A commercial porcince circovirus (PCV) type 2a- based vaccine reduces PCV2d viremia and shedding and prevents PCV2d transmission to naïve pigs under experimental conditions.

Porcine circovirus type 2 (PCV2) vaccination has been effective in protecting pigs from clinical disease and today is used extensively. Recent studies in vaccinated populations indicate a major PCV2 genotype shift from the predominant PCV2 genotype 2b towards 2d.
calendar icon 31 August 2017
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Tanja Opriessnig et al. 2016

Aim: The aims of this study were to determine the ability of the commercial inactivated PCV2a vaccine Circovac to protect pigs against experimental challenge with a 2013 PCV2d strain and prevent transmission.

Method: 38 pigs were randomly divided into four groups with 9-10 pigs per group: NEG (sham-vaccinated, sham-challenged), VAC (PCV2a-vaccinated, sham-challenged). Vaccinated was done at 3 weeks of age using Circovac according to label instructions. The CHAL and VAC + CHAL groups were challenged with PCV2d at 7 weeks of age and all pigs were vaccination (dvp).

Results: At PCV2d challenge on 28 dpv, 3/9 VAC and 1/9 VAC and 1/9 VAC CHAL pigs were seropositive. NEG pigs remained seronegative for the duration of the study. Vaccination significantly reduced PCV2d viremia (VAC + CHAL) at dpc 14 and 21, PCV2d faecal shedding at dpc 14 and 21 and PCV2d nasal shedding at dpc 7, 14 and 21 compared to CHAL pigs.

When pooled serum or faeces collected from VAC + CHAL and CHAL pigs at dpc 21 were used to expose single-housed PCV2 naïve pigs, a pooled faecel sample from CHAL pigs contained infectious PCV2 whereas this was not the case for VAC + CHAL pigs suggesting reduction of PCVd transmission by vaccination.

Conclusion: Under the study conditions, the PCV2a-based vaccine was effective in reducing PCV2d virmia, tissue loads, shedding and transmission indicating that PCV2a vaccination should be effective in PCV2d-infected herds.

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