1,478 research outputs found
Tick-borne encephalitis virus induces chemokine RANTES expression via activation of IRF-3 pathway.
BACKGROUND: Tick-borne encephalitis virus (TBEV) is one of the most important flaviviruses that targets the central nervous system (CNS) and causes encephalitides in humans. Although neuroinflammatory mechanisms may contribute to brain tissue destruction, the induction pathways and potential roles of specific chemokines in TBEV-mediated neurological disease are poorly understood. METHODS: BALB/c mice were intracerebrally injected with TBEV, followed by evaluation of chemokine and cytokine profiles using protein array analysis. The virus-infected mice were treated with the CC chemokine antagonist Met-RANTES or anti-RANTES mAb to determine the role of RANTES in affecting TBEV-induced neurological disease. The underlying signaling mechanisms were delineated using RANTES promoter luciferase reporter assay, siRNA-mediated knockdown, and pharmacological inhibitors in human brain-derived cell culture models. RESULTS: In a mouse model, pathological features including marked inflammatory cell infiltrates were observed in brain sections, which correlated with a robust up-regulation of RANTES within the brain but not in peripheral tissues and sera. Antagonizing RANTES within CNS extended the survival of mice and reduced accumulation of infiltrating cells in the brain after TBEV infection. Through in vitro studies, we show that virus infection up-regulated RANTES production at both mRNA and protein levels in human brain-derived cell lines and primary progenitor-derived astrocytes. Furthermore, IRF-3 pathway appeared to be essential for TBEV-induced RANTES production. Site mutation of an IRF-3-binding motif abrogated the RANTES promoter activity in virus-infected brain cells. Moreover, IRF-3 was activated upon TBEV infection as evidenced by phosphorylation of TBK1 and IRF-3, while blockade of IRF-3 activation drastically reduced virus-induced RANTES expression. CONCLUSIONS: Our findings together provide insights into the molecular mechanism underlying RANTES production induced by TBEV, highlighting its potential importance in the process of neuroinflammatory responses to TBEV infection
SUMO Modification Stabilizes Enterovirus 71 Polymerase 3D To Facilitate Viral Replication.
Accumulating evidence suggests that viruses hijack cellular proteins to circumvent the host immune system. Ubiquitination and SUMOylation are extensively studied posttranslational modifications (PTMs) that play critical roles in diverse biological processes. Cross talk between ubiquitination and SUMOylation of both host and viral proteins has been reported to result in distinct functional consequences. Enterovirus 71 (EV71), an RNA virus belonging to the family Picornaviridae, is a common cause of hand, foot, and mouth disease. Little is known concerning how host PTM systems interact with enteroviruses. Here, we demonstrate that the 3D protein, an RNA-dependent RNA polymerase (RdRp) of EV71, is modified by small ubiquitin-like modifier 1 (SUMO-1) both during infection and in vitro Residues K159 and L150/D151/L152 were responsible for 3D SUMOylation as determined by bioinformatics prediction combined with site-directed mutagenesis. Also, primer-dependent polymerase assays indicated that mutation of SUMOylation sites impaired 3D polymerase activity and virus replication. Moreover, 3D is ubiquitinated in a SUMO-dependent manner, and SUMOylation is crucial for 3D stability, which may be due to the interplay between the two PTMs. Importantly, increasing the level of SUMO-1 in EV71-infected cells augmented the SUMOylation and ubiquitination levels of 3D, leading to enhanced replication of EV71. These results together suggested that SUMO and ubiquitin cooperatively regulated EV71 infection, either by SUMO-ubiquitin hybrid chains or by ubiquitin conjugating to the exposed lysine residue through SUMOylation. Our study provides new insight into how a virus utilizes cellular pathways to facilitate its replication. IMPORTANCE: Infection with enterovirus 71 (EV71) often causes neurological diseases in children, and EV71 is responsible for the majority of fatalities. Based on a better understanding of interplay between virus and host cell, antiviral drugs against enteroviruses may be developed. As a dynamic cellular process of posttranslational modification, SUMOylation regulates global cellular protein localization, interaction, stability, and enzymatic activity. However, little is known concerning how SUMOylation directly influences virus replication by targeting viral polymerase. Here, we found that EV71 polymerase 3D was SUMOylated during EV71 infection and in vitro Moreover, the SUMOylation sites were determined, and in vitro polymerase assays indicated that mutations at SUMOylation sites could impair polymerase synthesis. Importantly, 3D is ubiquitinated in a SUMOylation-dependent manner that enhances the stability of the viral polymerase. Our findings indicate that the two modifications likely cooperatively enhance virus replication. Our study may offer a new therapeutic strategy against virus replication
A unique distant submillimeter galaxy with an X-ray-obscured radio-luminous active galactic nucleus
We present a multiwavelength study of an atypical submillimeter galaxy in the
GOODS-North field, with the aim to understand its physical properties of
stellar and dust emission, as well as the central AGN activity. Although it is
shown that the source is likely an extremely dusty galaxy at high redshift, its
exact position of submillimeter emission is unknown. With the new NOEMA
interferometric imaging, we confirm that the source is a unique dusty galaxy.
