Epstein-Barr virus envelope glycoprotein 110 inhibits NF-κB activation by interacting with NF-κB subunit p65.

Epstein-Barr virus (EBV) is a member of the lymphotropic virus family and is highly correlated with some human malignant tumors. It has been reported that envelope glycoprotein 110 (gp110) plays an essential role in viral fusion, DNA replication, and nucleocapsid assembly of EBV. However, it has not been established whether gp110 is involved in regulating the host's innate immunity. In this study, we found that gp110 inhibits tumor necrosis factor α-mediated NF- κB promoter activity and the downstream production of NF- κB-regulated cytokines under physiological conditions. Using dual-luciferase reporter assays, we showed that gp110 might impede the NF-κB promoter activation downstream of NF-κB transactivational subunit p65. Subsequently, we used coimmunoprecipitation assays to demonstrate that gp110 interacts with p65 during EBV lytic infection, and that the C-terminal cytoplasmic region of gp110 is the key interaction domain with p65. Furthermore, we determined that gp110 can bind to the N-terminal Rel homologous and C-terminal domains of p65. Alternatively, gp110 might not disturb the association of p65 with nontransactivational subunit p50, but we showed it restrains activational phosphorylation (at Ser536) and nuclear translocation of p65, which we also found to be executed by the C-terminal cytoplasmic region of gp110. Altogether, these data suggest that the surface protein gp110 may be a vital component for EBV to antagonize the host's innate immune response, which is also helpful for revealing the infectivity and pathogenesis of EBV.

Post-doping induced morphology evolution boosts Mn2+ luminescence in the Cs2NaBiCl6:Mn2+ phosphor.

As we know, defects caused in the synthetic process of metal halide perovskite are the most difficult to overcome, and greatly limit their photoelectric performances. Herein, a post-doped strategy was utilized to achieve an interesting morphology evolution from a standard octahedron to a snowflake-like sheet during the Mn2+-doped Cs2NaBiCl6 process, which realizes the obvious photoluminescence quantum efficiency (PLQY) enhancement of the Cs2NaBiCl6:Mn2+ phosphor. This surprising evolution is ascribed to the morphology collapse and reconstruction induced by Mn2+ exchange. The obtained phosphor exhibits enhanced 31.56% PLQY, which is two-fold higher than that synthesized by the traditional co-precipitation method, with broad emission spectrum and good PL color stability at 150 °C. Combined with the Cs2SnCl6 : 1mol%Bi3+ phosphor to fabricate the phosphor-converted light-emitting diode, bright white light emission with Ra = 88, CCT = 4320 K, CIE (0.36, 0.33) and a good application potential in high-resolution PL imaging agents was obtained. This work provides a possible effective strategy to improve the PL performance for impurity-doped lead-free metal halide perovskite.

Highly Stable Orange-Red Long-Persistent Luminescent CsCdCl3 :Mn2+ Perovskite Crystal.

Halide perovskite has been widely studied as a new generation of photoelectronic materials. However, their thermal and humidity-induced emission quenching have greatly limited their utility and reliability. Here, we report a hexagonal Mn2+ -doped CsCdCl3 perovskite crystal that possesses stable photoluminescence (PL) at both high temperature and humidity. The room temperature long-persistent luminescence (LPL) of the single crystals lasts up to 1480 s and can be adjusted by changing the concentration of Mn2+ ion doping. The characteristic emission of d-d transition of Mn2+ is realized, and the photoluminescence quantum yield (PLQY) is up to 91.4 %, it can maintain more than 90 % of the initial PL spectral integral area at 150 °C (423 K). High humid stability PL can be achieved more than 75 % of the initial PL intensity after 55 days of immersion in water. These excellent properties show the application prospect of the LPL material in lighting indication and anti-counterfeiting.

Enhancing Structural Rigidity via a Strategy Involving Protons for Creating Water-Resistant Mn4+-Doped Fluoride Phosphors.

