Comparison of 3 vaccination strategies against porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae, and porcine circovirus type 2 on a 3 pathogen challenge model

Abstract

The objective of this study was to compare clinical, microbiologic, immunologic, and pathologic parameters in pigs each concurrently administered porcine reproductive and respiratory syndrome virus (PRRSV), Mycoplasma hyopneumoniae, and porcine circovirus type 2 (PCV2) vaccine from 1 of 2 commercial sources at 21 days of age and challenged with field strains of each of the 3 pathogens. Pigs were challenged with PRRSV and M. hyopneumoniae at 42 days of age (-14 days post-challenge, dpc) followed by a challenge with PCV2 at 56 days of age (0 dpc). Significant differences were observed between vaccinated challenged and unvaccinated challenged groups in clinical (average daily gain and clinical signs), microbiologic (viremia and nasal shedding), immunologic (antibodies and interferon-γ secreting cells), and pathologic (lesions) outcomes. Significant differences were observed among the 3 vaccinated challenged groups in microbiologic (nasal shedding of M. hyopneumoniae and viremia of PCV2) and immunologic (M. hyopneumoniae- and PCV2-specific interferon-γ secreting cells) outcomes. The vaccination regimen for PRRSV vaccine, M. hyopneumoniae vaccine, and PCV2 vaccine is efficacious for controlling triple challenge with PRRSV, M. hyopneumoniae, and PCV2 from weaning to finishing period.

Figure 1

Clinical respiratory sign scores in the different groups: Zoetis-VacA/Ch ( ), Zoetis-VacB/Ch ( ), BI-Vac/Ch ( ), UnVac/Ch ( ), and UnVac/UnCh (⋄). Different letters within a sampling point mean statistically significant differences (P < 0.05).

Figure 2

Quantification of porcine reproductive and respiratory syndrome virus (PRRSV) RNA, Mycoplasma hyopneumoniae DNA, and porcine circovirus type 2 (PCV2) DNA. A — Mean values of the genomic copy numbers of PRRS RNA in the serum samples. B — Mean values of the genomic copy numbers of M. hyopneumoniae DNA in the nasal swabs, and C — Mean values of the genomic copy numbers of PCV2 DNA in the serum samples in the different groups: Zoetis-VacA/Ch ( ), Zoetis-VacB/Ch ( ), BI-Vac/Ch ( ), UnVac/Ch ( ), and UnVac/UnCh (⋄). Different letters within a sampling point mean statistically significant differences (P < 0.05).

Figure 3

Enzyme-linked immunosorbent assay. A — Mean values of the anti-porcine reproductive and respiratory syndrome virus (PRRSV) antibody levels. B — Mean values of the anti-Mycoplasma hyopneumoniae antibody levels. C — Mean values of the anti-porcine circovirus type 2 (PCV2) antibody levels in the different groups: Zoetis-VacA/Ch ( ), Zoetis-VacB/Ch ( ), BI-Vac/Ch ( ), UnVac/Ch ( ), and UnVac/UnCh (⋄). Different letters within a sampling point mean statistically significant differences (P < 0.05).

Figure 4

Frequency of interferon-γ secreting cells (IFN-γ-SC). A — Mean number of porcine reproductive and respiratory syndrome virus (PRRSV)-specific IFN-γ-SC. B — Mean number of Mycoplasma hyopneumoniae-specific IFN-γ-SC. C — Mean number of PCV2-specific IFN-γ-SC in the different groups: Zoetis-VacA/Ch ( ), Zoetis-VacB/Ch ( ), BI-Vac/Ch ( ), UnVac/Ch ( ), and UnVac/UnCh (⋄). Different letters within a sampling point mean statistically significant differences (P < 0.05).