Genome-wide gene expression profiles in lung tissues of pig breeds differing in resistance to porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome caused by porcine reproductive and respiratory syndrome virus (PRRSV) is an infectious disease characterized by severe reproductive deficiency in pregnant sows, respiratory symptoms in piglets, and high mortality. In this study, we employed Affymetrix microarray chip technology to compare the gene expression profiles of lung tissue samples from Dapulian (DPL) pigs (a Chinese indigenous pig breed) and DurocLandraceYorkshire (DLY) pigs after infection with PRRSV. During infection with PRRSV, the DLY pigs exhibited the range of clinical features that typify the disease, while the DPL pigs exhibited only mild signs of the disease. The percentage of CD8+ T cells in the DPL pigs was significantly higher than that in the DLY pigs at 21 days post-infection (dpi) (p< 0.05). Interleukin (IL) 1 beta (IL-1) and IL-2 levels showed significant differences between the DPL and DLY pigs at 0 and 7 dpi (p< 0.01). For IL-10, the DLY pigs had significantly higher values than the DPL pigs at 0 and 7 dpi (p< 0.01). Significant differences were apparent between the DPL and DLY pigs in terms of their tumor necrosis factor-alpha (TNF-) and interferon (IFN)-gamma (IFN-) levels at 0 and 7 dpi (p< 0.01). Microarray data revealed 16 differentially expressed genes in the lung tissue samples from the DLY and DPL pigs (q5%), of which LOC100516029 and LOC100523005 were up-regulated in the PRRSV-infected DPL pigs, while the other 14 genes were down-regulated in the PRRSV-infected DPL pigs compared with the PRRSV-infected DLY pigs. The expression levels of 10 of the 16 genes, namely CCDC84, C6ORF52, THYMOSIN, PRVE, HSPCB, CYP2J2, AMPD3, TOR1AIP2, PTGES3, and ACOX3, were validated by real-time quantitative RT-PCR. This study provides a platform for further investigation of the molecular mechanisms underlying the differential immune responses to PRRSV infection in different breeds or lines of pig.

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