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The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a serious global health threat.This raises an urgent need for the devel-opment of effective drugs against the deadly disease.SARS-CoV-2 non-structural protein 14 (NSP14)carrying RNA cap guanine N7-methyltransferase and 3'-5'exoribonuclease activities could be a potential drug target for intervention.NSP14 of SARS-CoV-2 shares 98.7％ of similarity with the one (PDB 5NFY) of acute respiratory syndrome (SARS) by ClustalW.Then,the SARS-CoV-2 NSP14 structures were modelled by Modeller 9.18 using SARS NSP14 (PDB 5NFY) as template for virtual screening.Based on the docking score from AutoDock Vina1.1.2,18 small molecule drugs were selected for further evaluation.Based on the 5 ns MD simulation trajectory,binding free energy (AG) was calculated by MM/GBSA method.The calculated binding free energies of Saquinavir,Hypericin,Baicalein and Bromocriptine for the N-terminus of the homology model were-37.2711 ± 3.2160,-30.1746 ± 3.1914,-23.8953 ± 4.4800,and-34.1350 ± 4.3683 kcal/mol,respectively,while the calculated binding free energies were-60.2757 ± 4.7708,-30.9955 ± 2.9975,-46.3099 ± 3.5689,and-59.8104 ± 3.5389 kcal/mol,respectively,when binding to the C-terminus.Thus,the compounds including Saquinavir,Hypericin,Baicalein and Bromocriptine could bind to the N-terminus and C-terminus of the homology model of the SARS-CoV-2 NSP14,providing a candidate drug against SARS-CoV-2 for further study.
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Coronaviruses are a type of positive-sense single-stranded RNA virus with envelope and widely exist in nature to cause respiratory infectious diseases. The novel coronavirus is a new outbreak virus that is susceptible to all people. Up to now, the disease has been widely spread in the world and poses a great threat to public health. In this review, the genomic features, key proteins, host infection and replication of coronaviruses and novel coronaviruses are reviewed in order to provide theoretical basis for the study of the pathogenic mechanism of virus infection on host cells and to provide basic support for the development of specific antiviral drugs.
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Humanos , Betacoronavirus/fisiología , COVID-19 , Infecciones por Coronavirus/virología , Pandemias , Neumonía Viral/virología , SARS-CoV-2 , Replicación ViralRESUMEN
Objective@#To express the NS6 nonstructural protein of human norovirus (NoV) in Escherichia coli, and to detect its enzymatic activity after purification.@*Methods@#Human NoV NS6 gene was cloned into the prokaryotic expression vector pDE1 and then was transformed into E. coli BL21 for expression. NS6 protein was purified by Ni-NTA affinity chromatography and Superdex 200 pg column. The activity of NS6 protein was determined by digestion of fusion protein 15VP1-6P at 37 ℃.@*Results@#Human NoV NS6 protein was stably and highly expressed in E. coli. After purification, the expressed product reached a purity of more than 95%, and the relative molecular weight of NS6 protein was about 23×103 Da. NS6 protein could cleave the fusion protein containing rhinovirus 3C cleavage site.@*Conclusions@#The nonstructural protein NS6 of human NoV was successfully expressed in Escherichia coli, which laid a foundation for further study on the pathogenesis of human NoV.
