Profiling of cellular proteins in porcine reproductive and respiratory syndrome virus virions by proteomics analysis

In our experiment, sixty one cellular proteins were identified in highly purified PRRSV virions by two-dimensional gel electrophoresis coupled with mass spectrometric approaches. The identified cellular proteins could be grouped into eight functional categories including cytoskeletal proteins, chaperones, macromolecular biosynthesis proteins, metabolism-associated proteins, calcium-dependent membrane-binding proteins and other functional proteins. Among the identified proteins, four have not yet been reported in other studied envelope viruses, namely, guanine nucleotide-binding proteins, tyrosine 3-monooxygenase/tryptophan 5-monooxygenase, peroxiredoxin 1 and galectin-1 protein. The presence of five selected cellular proteins (i.e., β-actin, Tubulin, Annexin A2, heat shock protein Hsp27, and calcium binding proteins S100) in the highly purified PRRSV virions was validated by Western blot and immunogold labeling assays.Taken together, the present study has demonstrated the incorporation of cellular proteins in PRRSV virions, which provides valuable information for the further investigations for the effects of individual cellular proteins on the viral replication, assembly, and pathogenesis.Porcine reproductive and respiratory syndrome (PRRS) is an economically important disease of swine throughout the world, characterized by severe reproductive problem with late term abortions in sows and severe respiratory ailment leading to increased mortality in young pigs [1,2]. The disease was first reported in the United States in 1987 and subsequently in Europe in 1991, reaching Southeast Asia and Japan in 1995 [3,4]. The disease is now pandemic in many swine-producing countries and has become one of the most serious threats to intensive swine industry. In June 2006, the outbreak of "high fever" in China, caused by highly pathogenic PRRSV infection, spread to more than 10 provinces and took a huge toll in swine industry [5].Porcine reproductive and respiratory syndrome virus (