Porcine circovirus type 2 (PCV2) is associated with reproductive failure in pregnant female pigs; however, the role of PCV2 in semen has not been elucidated. To determine the significance of semen in vertical PCV2 transmission, a two phased experiment was designed. The goal of the experimental investigation was to determine if semen contaminated with PCV2 has the ability to result in sow or fetal infection when delivered via artificial insemination. The second goal was to determine if PCV2 antibodies (vaccine or previous infection) can reduce or block sow or fetal infection via artificial insemination.
In the first phase, PCV2 negative sows were divided into 3 groups of 3. Sows were 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 became infected following insemination. No group 2 sows showed signs of pregnancy after insemination while all group 3 sows (3/3) farrowed at the expected date. At farrowing, pre-suckle serum samples were collected from live-born piglets and all piglets (live-born, stillborn, and mummified fetuses) were necropsied for tissue examination. All live-born piglets in group 3 were PCV2 viremic at birth, stillborn fetuses had gross lesions of congestive heart failure, and mummified fetuses varied in crown-rump length indicating fetal death at different stages of gestation. PCV2 was detected in the myocardium by immunohistochemistry (IHC) in 88% live-born piglets and all stillborn and mummified fetuses. Results of phase I indicate that intrauterine administration of PCV2 can cause reproductive failure and fetal infection in naïve sows when delivered by artificial insemination.
In phase II, nine sows were divided into 3 groups: Group 1 (n = 3) dams were PCV2 naïve and were artificially inseminated with extended PCV2 DNA negative semen during estrus. PCV2 naïve dams, Group 2 (n = 3) and Group 3 (n = 3) were vaccinated with a commercially available PCV2 vaccine or infected with PCV2 months prior to artificially insemination with PCV2 spiked semen, respectively. All group 2 and 3 dams were antibody positive and non-viremic at insemination. Eight of nine dams became pregnant and carried pregnancy to term with one group 2 dam and two group 3 dams-having detectable viremia during gestation. In group 2, 15/24 live-born piglets were PCV2 viremic at birth with 6 fetuses having detectable PCV2 antigen in tissue. Results of phase II indicate that previous dam infection, but not vaccine induced antibodies were protective against fetal infection in the PCV2 model using spiked semen.
Contact Information: [email protected]
