Genomic expression profiling in lymph nodes with lymphoid depletion from porcine circovirus 2-infected pigs

Porcine circovirus type 2 (PCV2) is the main causative agent of porcine circovirus-associated disease, such as post-weaning multisystemic wasting syndrome, which involves lymphocyte depletion. However, little is known about the molecular mechanisms of lymphoid depletion. To gain insight into the interaction between virus and host cells, microarrays were used to analyse changes in genomic expression in lymph nodes following PCV2 infection of pigs, together with negative controls. Total RNA was subjected to microarray analysis with an Affymetrix Porcine Genome Array GeneChip. Of the 23,256 pig genes arrayed on a chip, 160 genes showed altered expression after infection (upregulated, 64; downregulated, 96). The altered genomic expression of 18 selected genes was confirmed by quantitative real-time PCR. The expression changes of numerous genes involved in innate immune defence (TLR1, CD14 and CD180), immunosuppressed responses (FGL2 and GPNMB), pro-inflammatory signals (galectin-3) and fasting processes (ANGPTL-4) indicate that PCV2 has developed an intricate mechanism to cause immunosuppression, inflammatory cell infiltration and weight loss in pigs. The results of this study provide a basis for understanding the molecular pathogenesis of PCV2 infection.