Reproductive failure experimentally induced in sows via artificial insemination with semen spiked with porcine circovirus type 2

Abstract

Porcine circovirus type 2 (PCV2) is associated with reproductive failure in female pigs. However, the association of PCV2-positive semen in the pathogenesis has not been elucidated. The objectives of this study were to determine whether semen spiked with PCV2 causes infection in PCV2-näive, mature female pigs and whether delivery of PCV2 via artificial insemination causes reproductive failure or fetal infection. Nine sows were randomly allocated into 3 groups of 3 sows each and artificially inseminated with PCV2 DNA-negative semen (group 1), PCV2 DNA - negative semen spiked with PCV2a (group 2), or PCV2b (group 3). All sows in groups 2 and 3 developed PCV2 viremia 7 to 14 days after insemination. None of the group 2 sows became pregnant, whereas all group 3 sows (3/3) farrowed at the expected date. At parturition, presuckle serum samples were collected, and live-born piglets, stillborn fetuses, and mummified fetuses were necropsied. All live-born piglets (n 5 8) in group 3 were PCV2 viremic at birth. Stillborn fetuses (n 5 2) had gross lesions of congestive heart failure. Mummified fetuses (n 5 25) varied in crown-rump length from 7 to 27 cm, indicating fetal death between 42 and 105 days of gestation. PCV2 antigen was detected in the myocardium by immunohistochemistry of 7/8 (88%) live-born piglets, 2/2 (100%) of the stillborn fetuses, and 25/25 (100%) of the mummified fetuses. In addition, 4/25 mummified fetuses had PCV2 antigen associated with smooth muscle cells and fibroblasts. The results of this study indicate that intrauterine administration of PCV2 causes reproductive failure in näive sows.