Efficacy comparison of commercial porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae monovalent and bivalent vaccines against a dual challenge

Abstract

The objective of this study was to compare the efficacy of commercially available porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae vaccines. A total of 80 pigs was randomly divided into 6 treatment groups; 4 of the groups each received a different vaccine as well as a dual challenge. The remaining 2 groups were used as controls, 1 of which also received a dual challenge. Two of the 4 groups of pigs were administered 2 monovalent vaccines (designated as either monovalent vaccine A or B) of PCV2 at 7 days old and of M. hyopneumoniae at 21 days old. The remaining 2 vaccinated groups of pigs received a bivalent vaccine (designated as either bivalent vaccine A or B) of PCV2 and M. hyopneumoniae at 21 days old. All 4 vaccinated groups were challenged with M. hyopneumoniae at 42 days old [-14 d post-challenge (dpc)], followed by a PCV2d challenge at 56 days old (0 dpc). All 4 vaccinated/challenged groups displayed a reduction in clinical signs, PCV2d viremia, nasal shedding of M. hyopneumoniae, and lung lesions compared with pigs in the unvaccinated and challenged groups. Vaccination and challenge improved growth performance and increased the immunologic responses (M. hyopneumoniae- and PCV2-specific antibodies and interferon-γ-secreting cells) when compared to pigs in the unvaccinated/challenged groups. Pigs in groups vaccinated with either a monovalent or bivalent vaccine A treatment and challenge produced a larger amount of M. hyopneumoniae- and PCV2d-specific interferon-γ-secreting cells within the pigs and simultaneously reduced the nasal shedding of M. hyopneumoniae and PCV2d viremia compared with groups vaccinated with either a monovalent or bivalent vaccine B treatment and challenge. Both the bivalent vaccines and the respective monovalent vaccines were efficacious against a dual challenge of M. hyopneumoniae and PCV2d.

Figure 1

Experimental design. Pigs were administered a vaccine against M. hyopneumoniae (Mhp) and/or porcine circovirus type 2 (PCV2) and challenged with M. hyopneumoniae and PCV2 on certain days as shown. A number of pigs were necropsied as shown.

Figure 2

Clinical respiratory sign scores in the different groups: VacA-M+P/Ch ( ); VacA-PM/Ch ( ); VacB-M+P/Ch ( ); VacB-PM/Ch ( ); UnVac/Ch (■); and UnVac/UnCh (△). Different letters within a sampling point mean statistically significant differences (P < 0.05).

Figure 3

Quantification of M. hyopneumoniae (Mhp) DNA and PCV2 DNA. A — Mean values of the genomic copy numbers of M. hyopneumoniae DNA in the nasal swabs and B — Mean values of the genomic copy numbers of PCV2 DNA in the serum samples in the different groups: VacA-M+P/Ch ( ); VacA-PM/Ch ( ); VacB-M+P/Ch ( ); VacB-PM/Ch ( ); UnVac/Ch (■); and UnVac/UnCh (△). Different letters within a sampling point mean statistically significant differences (P < 0.05).

Figure 4

Enzyme-linked immunosorbent assay. A — Mean values of the anti-M. hyopneumoniae (Mhp) antibody levels and B — Mean values of the anti-PCV2 antibody levels in the different groups: VacA-M+P/Ch ( ); VacA-PM/Ch ( ); VacB-M+P/Ch ( ); VacB-PM/Ch ( ); UnVac/Ch (■); and UnVac/UnCh (△). Different letters within a sampling point mean statistically significant differences (P < 0.05).

Figure 5

Numbers of interferon-γ-secreting cells (IFN-γ-SCs). A — Mean number of Mycoplasma hyopneumoniae (Mhp)-specific IFN-γ-SCs in peripheral blood mononuclear cells (PBMCs) and B — Mean number of PCV2-specific IFN-γ-SCs in PBMCs in the different groups: VacA-M+P/Ch ( ); VacA-PM/Ch ( ); VacB-M+P/Ch ( ); VacB-PM/Ch ( ); UnVac/Ch (■); and UnVac/UnCh (△). Different letters within a sampling point mean statistically significant differences (P < 0.05).