Identification of porcine serum proteins modified in response to HP-PRRSV HuN4 infection by two-dimensional differential gel electrophoresis.

Since 2006, highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) has become the major pathogen attributed to the prevalent porcine reproductive and respiratory syndrome (PRRS) in China. The present study aims to identify serum proteins modified in response to infection of HuN4, a HP-PRRSV strain isolated from a farm in 2006. 2-D DIGE analysis allowed for the detection of 19 differentially expressed protein spots, of which 18 were identified by MALDI-TOF/TOF MS. These 18 spots represented for a total of 9 proteins (6 up-regulated and 3 down-regulated), most of which belonged to the acute phase proteins in swine and showed a trend of regression in the late phase of the experiment. One of a series of AGP spots was identified for the first time to be decreased in acute phase of PRRSV infection in swine. But the whole level of the protein in the serum did not show significant changes by Western blot. The rising tendency of Hp was confirmed by Western blot and ELISA. These altered proteins were probably involved in the inflammatory process triggered by HuN4 and in alleviating the oxidative damage occurring in the process. In summary, these results may provide new insights into understanding the mechanisms of HP-PRRSV infection.