The poor water resistance property of a commercial Mn4+-activated narrow-band red-emitting fluoride phosphor restricts its promising applications in high-performance white LEDs and wide-gamut displays. Herein, we develop a structural rigidity-enhancing strategy using a novel KHF2:Mn4+ precursor as a Mn source to construct a proton-containing water-resistant phosphor K2(H)TiF6:Mn4+ (KHTFM). The parasitic [HMnF6]- complexes in the interstitial site from the fall off the KHF2:Mn4+ are also transferred to the K2TiF6 host by ion exchange to form KHTFM with rigid bonding networks, improving the water resistance and thermostability of the sample. The KHTFM sample retains at least 92% of the original emission value after 180 min of water immersion, while the non-water-resistant K2TiF6:Mn4+(KTFM) phosphor maintains only 23%. Therefore, these findings not only illustrate the effect of protons on fluoride but also provide a novel insight into commercial water-resistant fluoride phosphors.

Novel Cyan-Green-Emitting Bi3+-Doped BaScO2F, R+ (R = Na, K, Rb) Perovskite Used for Achieving Full-Visible-Spectrum LED Lighting.

Cyan-emitting phosphors are important for near-ultraviolet (NUV) light-emitting diodes (LEDs) to gain high-quality white lighting. In the present work, a Bi3+-doped BaScO2F, R+ (R = Na, K, Rb) perovskite, which emits 506 nm cyan-green light under 360 or 415 nm excitation, is obtained via a high-temperature solid-state method for the first time. The obtained perovskite shows improved photoluminescence and thermal stability due to the charge compensation of Na+, K+, and Rb+ co-doping. Its spectral broadening is attributed to two centers Bi (1) and Bi (2), which are caused by the zone-boundary octahedral tilting due to the substitution of Bi3+ for the larger Ba2+. Employing the blend phosphors of Ba0.998ScO2F:0.001Bi3+,0.001K+ and the commercial BAM:Eu2+, YAG:Ce3+, and CaAlSiN3:Eu2+, a full-spectrum white LED device with Ra = 96 and CCT = 4434 K was fabricated with a 360 nm NUV chip. Interestingly, a novel strategy is proposed: the cyan-green Ba0.998ScO2F:0.001Bi3+,0.001K+ and orange Sr3SiO5:Eu2+ phosphors were packaged with a 415 nm NUV chip to produce the white LED with Ra = 85 and CCT = 4811 K.

Intracellular distribution of pseudorabies virus UL2 and detection of its nuclear import mechanism.

Pseudorabies virus (PRV) UL2 (pUL2) is a multifunctional protein, which is homologous with herpes simplex virus 1 early protein UL2 (hUL2) and crucial for the viral propagation. Yet, how pUL2 executes its roles in the viral life cycle remain inadequately understood. In order to uncover its effect on the procedure of PRV infection, investigation was performed to examine the subcellular distribution of pUL2 and establish its trafficking mechanism. In the present study, enhanced yellow fluorescent protein or Myc tag fused pUL2 was transiently overexpressed in transfected cells and exhibited an absolutely nuclear accumulation without the existence of other PRV proteins. Additionally, the nuclear trafficking of pUL2 was proved to rely on Ran-, transportin-1, importin ß1, importin α1, α3 and α5. Accordingly, these data will benefit the knowledge of pUL2-mediated biological effects in PRV infection cycle.

Epstein-Barr virus tegument protein BGLF2 inhibits NF-κB activity by preventing p65 Ser536 phosphorylation.

Epstein-Barr virus (EBV), a ubiquitous gammaherpesvirus, can regulate the antiviral response of NF-κB signaling, which is critical for cell survival, growth transformation, and virus latency. Here, we showed that tegument protein BGLF2 could inhibit TNF-α-induced NF-κB activity. BGLF2 was shown to interplay with the NF-κB subunits p65 and p50, and the Rel homology domain of p65 was the pivotal region to interact with BGLF2. Nonetheless, BGLF2 did not influence the development of p65-p50 dimerization. Yet, overexpression of BGLF2 inhibited the phosphorylation of p65 Ser536 (but not Ser276) and blocked the nuclear translocation of p65. In addition, knockdown of BGLF2 during EBV lytic replication elevated NF-κB activity and the phosphorylation of p65 Ser536. Taken together, these results suggest that the inhibition of NF-κB activation may serve as a strategy to escape the host's antiviral innate immunity to EBV during its lytic infection.-Chen, T., Wang, Y., Xu, Z., Zou, X., Wang, P., Ou, X., Li, Y., Peng, T., Chen, D., Li, M., Cai, M. Epstein-Barr virus tegument protein BGLF2 inhibits NF-κB activity by preventing p65 Ser536 phosphorylation.

