PCV2 infection in vaccinated conventional gilts inseminated with PCV2b-spiked semen

The present trial investigated the effect of PCV2 vaccination on viremia, virus shedding and viral load in maternal tissues and foetuses of conventional gilts inseminated with PCV2b-spiked semen. Twelve gilts were randomly divided into two groups of six animals each (vaccinated infected, VI; non-vaccinated infected, NVI). Estrus synchronization was followed by artificial insemination (AI) with a single PCV2 negative semen dose supplemented with 0.2 mL of a PCV2b suspension containing 104.4 TCID50/50 μL (total viral dose: 105 TCID50). Vaginal, nasal and faecal swabs, and blood samples were collected weekly from two days before artificial insemination till the end of the experimental period (55 days post AI; DPAI) and tested by real-time PCR (qPCR) for PCV2; sera were tested for anti- PCV2 antibodies. During necropsy foetal and maternal tissues were collected for qPCR and histopathology. In each of the VI and NVI groups three out of the six gilts were pregnant at 29 DPAI. The VI group showed a significantly lower proportion of PCR-positive swabs: 24.6% VI vs 71.3% NVI. PCV2 clearance was demonstrated by qPCR in lymphoid tissue during the trial in the VI group. Only one foetus was PCV2-positive (in the NVI group) and three amniotic fluids of the NVI group. PCV2 was found in a significantly lower proportion of the placenta of foetuses in the VI group (39%) than the NVI group (77%). The PCV2 vaccine seems to play an active role in reducing virus shedding, tissue viral load and foetoplacental infection.