive piglets, while 5 were down-regulated. A panel of 14 discriminatory peaks identified in fraction 1 (pH = 9), on the surface CM10, and acquired at low focus mass provided a serum protein profile diagnostic pattern that enabled to discriminate between PRRSV-positive and -negative piglets with a sensitivity and specificity of 77% and 73%, respectively.
  
  
  CONCLUSIONS
  SELDI-TOF MS profiling of sera from PRRSV-positive and PRRSV-negative asymptomatic piglets provided a proteomic signature with large scale diagnostic potential for early identification of PRRSV infection in weaning piglets. Furthermore, SELDI-TOF protein markers represent a refined phenotype of PRRSV infection that might be useful for whole genome association studies.
authors.affiliation: Parco Tecnologico Padano - CERSA, Via Einstein, 26900, Lodi, Italy. geninis@vet.upenn.edu.
authors.forename: Sem
authors.initials: S
authors.lastname: Genini
authors.forename: Thomas
authors.initials: T
authors.lastname: Paternoster
authors.forename: Alessia
authors.initials: A
authors.lastname: Costa
authors.forename: Sara
authors.initials: S
authors.lastname: Botti
authors.forename: Mario Vittorio
authors.initials: MV
authors.lastname: Luini
authors.forename: Andrea
authors.initials: A
authors.lastname: Caprera
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Giuffra