Phase Transformation of a K2GeF6 Polymorph for Phosphors Driven by a Simple Precipitation-Dissolution Equilibrium and Ion Exchange.

Tuning crystal phase transformations is very important for obtaining polymorphs for phosphors with the ideal optical properties and stability. Mn4+-doped K2GeF6 (KGF) is a typical polymorphic phosphor, but the thermodynamic and kinetic mechanism of its phase transformation is still unclear. Herein, the phase transformation of polymorphs varying from P63mc KGF and trigonal KGF to P63mc Si4+-doped KGF is realized by introducing the synergistic action of an HF solution and Si4+ ions. The full structural refinements of KGF polymorphs at room temperature and the electronic band structure calculations were performed. The results show that the Si4+-doped hexagonal KGF polymorph with good photoluminescence properties is the most stable phase according to the calculated total energy landscape and relative formation energy. The morphologic changes were monitored in situ to clearly understand the rapid phase transformation mechanism, which proves that the phase transformation is driven by a simple precipitation-dissolution equilibrium and ionic exchange.

Identification of the molecular determinants for nuclear import of PRV EP0.

Pseudorabies virus (PRV) early protein EP0 is a homologue of the herpes simplex virus 1 (HSV-1) immediate-early protein ICP0, which is a multifunctional protein and important for HSV-1 infection. However, the definite function of EP0 during PRV infection is not clear. In this study, to determine if EP0 might localize to the nucleus, as it is shown for its homologue in HSV-1, the subcellular localization pattern and molecular determinants for the nuclear import of EP0 were investigated. EP0 was demonstrated to predominantly target the nucleus in both PRV infected- and plasmid-transfected cells. Furthermore, the nuclear import of EP0 was shown to be dependent on the Ran-, importin α1-, α3-, α7-, ß1- and transportin-1-mediated multiple pathways. Taken together, these data will open up new horizons for portraying the biological roles of EP0 in the course of PRV lytic cycle.

Molecular evolutionary and antigenic characteristics of newly isolated H9N2 avian influenza viruses in Guangdong province, China.

Four new H9N2 avian influenza viruses (AIVs) were isolated from domestic birds in Guangdong between December 2015 and April 2016. Nucleotide sequence comparisons indicated that most of the internal genes of these four strains were highly similar to those of human H7N9 viruses. Amino acid substitutions and deletions found in the HA and NA proteins indicated that all four of these new isolates may have an enhanced ability to infect humans and other mammals. A cross-hemagglutinin-inhibition assay, conducted with two vaccine strains that are broadly used in China, suggested that antisera against vaccine candidates could not provide complete inhibition of the new isolates.

Characterization of the Nucleocytoplasmic Transport Mechanisms of Epstein-Barr Virus BFLF2.

BACKGROUND/AIMS: Epstein-Barr virus (EBV) BFLF2, the homologue of herpes simplex virus 1 (HSV-1) UL31, is crucial for the efficient viral DNA packaging and primary egress across the nuclear membrane. However, we still do not know its subcellular transport mechanisms. METHODS: Interspecies heterokaryon assays were utilized to detect the nucleocytoplasmic shuttling of BFLF2, and mutation analysis, plasmid transfection and fluorescence microscopy assays were performed to identify the functional nuclear localization sequence (NLS) and nuclear export sequence (NES) of BFLF2 in live cells. Furthermore, the nuclear import and export of BFLF2 were assessed by confocal microscopy, co-immunoprecipitation and immunoblot assays. RESULTS: BFLF2 was confirmed to shuttle between the nucleus and cytoplasm. Two predicted NESs were shown to be nonfunctional, yet we proved that the nuclear export of BFLF2 was mediated through transporter associated with antigen processing (TAP), but not chromosomal region maintenance 1 (CRM1) dependent pathway. Furthermore, one functional NLS, 22RRLMHPHHRNYTASKASAH40, was identified, and the aa22-23, aa22-25, aa28-30 and aa37-40 had an important role in the nuclear localization of BFLF2. Besides, the nuclear import of BFLF2 was demonstrated through Ran-, importin α7-, importin ß1- and transportin-1-dependent mechanism that does not require importin α1, α3 and α5. CONCLUSION: These works are of significance for the further study of the functions of BFLF2 during EBV infection, as well as for further insights into the design of new antiviral drug target and vaccine development against EBV.