It has no obvious counterpart in the optical and even NIR images observed with
HST at lambda~<1.4um. Photometric-redshift analyses from both stellar and dust
SED suggest it to likely be at z~>4, though a lower redshift at z~>3.1 cannot
be fully ruled out (at 90% confidence interval). Explaining its unusual
optical-to-NIR properties requires an old stellar population (~0.67 Gyr),
coexisting with a very dusty ongoing starburst component. The latter is
contributing to the FIR emission, with its rest-frame UV and optical light
being largely obscured along our line of sight. If the observed fluxes at the
rest-frame optical/NIR wavelengths were mainly contributed by old stars, a
total stellar mass of ~3.5x10^11Msun would be obtained. An X-ray spectral
analysis suggests that this galaxy harbors a heavily obscured AGN with
N_H=3.3x10^23 cm^-2 and an intrinsic 2-10 keV luminosity of L_X~2.6x10^44
erg/s, which places this object among distant type 2 quasars. The radio
emission of the source is extremely bright, which is an order of magnitude
higher than the star-formation-powered emission, making it one of the most
distant radio-luminous dusty galaxies. The combined characteristics of the
galaxy suggest that the source appears to have been caught in a rare but
critical transition stage in the evolution of submillimeter galaxies, where we
are witnessing the birth of a young AGN and possibly the earliest stage of its
jet formation and feedback.Comment: 13 pages in printer format, 10 figures, 1 table, accepted for
publication in the A&
Effect of process parameters on forming quality of Mg alloy(MZ21)-Al alloy(7075) composite pipe
This paper mainly studies the effect of process parameters on the deformation mechanism of MZ21 magnesium alloy and 7075 aluminum alloy bimetal composite pipe in spinning process.The two parameters of spinning, the rotary wheel feed ratio and the double tube wall thinning rate were selected to study, and the influence rule of each process parameter on the forming quality of composite tube was simulated by Simufact software. Under different thinning rates of the total wall thickness, the coordinated deformation and the rebound law of the wall thickness of the composite pipe are obtained. The results provide a certain reference for the preparation of magnesium aluminum composite pipe and the selection of reasonable spinning parameters
Feasibility study of SiCp reinforced TC11 titanium alloy under selective laser melting
In order to improve the comprehensive performance of titanium alloy, the mechanical ball milling method was used to optimize the preparation of composite powder by different ball milling time, rotation speed and SiCp content. SiCp/TC11 composites were prepared by selective laser melting (SLM) technology. The results show that the milling speed, time and SiC content have an effect on the morphology, size and distribution of the composite powder. Compared with TC11, the hardness of the composite prepared by SLM process is 426,723 HV, which is increased by 15,10 %, and the enhancement effect of SiCp is successfully realized.The research results provide a theoretical basis for obtaining high-quality aerospace titanium alloy parts
Feasibility study of SiCp reinforced TC11 titanium alloy under selective laser melting
In order to improve the comprehensive performance of titanium alloy, the mechanical ball milling method was used to optimize the preparation of composite powder by different ball milling time, rotation speed and SiCp content. SiCp/TC11 composites were prepared by selective laser melting (SLM) technology. The results show that the milling speed, time and SiC content have an effect on the morphology, size and distribution of the composite powder. Compared with TC11, the hardness of the composite prepared by SLM process is 426,723 HV, which is increased by 15,10 %, and the enhancement effect of SiCp is successfully realized.The research results provide a theoretical basis for obtaining high-quality aerospace titanium alloy parts
Optical loss compensation in a bulk left-handed metamaterial by the gain in quantum dots
A bulk left-handed metamaterial with fishnet structure is investigated to
show the optical loss compensation via surface plasmon amplification, with the
assistance of a Gaussian gain in PbS quantum dots. The optical resonance
enhancement around 200 THz is confirmed by the retrieval method. By exploring
the dependence of propagation loss on the gain coefficient and metamaterial
thickness, we verify numerically that the left-handed response can endure a
large propagation thickness with ultralow and stable loss under a certain gain
coefficient.Comment: 6 pages with 4 figure
Emerging and reemerging helminthiases and the public health of China.
Despite great strides in their control throughout the People's Republic of China, helminth infections remain an important public health problem. The Institute of Parasitic Diseases of the Chinese Academy of Preventive Medicine, under the guidance of the Chinese Ministry of Health, completed a nationwide survey of more than 1 million people that showed the high prevalence and intensity of intestinal nematode infections; prevalence can sometimes exceed 50% in the Yangtze River valley provinces. Schistosoma japonicum is also a major cause of illness in this region. Attempts to control Chinese helminthic diseases with conventional anthelminthic drugs have been partially thwarted by high posttreatment rates of reinfection. Recently, several new human trematode pathogens have been identified. Novel approaches to chemoprophylaxis and vaccination may alleviate the public health problem caused by Chinese helminths. However, recombinant helminth vaccine development will depend on first cataloguing the extensive genetic diversity of Chinese helminths and candidate vaccine antigens. Evidence from biogeography, genetics, and systematics suggests that the genetic diversification of Chinese helminths and their vectors is an ongoing evolutionary process that began 12 million years ago near the convergence of major Asian river systems. Construction of the Three Gorges Super Dam on the Yangtze River may promote the emergence and reemergence of new helminths and their snail vector
Study on cold spinning deformation behavior and load mechanism of conical thin-walled aluminum alloy parts
Aiming at the problem that the wall thickness uniformity of conical thin-walled aluminum alloy parts formed by single-pass spinning is difficult to control, this paper systematically studies the influence of different spinning parameters on the material evolution law and load mechanism during the forming process of 1070 thin-walled aluminum alloy. The effects of slab thickness, roller gap and feed ratio on the macroscopic forming quality and mechanical load of 1070 thin-walled aluminum alloy conical parts were simulated by Simufact.forming software. Finally, the optimal spinning parameters of 1070 thin-walled aluminum alloy conical parts were obtained. The final results show that increasing the diameter-thickness ratio of the blank can prevent wrinkling, and reasonable spinning parameters can improve the uniformity of the wall thickness of the product
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