Quantitative proteomics by 2-DE, 16O/18O labelling and linear ion trap mass spectrometry analysis of lymph nodes from piglets inoculated by porcine circovirus type 2.

Porcine circovirus type 2 (PCV2) has been identified as the essential causal agent of postweaning multisystemic wasting syndrome. However, little is known regarding the mechanism(s) underlying the pathogenesis of PCV2-induced disease and the interaction of the virus with the host immune system. Here, we present a proteomics study on inguinal lymph nodes of piglets inoculated with PCV2, in order to better understand the pathogenesis of postweaning multisystemic wasting syndrome and the pathways might be affected after infection. We used two proteomics strategies, 2-DE and 1-DE followed by (16)O/(18)O peptide labelling and peptide identification and quantification by MS. More than 100 proteins were found to be differentially regulated and the results obtained by the two strategies were fairly concordant but also complementary, the (18)O labelling approach being a more robust alternative. Analysis of these proteins by systems biology tools revealed the implication of acute phase response and NrF2-mediated oxidative stress, suggesting a putative role for these pathways in the pig immune response. Besides, CD81 was found to be up-regulated, suggesting a possible role in the internalization of the virus. The use of proteomics technologies together with biology analysis systems opens up the way to gain more exhaustive and systematic knowledge of virus-pathogen interactions.