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Objective@#To study the construction and humoral immunogenicity of the recombinant plasmids encoding nonstructural proteins(NSs) of severe fever with thrombocytopenia syndrome(SFTS) virus(SFTSV).@*Methods@#Recombinant plasmids encoding NSs gene and optimized NSs gene of SFTSV were constructed by polymerase chain reaction(PCR) and cloned into eukaryotic expression vector pJW4303, which were named pJW4303-NSs and pJW4303-NSs-opt, respectively. Then, the plasmid pJW4303-NSs was tagged with Flag, named pJW4303-NSs-Flag. Meanwhile, Nhe I restrict site and tissue plasminogen activator(tPA) signal sequence were inserted to construct bi-optimized recombinant plasmid named pJW4303-tPA-NSs-opt. All plasmids were identified by sequencing. The transient expression of NSs was confirmed by Western blotting in human embryonic kidney 293T cells. The NSs-specific IgG antibodies in BALB/c mice which were immunized by intramuscular injection with electroporation were examined by enzyme-linked immunosorbent assay(ELISA).@*Results@#The recombinant plasmids pJW4303-NSs, pJW4303-NSs-opt, pJW4303-tPA-NSs-opt and pJW4303-NSs-Flag were successfully constructed. The expression of NSs was confirmed in lysates and supernatants of 293T cells. The NSs-specific IgG responses of all three recombinant plasmids were detected by ELISA in BALB/c mice. It was found that optimized recombinant plasmid pJW4303-NSs-opt elicited higher levels of the NSs-specific IgG than that of pJW4303-NSs in week 6, 8 which induced stronger immune response.@*Conclusions@#The recombinant plasmids encoding SFTSV NSs possess the satisfied immunogenicity. In addition, the plasmid pJW4303-NSs-opt could induce the strongest humoral immune response.
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Objective@#To investigate the role of hepatitis C virus nonstructural protein 5A (NS5A) and its domains I, II, and III in regulating gluconeogenesis in mice and the underlying mechanism.@*Methods@#A total of 60 male C57BL/6J mice were randomly divided into six groups. Recombinant lentiviral particles with specific expression of full-length NS5A, NS5A domain I, NS5A domain II, or NS5A domain III were injected via the caudal vein to establish a mouse model, and the group without injection and the group with the injection of the lentiviral particles containing enhanced green fluorescent protein (EGFP) were established as negative control. The effect of full-length NS5A protein and its domains on fasting blood glucose (FBG) and fasting serum insulin (FINS) were measured. Liver tissue was collected to prepare a paraffin section. Immunohistochemistry was used to measure the expression of phosphoenolpyruvate carboxykinase (PEPCK) in hepatocytes, quantitative real-time PCR and/or Western blot were used to measure the expression of NS5A, phosphorylated adenosine monophosphate-activated protein kinase (p-AMPK), sterol regulatory element-binding protein-1 (SREBP-1), and PEPCK.@*Results@#Compared with the group without injection and the group with the injection of the lentiviral particles containing EGFP, the groups with the injection of the lentiviral particles containing full-length NS5A and NS5A domain II had significant increases in FBG and homeostasis model assessment of insulin resistance index (P < 0.01). Immunohistochemistry and quantitative real-time PCR showed a significant increase in the expression of PEPCK, a key enzyme involved in gluconeogenesis. Western blot showed that full-length NS5A protein and NS5A domain II inhibited the level of p-AMPK and increased the levels of SREBP-1 and PEPCK.@*Conclusion@#NS5A protein and NS5A domain II may affect glucose metabolism in hepatocytes in mice by regulating AMPK/SREBP-1/PEPCK, and NS5A domain II may play an important role in insulin resistance in hepatocytes caused by HCV infection.
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Norovirus (NoV), a single stranded RNA virus, is the major causative agent of the global acute gastroenteritis in humans, and it has drawn more and more attention. Because of the lack of appropriate animal models and in vitro cell culture models, people have studied and understood more about the epidemiology and genetic variation of human viruses. The functional characteristics of the viral encoded protein and the pathogenesis of virus infection are poorly understood. In this paper, we summarize the progress in studies on characteristics of non-structural protein of norovirus, and hope that with the recent breakthrough in human cell culture model of human norovirus, it can be used as a tool for further research on the function of human norovirus non-structural protein.