Characterization of the subcellular localization and nuclear import molecular mechanisms of herpes simplex virus 1 UL2.

As a crucial protein, the herpes simplex virus 1 (HSV-1) UL2 protein has been shown to take part in various stages of viral infection, nonetheless, its exact subcellular localization and transport molecular determinants are not well known thus far. In the present study, by using live cells fluorescent microscopy assay, UL2 tagged with enhanced yellow fluorescent protein was transiently expressed in live cells and showed a completely nuclear accumulation without the presence of other HSV-1 proteins. Moreover, the nuclear transport of UL2 was characterized to be assisted by multiple transport pathways through Ran-, importin α1-, α5-, α7-, ß1- and transportin-1 cellular transport receptors. Consequently, these results will improve understanding of UL2-mediated biological functions in HSV-1 infection cycles.

Characterization of the nuclear import mechanisms of HSV-1 UL31.

As an important protein, UL31 has been demonstrated to play multiple roles in herpes simplex virus 1 (HSV-1) replication. Previous studies showed that UL31 predominantly locates in the nucleus in chemical fixed cells and live cells, however, the determining mechanisms for its nuclear translocation is not clear. In the present study, by utilizing live cells fluorescent microscopy and co-immunoprecipitation assays, the nuclear import of UL31 was characterized to be dependent on Ran-, importin α1- and transportin-1-mediated pathway. Therefore, these results will promote the understanding of UL31-mediated biological functions in HSV-1 infection cycle.

Characterization of the nuclear import signal of herpes simplex virus 1 UL31.

The herpes simplex virus 1 (HSV-1) UL31 protein is a multifunctional nucleoprotein that is important for viral infection; however, little is known concerning its subcellular localization signal. Here, by transfection with a series of HSV-1 UL31 deletion mutants fused to enhanced yellow fluorescent protein (EYFP), a bipartite nuclear localization signal (NLS) was identified and mapped to amino acids (aa) 1 to 27 (MYDTDPHRRGSRPGPYHGKERRRSRSS). Additionally, fluorescence results showed that the predicted nuclear export signal (NES) might be nonfunctional, and the functional NES of UL31 might require a specific conformation. Taken together, these results would provide significant information for the study of the biological function of UL31 during HSV-1 infection.

Herpes simplex virus 1 counteracts viperin via its virion host shutoff protein UL41.

The interferon (IFN)-inducible viperin protein restricts a broad range of viruses. However, whether viperin plays a role during herpes simplex virus 1 (HSV-1) infection is poorly understood. In the present study, it was shown for the first time that wild-type (WT) HSV-1 infection couldn't induce viperin production, and ectopically expressed viperin inhibited the replication of UL41-null HSV-1 but not WT viruses. The underlying molecular mechanism is that UL41 counteracts viperin's antiviral activity by reducing its mRNA accumulation.

Identification of molecular determinants for the nuclear import of pseudorabies virus UL31.

Herpes simplex virus 1 (HSV-1) UL31 is a multifunctional protein and important for HSV-1 infection. Pseudorabies virus (PRV) UL31 is a late protein homologous to HSV-1 UL31. Previous studies showed that PRV UL31 is predominantly localized to nucleus, however, the molecular determinants for its nuclear import were unclear to date. Here, by utilizing live cells fluorescent microscopy, UL31 fused with enhanced yellow fluorescent protein was transiently expressed in live cells and confirmed to exclusively target to the nucleus in the absence of other viral proteins. Furthermore, the nuclear import of UL31 was found to be dependent on the Ran-, importin α1-, α3-, α5-, α7-, ß1-and transportin-1-mediated pathway. Therefore, these results would open up new avenues for depicting the biological functions of UL31 during PRV infection.

Characterization of the nuclear import and export signals of pseudorabies virus UL31.

The pseudorabies virus (PRV) UL31 protein (pUL31) is a homologue of the herpes simplex virus 1 pUL31, which is a multifunctional protein that is important for HSV-1 infection. However, little is known concerning the subcellular localization signal of PRV UL31. Here, by transfection with a series of PRV UL31 deletion mutants fused to an enhanced yellow fluorescent protein (EYFP) gene, a bipartite nuclear localization signal (NLS) and a PY motif NLS of UL31 were identified and mapped to amino acids (aa) 4 to 20 (RRRLLRRKSSAARRKTL) and aa 21 to 34 (TRAARDRYAPYFAY), respectively. Additionally, the predicted nuclear export signal (NES) was shown to be nonfunctional. Taken together, this information opens up new avenues for investigating the biological functions of UL31 during PRV infection.

