Field Evaluation of a Ready-to-Use Porcine Circovirus Type 2 and Mycoplasma hyopneumoniae Vaccine in Naturally Infected Farms in Taiwan

Abstract

Porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae (MHP) are both important and common pathogens in the pig industry. Both pathogens are major contributors to the porcine respiratory disease complex and serve to potentiate other bacterial infections such as Actinobacillus pleuropneumonia. This study aims to evaluate the efficacy of a ready-to-use bivalent PCV2 and MHP vaccine in the field under naturally PCV2-infected farms against existing monovalent options. We evaluated PCV2 viremia, PCV2 antibodies, and lung lesion scores in slaughtered pigs in our study across four farms in Taiwan. Our results found that in two out of four farms, the piglets vaccinated with Porcilis^® PCV M Hyo had superior whole-life PCV2 viremia reduction compared to the existing vaccination program on farms. In the lung lesion scoring, the Porcilis^® PCV M Hyo group had significantly lower Actinobacillus pleuropneumonia-type lesions in pigs than in the competitor group in two out of three farms evaluated. In this field trial, Porcilis^® PCV M Hyo proved to be efficacious in protecting piglets against both PCV2 viremia and the impact of MHP secondary infection, in the context of a reduction in viremia and reduced APP-like lesions found at slaughter.

Keywords: Actinobacillus pleuropneumoniae; Mycoplasma hyopneumoniae; bivalent vaccine; porcine circovirus type 2; porcine respiratory disease complex; swine; vaccination.

Figure 1

Comparison of PCV2 antibody and viremia at different weeks of age in Farms A, B, C and D. Blue and green lines represent control and experimental groups (Porcilis^® PCV M Hyo), respectively. Solid and hollow represent PCV2 antibodies and viremia at different weeks of age. The dotted line indicates the threshold for the presence of PCV2 antibody (0.5). The X-axis represents different ages. The left Y-axis represents the S/P value of PCV2 antibody. The Y axis on the right represents the PCV2 viral load. Error bars indicate 95% confidence interval for the mean.

Figure 2

Comparison of PCV2 viremia between the two groups at different ages in the study. Blue and green represent group 1 (control group) and group 2 (experimental group), respectively. PCV2 loads of less than 10³, 10³ to 10⁴ (red area), and greater than 10⁴ DNA copies/μL (red dotted line) in serum can be used to categorize pigs as subclinically infected, suspected, and PCVAD, respectively. The black dotted line is the PCV2 qPCR detection limit, and the blue and green on the X axis represent a negative PCV2 qPCR assay. Error bars indicate 95% confidence interval for the mean. p values < 0.05, <0.01 and 0.001 are considered statistically significant, highly significant and very highly significant, respectively.