Qiu-Yan Zhang

Bulk metallic glass formation of Cu-Zr-Ti-Sn alloys

Cu-Zr-Ti-Sn bulk metallic glasses were produced by copper mold casting. The effects of Sn addition on glass-forming ability (GFA), thermal stability of the Cu60Zr30Ti10 bulk metallic glass were investigated. It was found that a bulk metallic glass of 5 mm in diameter was prepared in a (Cu60Zr30Ti10)(99)Sn-1 alloy by copper mold casting. The addition of 1 at.% Sn is effective for an increase in GFA. The DeltaT(x) and T-g/T-I are 46 K and 0.63, respectively, for (Cu60Zr30Ti10)(99)Sn-1 alloy. With increasing the content of Sn, the value of TITI increases, but the alloys begin to lose bulk metallic GFA. The new parameter gamma has a better correlation with the GFA of the Cu-based alloys

Isolation and characterization of Zika virus imported to China using C6/36 mosquito cells

Here, we describe a cell culture-based procedure for isolating the infectious ZIKV (GenBank KU963796) from a human serum sample (ca. 50 μL) with an extremely low viral load (Ct value = 32).

Chemical Targeting of a G-Quadruplex RNA in the Ebola Virus L Gene

In the present study, our bioinformatics analysis first reveals the existence of a conserved guanine-rich sequence within the Zaire ebolavirus L gene. Using various methods, we show that this sequence tends to fold into G-quadruplex RNA. TMPyP4 treatment evidently inhibits L gene expression at the RNA level. Moreover, the mini-replicon assay demonstrates that TMPyP4 effectively inhibits the artificial Zaire ebolavirus mini-genome and is a more potent inhibitor than ribavirin. Although TMPyP4 treatment reduced the replication of the mutant mini-genome when G-quadruplex formation was abolished in the L gene, its inhibitory effect was significantly alleviated compared with wild-type. Our findings thus provide the first evidence that G-quadruplex RNA is present in a negative-sense RNA virus. Finally, G-quadruplex RNA stabilization may represent a new therapeutic strategy against Ebola virus disease.

Detection of Zika virus by SYBR green one-step real-time RT-PCR

The ongoing Zika virus (ZIKV) outbreak has rapidly spread to new areas of Americas, which were the first transmissions outside its traditional endemic areas in Africa and Asia. Due to the link with newborn defects and neurological disorder, numerous infected cases throughout the world and various mosquito vectors, the virus has been considered to be an international public health emergency. In the present study, we developed a SYBR Green based one-step real-time RT-PCR assay for rapid detection of ZIKV. Our results revealed that the real-time assay is highly specific and sensitive in detection of ZIKV in cell samples. Importantly, the replication of ZIKV at different time points in infected cells could be rapidly monitored by the real-time RT-PCR assay. Specifically, the real-time RT-PCR showed acceptable performance in measurement of infectious ZIKV RNA. This assay could detect ZIKV at a titer as low as 1PFU/mL. The real-time RT-PCR assay could be a useful tool for further virology surveillance and diagnosis of ZIKV.

Visualization of a neurotropic flavivirus infection in mouse reveals unique viscerotropism controlled by host type I interferon signaling

Flavivirus includes a large group of human pathogens with medical importance. Especially, neurotropic flaviviruses capable of invading central and peripheral nervous system, e.g. Japanese encephalitis virus (JEV) and Zika virus (ZIKV), are highly pathogenic to human and constitute major global health problems. However, the dynamic dissemination and pathogenesis of neurotropic flavivirus infections remain largely unknown. Here, using JEV as a model, we rationally designed and constructed a recombinant reporter virus that stably expressed Renilla luciferase (Rluc). The resulting JEV reporter virus (named Rluc-JEV) and parental JEV exhibited similar replication and infection characteristics, and the magnitude of Rluc activity correlated well with progeny viral production in vitro and in vivo. By using in vivo bioluminescence imaging (BLI) technology, we dissected the replication and dissemination dynamics of JEV infection in mice upon different inoculation routes. Interestingly, besides replicating in mouse brain, Rluc-JEV predominantly invaded the abdominal organs in mice with typical viscerotropism. Further tests in mice deficient in type I interferon (IFN) receptors demonstrated robust and prolonged viral replication in the intestine, spleen, liver, kidney and other abdominal organs. Combined with histopathological and immunohistochemical results, the host type I IFN signaling was evidenced as the major barrier to the viscerotropism and pathogenicity of this neurotropic flavivirus. Additionally, the Rluc-JEV platform was readily adapted for efficacy assay of known antiviral compounds and a live JE vaccine. Collectively, our study revealed abdominal organs as important targets of JEV infection in mice and profiled the unique viscerotropism trait controlled by the host type I IFN signaling. This in vivo visualization technology described here provides a powerful tool for testing antiviral agents and vaccine candidates for flaviviral infection.

