Detection of Porcine circovirus type 2 viremia and seroconversion in naturally infected pigs in a farrow-to-finish barn.
Porcine serum was assayed by 2 polymerase chain reaction (PCR) protocols (nested PCR [nPCR] and non-nested PCR) and a competitive enzyme-linked immunosorbent assay to determine when Porcine circovirus type 2 (PCV2) viremia and a rise in the serum level of PCV2-specific antibody occurred in pigs raised in a large Canadian farrow-to-finish barn. Eight serial blood samples were collected from each of 40 pigs from 5 to 156 (+/- 1.5) d of age; 6 pigs were removed from the study for various reasons at various times. Viremia was not detected in the samples collected before 72 d of age but was detected in those collected on or after 72 d: of 33 pigs, 7 (21%) had only 1 serum sample positive for PCV2 DNA by nPCR after day 72; 11 (33%) were intermittently positive by nPCR, non-nested PCR, or both between 72 and 156 d; and the remaining 15 (45%) were repeatedly positive (in 2 to 4 samples). The level of serum antibody against PCV2 declined after weaning and increased between 72 and 107 d of age, only after PCV2 was detected in serum. Our results show that PCV2 viremia persists in the presence of elevated levels of PCV2-specific antibody.
McIntosh
Kathleen A
KA
Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4. kathy.mcintosh@usask.ca
Harding
John C S
JC
Ellis
John A
JA
Appleyard
Greg D
GD
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D000914:Antibodies, Viral / Q000097:blood*; D018173:Circoviridae Infections / Q000175:diagnosis / Q000662:veterinary*; D017925:Circovirus / Q000302:isolation & purification*; D004279:DNA, Viral / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D016133:Polymerase Chain Reaction / Q000662:veterinary; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis*; D014766:Viremia / Q000175:diagnosis / Q000662:veterinary; D014886:Weaning
D000914:Antibodies, Viral; D004279:DNA, Viral