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Bulletin No. 20 - Winter 2004
VirologyPMWS-PCV2-PCVD-PDNS
OPRIESSNIG T, YU S, THACKER EL, HALBUR PG
Derivation of porcine circovirus type 2-negative pigs from positive breeding herds.
J Swine Health Prod, Vol. 12, Nº4, 2004, 186-191
A serological screening was carried out in dams in 6 US breeding herds free of PMWS. Samples were collected 7-10 days or 5 months prior to farrowing. PCV2-specific antibody levels were evaluated using an ELISA based on ORF2 capsid protein. Following segregated early weaning (SEW) at 10 or 12 days of age, piglets were raised in isolation facilities until 15 weeks of age. Sera were tested weekly for the presence of maternal PCV2 antibodies by ELISA and indirect immunofluorescence assay and for the absence of PCV2 by PCR. In addition, PCR and immunohistochemistry assays were performed on lymphoid tissue samples collected at necropsy. It was shown that higher PCV2 ELISA S:P ratios at weaning took more time to decline below the positive cutoff value. Interestingly, by the end of the study all pigs were still free of PCV2 antigen and nucleic acids indicating that derivation of PCV2-negative piglets from positive breeding herds may be possible through SEW.