Compressive fracture of Zr55Al10Ni5Cu30 bulk amorphous alloy at high temperatures

The fracture behavior of the Zr55Al10Ni5Cu30 bulk amorphous alloy under uniaxial compression at high temperatures has been investigated. At room temperature, the fracture occurred along the maximum shear plane which declined by 45degrees to the direction of the applied load, and a crack with serrated edge appeared on the ridge of the veins at the fracture surface for the Zr55Al10Ni5Cu30 bulk amorphous alloy. At high temperatures, the compressive fracture surface of the Zr55Al10Ni5Cu30 bulk amorphous alloy became much rougher than that at room temperature and steps appeared on the fracture surface. With increasing temperature, a different pattern from the vein-like morphology appeared on the fracture surface, which is very similar to the lava-flow. This type of fracture pattern is most likely due to the adiabatic heating created by plastic flow

Recovery of the Zika virus through an in vitro ligation approach

In this study, an in vitro ligation method was developed to assemble a full-length infectious cDNA clone of the Zika virus (ZIKV). Four contiguous cDNA subclones covering the complete ZIKV genome were constructed with unique BglI restriction sites at the ends of each fragment. The BglI restriction sites only allow in vitro ligation to happen between interconnecting restriction sites from adjacent cDNA fragments, resulting in an intact full-length cDNA of ZIKV. RNA transcripts derived from the full-length cDNA were infectious. The recombinant virus replicated as efficiently as the wild-type virus with similar growth kinetics and plaque morphologies in Vero and C6/36u2009cells. Both viruses were inhibited by NITD008 treatment. This in vitro ligation method will facilitate manipulation of the viral genome through genetic modifications of four separated subclones of ZIKV for the rapid and rational development of candidate vaccines and viral replication study.

Development of a replicon cell line-based high throughput antiviral assay for screening inhibitors of Zika virus

Abstract Zika virus (ZIKV) is an important emerging human pathogen associated with microcephaly, Guillain‐Barré syndrome and meningoencephalitis. Developing rapid and reliable HTS assay is important for ZIKV drug discovery. Here, we constructed a dicistronic ZIKV replicon (ZIKV‐Pac‐Rluc‐Rep) that contained the Renilla luciferase (Rluc) reporter gene separated from the puromycin N‐acetyl‐transferase (Pac) selectable marker by a short peptide cleavage site. A clonal replicon cell line stably expressing high level of ZIKV replicon was established by selection with puromycin. By optimizing cell number, compound concentration and incubation time, a robust replicon cell‐based HTS assay was developed with a calculated Z′ value of >0.5. The fully optimized assay was further validated using several known flavivirus replication inhibitors. Altogether, the replicon cell‐based HTS assay developed in this study will facilitate the discovery of antiviral compounds against ZIKV. HighlightsA novel dicistronic ZIKV replicon (ZIKV‐Pac‐Rluc‐Rep) was constructed.A clonal replicon cell line stably expressing high level of ZIKV replicon was established.A robust replicon cell‐based HTS assay was developed with a calculated Z′ value of >0.5.

Crystallization of mechanically alloyed amorphous Zr-Al-Ni-Cu-Ag alloy

chinese acad sci, inst met res, state key lab rsa, shenyang 110015, peoples r china.;zhang, qs (reprint author), chinese acad sci, inst met res, state key lab rsa, shenyang 110015, peoples r china

Development of a stable Japanese encephalitis virus replicon cell line for antiviral screening

Japanese encephalitis virus (JEV), an important pathogen in Eastern and Southern Asia and the Pacific, has spread to Australia and other territories in recent years. Although the vaccine for JEV has been used in some countries, development of efficient antiviral drugs is still an urgent requirement. Replicon systems have been widely used in the research of viral replication and antiviral screening for West Nile virus (WNV), yellow fever virus (YFV) and dengue virus (DENV). Here, a novel JEV replicon harboring the Rluc and Pac gene (JEV-Pac-Rluc-Rep) was constructed. Furthermore, we established a BHK-21 cell line harboring JEV-Pac-Rluc-Rep (BHK-21/PAC/Rluc cell line) through continuous puromycin selection. Characterization of cell line stability showed that the replicon RNA could persistently replicate in this cell line for at least up to 10 rounds of passage. Using a known flavivirus inhibitor, the JEV replicon cell line was validated for antiviral screening. The JEV replicon cell line will be a valuable tool for both compound screening and viral replication studies.