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Porcine epidemic diarrhea virus (PEDV) inhibits the host typeⅠinterferon and cellular antiviral response, but its inhibition mechanism is unclear, and the roles of PEDV nonstructural proteins in regulating typeⅠinterferon responses have been seldom studied. To study the effect of nsp1 on typeⅠinterferon response, nsp1 gene was cloned into a eukaryotic expression vector pCAGGS. The expression of nsp1 in transfected cells was determined by Western blot and indirect immunofluorescence assay. The effects of nsp1 on the induction of typeⅠinterferon were evaluated by dual luciferase reporter gene assay, ELISA and VSV bioassay. Western blot and indirect immunofluorescence assay showed that nsp1 was highly expressed in transfected cells and PEDV-infected cells. Dual luciferase reporter gene assay results indicated that nsp1 strongly inhibited the IFN-β promoter activity, and the inhibitory effect was nsp1 dose-dependent. ELISA results showed that nsp1 significantly inhibited the expression of IFN-β in protein level. And VSV replication-inhibition bioassay revealed that nsp1 significantly inhibited typeⅠIFN antiviral activities induced by poly(I:C). Our results implied that nsp1 was a highly conserved protein of PEDV and exhibited antagonistic function on interferon promoter activity. The results have laid a foundation for further understanding the immune evasion mechanism of PEDV and for developing new effective vaccine against PEDV.
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Rotavirus is the most important pathogen causing severe diarrhea in infants and young children worldwide,and for rotavirus diarrhea there is no specific treatment so far.At present,there are a variety of claims on the pathogenesis of rotavirus infection,but none is conclusive.In the process of infection,rotavirus pathogens must overcome antiviral innate immune response that can replicate in host cell.Rotavirus encoded proteins play an important role in the process of rotavirus infection.This paperreviews the role of rotavirus encoding proteins in the pathogenesis of rotavirus infection.
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Since there is no specific symptoms after human have been infected by parvovirus,parvovirus was administered as a potential cancer therapeutics.Parvovirus was employed as an effective treatment in glioblastoma multiforme,Burkitt' s lymphoma,liver cancer,pancreatic carcinoma,breast cancer and colon cancer.Anti-tumor effects of parvovirus were approved to be associated with its oncolytic effects,non-structural protein 1 and immunoregulation.
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Objective To construct prokaryotic expression systems of genes of intact rotavirus non -structural protein 4 (NSP4) and 86 to 175 amino acid peptide of NSP4 (NSP486-175) and to identify the bio-activities of the recombinant expression products .Methods Colloidal gold assay was used to screen group A rotavirus antibody-positive stools , from which the viral RNA was extracted and transcribed into cDNA .Then NSP4 gene and NSP486-175 gene were amplified by PCR and inserted into pET-28a(+) vector to construct the prokaryotic expression plasmids of pET-28a(+)-NSP4 and pET-28a(+)-NSP486-175 , which were transformed into E.coli BL21( DE3) and inducted by IPTG .The expressed NSP486-175 protein was purified by Ni-NTA af-finity chromatography and examined by Western blot .Fluo-3 AM ester was used to label intracellular free Ca2+( [ Ca2+] i) in Caco-2 cells and laser scanning confocal microscopy was performed to detect the effect of NSP486-175 protein on [Ca2+]i.Results DNA sequencing indicated that NSP4 gene and NSP486-175 gene were consistent with the corresponding sequences in NCBI .The intact NSP4 had difficulty in expressing in E.coli. NSP486-175 protein mainly existed in soluble form with a relative molecular weight of 10×103 .Fluorescence in-tensity and distribution were changed by exogenous addition of NSP 486-175 to cultured Caco-2 cells.Conclu-sion The expression vectors of pET-28a(+)-NSP4 and pET-28a(+)-NSP486-175 were successfully construc-ted and the target protein could induce [Ca2+]i imbalance.This phenomenon preliminarily indicates that the prokaryotic expressed NSP486-175 protein has biological activity and can be further used to elucidate rotavirus pathogenic mechanisms and perform vaccine research .
