Identification of an immunorelevant ORF2 epitope from porcine circovirus type 2 as a serological marker for experimental and natural infection

Post-weaning multisystemic wasting syndrome (PMWS) is a recently identified disease of pigs linked to the emergence of a new porcine circovirus (PCV2) . We report here the characterization of immunorelevant linear B-ci:ll epit opes of the Open Reading Frame 2-encoded protein (Orf2) from PCV2 by an enz yme-linked immunosorbent assay (ELISA) using experimental antisera collecte d from pigs inoculated with a PCV2 isolate. Two epitopes spanning residues 69 to 83 and 117 to 131 were specific to PCV2. Antibodies to the 117 to 131 epitope (B-133) were detected in 22% and 100% of specific pathogen-free (S PF) pig sera 6 and 11 weeks post inoculation, respectively. Cross-sectional studies performed with field sera collected from PMWS-affected herds showe d B-133 antibodies in 5% of 8 to 10 week-old pigs, 38% of 13-14 week-old pi gs, 62% of 16 to 19 week-old pi,os, 56% of 20 to 25 week-old pigs and 45% o f 26 to 31 week-old pigs. All these data suggest that epitope B-133 is a se rological marker of PCV2 infection that could be used for the detection of PCV2 antibody response.