Intestinal gene expression in pigs experimentally co-infected with PCV2 and PPV

The objective of the present study was to characterize the local immune reaction in the intestine of pigs experimentally infected with PCV2 and PPV. Archived intestinal material from an experimental study in which pigs were co-infected with a Swedish isolate of PCV2 (S-PCV2) and PPV, or a reference isolate of PCV2 (PCV2-1010) and PPV, were used. The intestinal samples were analysed by qPCR for expression of a number of selected cytokines and the overall gene expression in the intestine was screened by cDNA microarray. Analyses by qPCR showed that pigs infected with PCV2-1010/PPV displayed a significantly increased mRNA expression for IL-6 (p < 0.05), IL-10 (p < 0.05) and IFN-γ (p < 0.05). The microarray screening revealed a strong up-regulation of IFITM3 along with several other interferon-stimulated genes (ISGs) in pigs infected with PCV2/PPV. The analyses also indicated differences between the two isolates. Fewer pigs infected with S-PCV2/PPV expressed the cytokines detected by qPCR, compared to pigs infected with PCV2-1010/PPV, and pigs infected with S-PCV2/PPV displayed a higher proportion of down-regulated genes than PCV2-1010/PPV-infected pigs.