Birth abnormalities in pregnant sows infected intranasally with porcine circovirus 2.

Six pregnant sows were inoculated intranasally at 3 weeks before the expected farrowing date with porcine circovirus 2 (PCV2). The PCV2-inoculated sows showed abortion and premature farrowing, whereas two uninfected negative control sows remained clinically healthy and farrowed normally. PCV2 antigen and DNA were detected by immunohistochemistry and in-situ hybridization, respectively, in lymph node, spleen, thymus, lung, tonsil and liver from both stillborn and liveborn piglets. Simultaneous detection of viral protein and DNA provided molecular evidence of PCV2 infection and replication. The experiment suggested that PCV2 is capable of crossing the placenta, replicating primarily in lymphoid tissues, and inducing reproductive failure.