Yongyong Ji

Characterization of the 3a protein of SARS-associated coronavirus in infected vero E6 cells and SARS patients.

Abstract Proteomics was used to identify a protein encoded by ORF 3a in a SARS-associated coronavirus (SARS-CoV). Immuno-blotting revealed that interchain disulfide bonds might be formed between this protein and the spike protein. ELISA indicated that sera from SARS patients have significant positive reactions with synthesized peptides derived from the 3a protein. These results are concordant with that of a spike protein-derived peptide. A tendency exists for co-mutation between the 3a protein and the spike protein of SARS-CoV isolates, suggesting that the function of the 3a protein correlates with the spike protein. Taken together, the 3a protein might be tightly correlated to the spike protein in the SARS-CoV functions. The 3a protein may serve as a new clinical marker or drug target for SARS treatment.

Guanylate Binding Protein 4 Negatively Regulates Virus-Induced Type I IFN and Antiviral Response by Targeting IFN Regulatory Factor 7

IRF7 is known as the master regulator in virus-triggered induction of type I IFNs (IFN-I). In this study, we identify GBP4 virus-induced protein interacting with IRF7 as a negative regulator for IFN-I response. Overexpression of GBP4 inhibits virus-triggered activation of IRF7-dependent signaling, but has no effect on NF-κB signaling, whereas the knockdown of GBP4 has opposite effects. Furthermore, the supernatant from Sendai virus-infected cells in which GBP4 have been silenced inhibits the replication of vesicular stomatitis virus more efficiently. Competitive coimmunoprecipitation experiments indicate that overexpression of GBP4 disrupts the interactions between TRAF6 and IRF7, resulting in impaired TRAF6-mediated IRF7 ubiquitination. Our results suggest that GBP4 is a negative regulator of virus-triggered IFN-I production, and it is identified as a novel protein targeting IRF7 and inhibiting its function.

Negative Regulation of Nmi on Virus-Triggered Type I IFN Production by Targeting IRF7

Viral infection causes host cells to produce type I IFNs, which play a critical role in viral clearance. IFN regulatory factor (IRF) 7 is the master regulator of type I IFN-dependent immune responses. In this article, we report that N-Myc and STATs interactor (Nmi), a Sendai virus–inducible protein, interacted with IRF7 and inhibited virus-triggered type I IFN production. The overexpression of Nmi inhibited the Sendai virus–triggered induction of type I IFNs, whereas the knockdown of Nmi promoted IFN production. Furthermore, the enhanced production of IFNs resulting from Nmi knockdown was sufficient to protect cells from infection by vesicular stomatitis virus. In addition, Nmi was found to promote the K48-linked ubiquitination of IRF7 and the proteasome-dependent degradation of this protein. Finally, an impairment of antiviral responses is also detectable in Nmi-transgenic mice. These findings suggest that Nmi is a negative regulator of the virus-triggered induction of type I IFNs that targets IRF7.

ECM1 controls T(H)2 cell egress from lymph nodes through re-expression of S1P(1).

Type 2 helper T cells (TH2) are critically involved in allergies and asthma. Here we demonstrate that extracellular matrix protein-1 (ECM1) is highly and selectively expressed in TH2 cells. ECM1 deficiency caused impaired TH2 responses and reduced allergic airway inflammation in vivo. Functional analysis demonstrated that although the TH2 polarization of ECM1-deficient cells was unimpaired, these cells had a defect in migration and were retained in peripheral lymphoid organs. This was associated with reduced expression of KLF2 and S1P1. We also found that ECM1 could directly bind the interleukin-2 (IL-2) receptor to inhibit IL-2 signaling and activate S1P1 expression. Our data identify a previously unknown function of ECM1 in regulating TH2 cell migration through control of KLF2 and S1P1 expression.

Dec2 Promotes Th2 Cell Differentiation by Enhancing IL-2R Signaling

Th cell differentiation is precisely regulated by thousands of genes at different stages. In the present study, we demonstrate that Dec2, a transcription factor belonging to the bHLH (basic helix-loop-helix) superfamily, is progressively induced during the course of Th2 differentiation, especially at the late stage. The up-regulated Dec2 can strongly promote Th2 development under Th2-inducing conditions, as evidenced by retrovirus-mediated gene transfer or transgenic manipulation. In addition, an enhancement of Th2 responses is also detectable in Dec2 transgenic mice in vivo. Conversely, RNA interference-mediated suppression of endogenous Dec2 could attenuate Th2 differentiation. Finally, we show that the enhanced Th2 development is at least in part due to substantial up-regulation of CD25 expression elicited by Dec2, thereby resulting in hyperresponsiveness to IL-2 stimulation.

Characterization and application of monoclonal antibodies against N protein of SARS-coronavirus

Abstract Severe acute respiratory syndrome-coronavirus (SARS-CoV) causes an infectious disease through respiratory route. Diagnosing the disease effectively and accurately at early stage is essential for preventing the disease transmission and performing antiviral treatment. In this study, we raised monoclonal antibodies (mAbs) against the nucleocapsid (N) protein of SARS-CoV and mapped epitopes by using different truncated N protein fragments. The mapping of those epitopes was valuable for constructing pair-Abs used in serological diagnosis. The results showed that all of the six raised mAbs were divided into two groups recognizing the region of amino acids 249–317 (A group) or 317–395 (B group). This region spanning amino acids 249–395 contains predominant B cell epitopes located at the C-terminus of N protein. One pair-Abs, consisting of N protein-specific rabbit polyclonal antibody and SARS-CoV N protein-specific mAb, was selected to construct a sandwich ELISA-kit. The kit was able to specifically detect SARS-CoV N proteins in serum samples.

Development of retinol-binding protein 4 immunocolloidal gold fast test strip using high-sensitivity monoclonal antibodies generated by DNA immunization

DNA immunization is an efficient method for high-affinity monoclonal antibody generation. Here, we describe the generation of several high-quality monoclonal antibodies (mAbs) against retinol-binding protein 4 (RBP4), an important marker for kidney abnormality and dysfunction, with a combination method of DNA priming and protein boost. The mAbs generated could bind to RBP4 with high sensitivity and using these mAbs, an immunocolloidal gold fast test strip was constructed. The strip can give a result in <5 min and is very sensitive with a detection limit of about 1 ng/ml. A small-scale clinical test revealed that the result of this strip was well in accordance with that of an enzyme-labeled immunosorbent assay kit currently available on the market. Consequently, it could be useful for more convenient and faster RBP4 determination in the clinic.

Spectroscopic properties of Ho3+ doped CaNb2O6 crystal

Abstract Results of the growth and annealing processes of Ho3+:CaNb2O6 crystal with high oxygen defects were reported. The spectroscopic properties of Ho3+:CaNb2O6 were also analysed, and the decay curves of the bulk and powder samples in correspondence with the emission 5I7→5I8 at 2·0 μm were recorded. The effects of radiative trapping on the final results were also indicated, and the final value of the fluorescence lifetimes of 5I7→5I8 transition is calculated to be 5·19 ms. CaNb2O6 crystal was shown to be a prospective material for an infrared laser medium at 2·0 μm.