Effect of human activated NRAS on replication of delNS1 H5N1 influenza virus in MDCK cells

<p>Abstract</p> <p>Background</p> <p>RAS, coded by <it>ras </it>proto-oncogenes, played an important role in signal transmission to regulate cell growth and differentiation. Host activation of RAS was significant for IFN-sensitive vaccinia virus (delE3L) or attenuate influenza virus in unallowable cells.</p> <p>Results</p> <p>Huamn <it>NRAS </it>gene was activated by mutating in codon 61. Then the activation of NRAS was detected by western blot in MDCK cells. The delNS1 H5N1 influenza virus with deletion of NS1 eIF4GI binding domain was weak multiplication in MDCK cells. And the replication of delNS1 virus and expression of IFN-beta and IRF-3 were detected by Real-time PCR in MDCK cells infected with delNS1 virus. It was found that the delNS1 virus had a significant increase in MDCK cells when the NRAS was activated, and yet, expression of IRF-3 and IFN-beta were restrained.</p> <p>Conclusions</p> <p>The study demonstrated that activated NRAS played an important part for delNS1 virus replication in MDCK cells. Activated NRAS might be down-regulating the expression of antiviral cellular factors in delNS1 virus infected cells.</p

Streptococcus suis 2 Transcriptional Regulator TstS Stimulates Cytokine Production and Bacteremia to Promote Streptococcal Toxic Shock-Like Syndrome

Two large-scale outbreaks of streptococcal toxic shock-like syndrome (STSLS) have revealed Streptococcus suis 2 to be a severe and evolving human pathogen. We investigated the mechanism by which S. suis 2 causes STSLS. The transcript abundance of the transcriptional regulator gene tstS was found to be upregulated during experimental infection. Compared with the wild-type 05ZY strain, a tstS deletion mutant (ΔtstS) elicited reduced cytokine secretion in macrophages. In a murine infection model, tstS deletion resulted in decreased virulence and bacterial load, and affected cytokine production. Moreover, TstS expression in the P1/7 strain of S. suis led to the induction of STSLS in the infected mice. This is noteworthy because, although it is virulent, the P1/7 strain does not normally induce STSLS. Through a microarray-based comparative transcriptomics analysis, we found that TstS regulates multiple metabolism-related genes and several virulence-related genes associated with immune evasion

Immunoproteomic analysis of outer membrane proteins and extracellular proteins of Actinobacillus pleuropneumoniae JL03 serotype 3

<p>Abstract</p> <p>Background</p> <p><it>Actinobacillus pleuropneumoniae </it>is the causative agent of porcine contagious pleuropneumonia, a highly contagious respiratory infection in pigs, and all the 15 serotypes are able to cause disease. Current vaccines including subunit vaccines could not provide satisfactory protection against <it>A. pleuropneumoniae</it>. In this study, the immunoproteomic approach was applied to the analysis of extracellular and outer membrane proteins of <it>A. pleuropneumoniae </it>JL03 serotype 3 for the identification of novel immunogenic proteins for <it>A. pleuropneumoniae</it>.</p> <p>Results</p> <p>A total of 30 immunogenic proteins were identified from outer membrane and extracellular proteins of JL03 serotype 3, of which 6 were known antigens and 24 were novel immunogenic proteins for <it>A. pleuropneumoniae</it>.</p> <p>Conclusion</p> <p>These data provide information about novel immunogenic proteins for <it>A. pleuropneumoniae </it>serotype 3, and are expected to aid in development of novel vaccines against <it>A. pleuropneumoniae</it>.</p

The C-Terminal Effector Domain of Non-Structural Protein 1 of Influenza A Virus Blocks IFN-β Production by Targeting TNF Receptor-Associated Factor 3

Influenza A virus non-structural protein 1 (NS1) antagonizes interferon response through diverse strategies, particularly by inhibiting the activation of interferon regulatory factor 3 (IRF3) and IFN-β transcription. However, the underlying mechanisms used by the NS1 C-terminal effector domain (ED) to inhibit the activation of IFN-β pathway are not well understood. In this study, we used influenza virus subtype of H5N1 to demonstrate that the NS1 C-terminal ED but not the N-terminal RNA-binding domain, binds TNF receptor-associated factor 3 (TRAF3). This results in an attenuation of the type I IFN signaling pathway. We found that the NS1 C-terminal ED (named NS1/126-225) inhibits the active caspase activation and recruitment domain-containing form of RIG-I [RIG-I(N)]-induced IFN-β reporter activity, the phosphorylation of IRF3, and the induction of IFN-β. Further analysis showed that NS1/126-225 binds to TRAF3 through the TRAF domain, subsequently decreasing TRAF3 K63-linked ubiquitination. NS1/126-225 binding also disrupted the formation of the mitochondrial antiviral signaling (MAVS)–TRAF3 complex, increasing the recruitment of IKKε to MAVS; ultimately shutting down the RIG-I(N)-mediated signal transduction and cellular antiviral responses. This attenuation of cellular antiviral responses leads to evasion of the innate immune response. Taken together, our findings offer an important insight into the interplay between the influenza virus and host innate immunity