Cloning, expression, purification, antiserum preparation and its characteristics of the truncated UL6 protein of herpes simplex virus 1.

The herpes simplex virus 1 (HSV-1) portal protein UL6 is important for HSV-1 replication, however, its precise functions in the virus life cycle are poorly understood. As we known, a relatively important tool for disclosing these functions is the antiserum specifically detecting UL6 in the HSV-1-infected cell. To this end, a recombinant protein consisting of C-terminal 297-676 amino acids of UL6 fused to His-tag was expressed in E. coli and purified from inclusion body by the Ni(2+)-NTA affinity chromatography under denaturing conditions, which was then refolded and used for the preparation of antiserum in rabbit. As results, western blot and immunofluorescence assay showed that this antiserum could specifically detect the purified truncated UL6 as well as native UL6 in the HSV-1 infected cells, indicating that the prepared antiserum could serve as a valuable tool for further exploring the functions of UL6.

Molecular cloning and characterization of pseudorabies virus EP0 gene.

The pseudorabies virus (PRV) early protein EP0 is a homologue of the herpes simplex virus 1 (HSV-1) immediate-early protein ICP0, which is a multifunctional protein and important for HSV-1 infection. However, the exact function of EP0 is not clear. In this study, using polymerase chain reaction, a 1,104 base-pair sequence of the EP0 gene was amplified from the PRV Becker strain genome and identification of the EP0gene was confirmed by further cloning and sequencing. Bioinformatics analysis indicated that the PRV EP0 gene encoded a putative polypeptide with 367 amino acids. The encoded protein, designated as EP0 contained a conserved RING-finger superfamily domain and was found to be closely related with the herpes virus RING-finger superfamily and was highly conserved among the counterparts encoded by RING-finger genes. Multiple nucleic acid sequence and amino-acid sequence alignments suggested that PRV EP0 showed a relatively higher similarity with EP0-like proteins of genus Varicellovirus than with those of other genera of Alphaherpesvirinae. In addition, phylogenetic analysis showed that PRV EP0 had a close evolutionary relationship with members of genus Varicellovirus, especially bovine herpesvirus 1 (BoHV-1) and BoHV-5. Antigen prediction indicated that several potential B-cell epitopes were located in EP0. Also, subcellular localization analysis demonstrated that EP0 was predominantly localized in the nucleus, suggesting that it might function as a nuclear-targeted protein.

FTO alleviates cerebral ischemia/reperfusion-induced neuroinflammation by decreasing cGAS mRNA stability in an m6A-dependent manner.

Microglia-mediated inflammation is a major contributor to the brain damage in cerebral ischemia and reperfusion (I/R) injury, and N6-Methyladenosine (m6A) has been implicated in cerebral I/R injury. Here, we explored whether m6A modification is associated with microglia-mediated inflammation in cerebral I/R injury and its underlying regulatory mechanism using an in vivo mice model of intraluminal middle cerebral artery occlusion/reperfusion (MCAO/R) and in vitro models of primary isolated microglia and BV2 microglial cells subjected to oxygen-glucose deprivation and reoxygenation (OGD/R) were used. We found microglial m6A modification increased and microglial fat mass and obesity-associated protein (FTO) expression decreased in cerebral I/R injury in vivo and in vitro. Inhibition of m6A modification by intraperitoneal injection of Cycloleucine (Cyc) in vivo or transfection of FTO plasmid in vitro significantly alleviated brain injury and microglia-mediated inflammatory response. Through Methylated RNA immunoprecipitation sequencing (MeRIP-Seq), RNA sequencing (RNA-Seq) and western blotting, we found that m6A modification promoted cerebral I/R-induced microglial inflammation via increasing cGAS mRNA stability to aggravate Sting/NF-κB signaling. In conclusion, this study deepens our understanding on the relationship of m6A modification and microglia-mediated inflammation in cerebral I/R injury, and insights a novel m6A-based therapeutic for inhibiting inflammatory response against ischemic stroke.