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Fourteen H9N2 avian influenza viruses (AIV) were isolated from sick chickens in China from 1998 to 2008. The sequences of the Non-structural(NS) gene of these isolates were determined by RT-PCR and sequencing, and the entire ORF sequences of NS1 and NS2 protein were obtained.-The homology of these nucleotide sequences and the putative amino acid sequences were compared with several classic reference viruses of H9N2. These isolates were proved to be highly homologous in NS gene (92.9%-99.9% identity) and all belonged to A/Chicken/Beijing/1/1994-like group in the Asia bird-swine branch of allele A of HS gene phylogenetic tree.-According to this study and previous reports of other researchers, NS gene of H9N2 subtype AIV in chickens of China is genetically stable and there is no enough evidence to support the establishment of other sub-lineages in chickens.
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Objective To develop a capture enzyme-linked immunosorbent assay (ELISA) for influenza A virus nonstructural protein NS1 using two anti-NS1 monoclonal antibodies(McAb) that map to distinct sites on the protein and to detect the NS1 in the culture supernatant and cell lysis supernatant of influenza virus. Methods Among the McAb against influenza A virus NS1, antibody pairs were analyzed to choose the optimal coating McAb and detecting McAb by determinating the detection sensitivity and specificity. Results The capture ELISA efficiently detected as little as 240 pg/ml of recombinant NS1 protein and exhibited no cross-reactivity for influenza B virus, parainfluenza virus NS1. Conclusion A sensitive and specific NS1-based capture ELISA for influenza A virus NS1 was successfully established, which could be an important tool for diagnosis of influenza A virus infection.
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Avian influenza (AI) virus infects both animal and human. Low pathogenic AI virus infections (some H7 and H9 subtypes) have been reported all over the world and pose a potential threat to the poultry industry. Vaccination is the most effective way to prevent virus infection. However, vaccination makes it difficult to differentiate between vaccinated chickens and infected chickens. In order to differentiate vaccinated chickens from naturally infected chickens, we adopted synthetic peptide-based enzyme-linked immunosorbent assay (ELISA) using the peptide sequences from nonstructural protein 1 (NS1) of H9N2. Five synthetic peptides were designed using Protein Variability Sever (http://imed.med.ucm.es/PVS/) and synthesized. NS1-1 ~ NS1-4 peptides failed to detect serum antibodies from both vaccinated and naturally infected chickens. NS1-5 peptide from the C-terminal NS1 protein detected serum antibody from naturally infected chickens but not vaccinated chickens. These results imply that NS1-5 peptide may be a useful tool to differentiate naturally infected chicken from vaccinated chicken as being used in the synthetic peptide-based ELISA.
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Animales , Humanos , Anticuerpos , Pollos , Ensayo de Inmunoadsorción Enzimática , Gripe Aviar , Péptidos , Aves de Corral , Vacunación , VirusRESUMEN
Viral nonstructural proteins in both enveloped and non-enveloped viruses play important roles in viral replication. Protein NS38 of Grass carp reovirus (GCRV), has been deduced to be a non-structural protein, and, consistent with other reoviruses, is considered to cooperate with the NS80 protein in viral particle assembly. To investigate the molecular basis of the role of NS38, a complete protein was expressed in E.coli for the first time. It was found that there is a better expression of NS38 induced with IPTG at 28 ℃ rather than 37 ℃. In addition, the antiserum of NS38 prepared with purified fusion protein and injected into rabbit could be used for detecting NS38 protein expression in GCRV infected cell lysate, while there is not any reaction crossed with purified virus particle, confirming NS38 is not a component of the viral structural protein. The result reported in this study will provide evidence for further viral protein-protein and protein-RNA interaction in dsRNA viruses replication.
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Genome replication of reovirus occurs in cytoplasmic inclusion bodies called viral factories or viroplasms. The viral nonstructural protein μNS, encoded by genome segment M3, is not a component of mature virions, but is expressed to high levels in infected cells and is concentrated in the infected cell factory matrix. Recent studies have demonstrated that μNS plays a central role in forming the matrix of these structures, as well as in recruiting other components to them for putative roles in genome replication and particle assembly.