Effect of Water Distribution during Pre-drying on the Microstructure and Texture Properties of Peach Crisps Produced by Hot Air-Vacuum Freeze Drying

In this study, experiments were conducted to investigate the effect of moisture distribution during pre-drying on the microstructure and textural quality of hot air-vacuum freeze dried peach slices. The moisture distribution during the hot air pre-drying process at different temperatures (40, 60 and 80 ℃) and the product temperature during heating were monitored. Three levels of dry-basis moisture content (7, 6 and 5 g/g) were selected as moisture conversion points for each temperature. The color, shrinkage rate, microstructure, pore distribution, textural properties and hygroscopicity of peach crisps were measured. The results showed that drying temperature had a great impact on the moisture distribution during the pre-drying process, but the overall trends of moisture mobility were consistent among the different drying temperatures. The lower the moisture content of the pre-dried sample, the closer the color of the final dried sample to that of the fresh sample. The color of the sample dried at 40 ℃ with a moisture conversion point of 5 g/g was the closest to that of the fresh sample. Drying time had a greater effect on the shrinkage rate than temperature. It took longer to dry peach slices to the same moisture conversion point at 40 ℃ than 60 and 80 ℃. The sample shrank distinctly during both pre-drying and combined drying. There was a significant difference in the pore structure between the freeze-dried and combined dried samples. The sample with a moisture conversion point of 5 g/g had the most heterogeneous pore structure. The average hardness value of the hot air-vacuum freeze dried sample increased by 52.11% compared with that of the freeze-dried sample. The lower the moisture content of the pre-dried sample, the higher the hardness value of the hot air-vacuum freeze dried sample. This study showed that hot air pre-drying can effectively control the crunchiness and hardness of peach crisps. The decrease in the hygroscopicity of the hot air-vacuum freeze dried sample compared with the vacuum freeze dried one may be related to the structure changes during the pre-drying process. In summary, hot air-vacuum freeze drying is conducive to improving the texture quality and storage stability of peach crisps than vacuum freeze drying

Electrochemically Fabricated Surface-Mesostructured CuNi Bimetallic Catalysts for Hydrogen Production in Alkaline Media

Ni-based bimetallic films with 20 at.% and 45 at.% Cu and mesostructured surfaces were prepared by electrodeposition from an aqueous solution containing micelles of P123 triblock copolymer serving as a structure-directing agent. The pH value of the electrolytic solution had a key effect on both the resulting Cu/Ni ratio and the surface topology. The catalytic activity of the CuNi films toward hydrogen evolution reaction was investigated by cyclic voltammetry (CV) in 1 M KOH electrolyte at room temperature. The CuNi film showed the highest activity (even higher than that of a non-mesostructured pure Ni film), which was attributed to the Ni content at the utmost surface, as demonstrated by CV studies, as well as the presence of a highly corrugated surface

The Special Neuraminidase Stalk-Motif Responsible for Increased Virulence and Pathogenesis of H5N1 Influenza A Virus

The variation of highly pathogenic avian influenza H5N1 virus results in gradually increased virulence in poultry, and human cases continue to accumulate. The neuraminidase (NA) stalk region of influenza virus varies considerably and may associate with its virulence. The NA stalk region of all N1 subtype influenza A viruses can be divided into six different stalk-motifs, H5N1/2004-like (NA-wt), WSN-like, H5N1/97-like, PR/8-like, H7N1/99-like and H5N1/96-like. The NA-wt is a special NA stalk-motif which was first observed in H5N1 influenza virus in 2000, with a 20-amino acid deletion in the 49th to 68th positions of the stalk region. Here we show that there is a gradual increase of the special NA stalk-motif in H5N1 isolates from 2000 to 2007, and notably, the special stalk-motif is observed in all 173 H5N1 human isolates from 2004 to 2007. The recombinant H5N1 virus with the special stalk-motif possesses the highest virulence and pathogenicity in chicken and mice, while the recombinant viruses with the other stalk-motifs display attenuated phenotype. This indicates that the special stalk-motif has contributed to the high virulence and pathogenicity of H5N1 isolates since 2000. The gradually increasing emergence of the special NA stalk-motif in H5N1 isolates, especially in human isolates, deserves attention by all

Avian Influenza (H5N1) Virus in Waterfowl and Chickens, Central China

In 2004, 3 and 4 strains of avian influenza virus (subtype H5N1) were isolated from waterfowl and chickens, respectively, in central People’s Republic of China. Viral replication and pathogenicity were evaluated in chickens, quails, pigeons, and mice. We analyzed the sequences of the hemagglutinin and neuraminidase genes of the isolates and found broad diversity among them