The nonstructural protein 10 (nsp10) of porcine reproductive and respiratory syndrome virus (PRRSV) encodes for helicase which plays a vital role in viral replication.  In the present study, a truncated form of nsp10, termed nsp10a, was found in PRRSV-infected cells and the production of nsp10a was strain-specific.  Mass spectrometric analysis and deletion mutagenesis indicated that nsp10a may be short of about 70 amino acids in the N terminus of nsp10.  Further studies by rescuing recombinant viruses showed that the Glu-69 in nsp10 was the key amino acid for nsp10a production.  Finally, we demonstrated that nsp10a exerted little influence on the growth kinetics of PRRSV in vitro. 

    Porcine reproductive and respiratory syndrome virus (PRRSV) actively induces cell apoptosis both in vitro and in vivo, which can contribute critically to viral pathogenesis.  Previous studies have shown that the PRRSV nonstructural protein 4 (nsp4) is an important mediator of this process, but the underlying molecular details remain poorly understood.  In this study, we found that the PRRSV nsp4 interacted with the mitochondrial inner membrane protein cytochrome c1 (cyto.c1) and induced its proteolytic cleavage.  Interestingly, the cleaved N-terminal fragment of cyto.c1 was found to exert apoptotic activity, which could cause mitochondrial fragmentation, resulting in apoptotic cell death.  And RNA interference (RNAi) silencing experiments further confirmed the crucial role which cyto.c1 played in nsp4- and PRRSV-induced cell apoptosis.  Thus, our data provide an important piece of mechanistic clues for PRRSV-induced cell apoptosis and also elucidate a novel mechanism for the 3C-like proteases in this finding. 

   The glycoprotein 5 (GP5) of porcine reproductive and respiratory syndrome virus (PRRSV) is a multi-functional protein that plays important roles in virus assembly, entry and viral anti-host responses. In the present study, we investigated the cellular binding partners of GP5 by using lentivirus transduction coupled with immunoprecipitation and mass spectrometry. There were about 40 cellular proteins identified with high Confidence Icons by MS/MS. Ingenuity Pathway Analysis (IPA) indicated that these proteins could be assigned to different functional classes and networks. Furthermore, we validated some of the interactions by co-immunoprecipitation (Co-IP) and confocal microscopy, including those with mitofilin, a mitochondrial inner membrane protein that might be involved in PRRSV or GP5-induced apoptosis, and calnexin, a protein chaperone that might facilitate the folding and maturation of GP5. The interactome data contribute to understand the role and molecular mechanisms of GP5 in PRRSV pathogenesis.

The objective of the present investigation was to estimate the prevalence of Toxoplasma gondii infection and co-infection with porcine reproductive and respiratory syndrome virus (PRRSV), classical swine fever virus (CSFV) and porcine circovirus type 2 (PCV-2) in pigs in China. A total of 372 tissues or serum samples collected from pigs distributed in 9 provinces/ municipalities of China during the period from February 2011 to November 2012 were assayed for T. gondii antigens and antibodies using enzyme linked immunosorbent assay (ELISA) technique, while the PCR was designed for the detection of the PRRSV, CSFV and PCV-2, respectively. The total positive rate of T. gondii, PRSSV, CSFV and PCV-2 was 9.14% (34/372), 50.00% (186/372), 37.10% (138/372) and 3.23% (12/372), respectively. Among the 34 T. gondii positive samples, 26 samples were simultaneously infected with T. gondii and viruses, while the remaining eight samples were infected with T. gondii alone. In addition, the co-infection rate of T. gondii with PRSSV, T. gondii with PRSSV and CSFV, T. gondii with PRSSV and PCV-2, T. gondii with CSFV and PCV-2, T. gondii with PRSSV, CSFV and PCV-2 was 1.61% (6/372), 4.03% (15/372), 0.27% (1/372), 0.27% (1/372) and 0.81% (3/372), respectively. The results of the present survey revealed that PRRSV and CSFV were the common pathogens co-existing with porcine toxoplasmosis in China, and both of them could increase the chances of T. gondii infection in pig. This is the first report of T. gondii co-infections with viruses in pigs. It is very important to understand the interactions of parasite and virus, and can be used as reference data for the control and prevention of co-infections of T. gondii and viruses in pigs.