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Grass carp reovirus (GCRV), a double stranded RNA virus that infects aquatic animals, often with disastrous effects, belongs to the genus Aquareovirus and family Reoviridea. Similar to other reoviruses, genome replication of GCRV in infected cells occurs in cytoplasmic inclusion bodies, also called viral factories. Sequences analysis revealed the nonstructural protein NS80, encoded by GCRV segment 4, has a high similarity with uNS in MRV(Mammalian orthoreoviruses), which may be associated with viral factory formation. To understand the function of the uNS80 protein in virus replication, the initial expression and identification of the immunogenicity of the GCRV NS80 protein inclusion forming-related region (335.742) was investigated in this study. It is shown that the over-expressed fusion protein was produced by inducing with IPTG at 28oC. In addition, serum specific rabbit antibody was obtained by using super purified recombinant NS80(335.742) protein as antigen. Moreover, the expressed protein was able to bind to anti-his-tag monoclonal antibody (mouse) and NS80(335-742) specific rabbit antibody. Further western blot analysis indicates that the antiserum could detect NS80 or NS80C protein expression in GCRV infected cells. This data provides a foundation for further investigation of the role of NS80 in viral inclusion formation and virion assembly.
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Abnormal cell signal transduction is associated with the occurrence and development of human diseases. Some virus pathogenicity and infection mechanism are due to virus antigen protein acting on the host cell signal transduction pathway, leading to host cell signal transduction disorder. Hepatitis C virus (HCV) is a major pathogen of chronic hepatitis C, which causes cirrhosis and hepatocellular carcinoma. But the pathogenesis of HCV and persistent infection mechanism remain far from clear. HCV pathogenesis may be related to the HCV protein expression interfering host cell signal transduction pathways. The studies of hepatitis C virus proteins acting on host cell signal transduction pathways, not only help to clarify the impact of its pathogenic mechanisms, but also benefit to new drug design and development for new treatment methods. This article summarizes the recent progress in research on the effect of hepatitis C virus protein in cell signal transduction pathways in the past few years.
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The first research on the NS1 protein as the non-structural protein of the type A influenza virus was emphasized on the considering of its depressant effect on the composition of the protein of host cell.And now,with deep research,the evolution of its genes and the antigenicity of its protein have been explained.The NS1 protein of influenza virus has the association with the apoptosis induced by the influenza virus,the regulating function of apoptosis has the direct correlation with possibility of producing interference and the cell line infected by influenza virus.The NS1 protein restrained to producing the interferon by infected cell.The NS1 protein plays an important role on the host anti-viral cytokine responses,it possesses nagitive regulation for interferon's antiviral activity,most observation indicated nagitive regulation might associate with the virulence of influenza virus.Furthermore NS1 protein as an inspection antigen to differentiate and diagnose the poultry which was immunized or naturally infected has a very wide prospect,because the traditional vaccine was used extensively.
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It was reported that the sera of convalescent animals contain antibodies to foot and mouth disease (FMD) virus (FMDV) 2C, highly conserved nonstructural protein (NSP), whereas the sera of vaccinated animals do not. But ELISA methods using this protein were not reported and developed until recently. In this study, NSP 2C peptides were synthesized within the amino acid sequence of the conserved 2C nonstructural region of FMDV according to the sequences from Genbank database and used for identifying antigenic determinants. One of the synthesized thirteen peptides gave strong positive reactivity with most of the sera from 13 FMD infected farms, but not with sera from vaccinated and non-infected animals. Moreover, with the sera collected through serial bleedings from four cattle and five goats infected with FMDV O/SKR/2000 experimentally, positive results were obtained in two species after 10 days post infection (DPI). Therefore, we tried to develop and evaluate this ELISA based on 2C peptides. In comparison with the commercial NSP ELISA, the 2C peptide based ELISA method showed good specificity and sensitivity. These results demonstrate that the synthetic 2C peptide ELISA can be a complementary marker to differentiate FMDV-infected from vaccinated on a herd basis.
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Animales , Bovinos , Ensayo de Inmunoadsorción Enzimática/veterinaria , Fiebre Aftosa/diagnóstico , Virus de la Fiebre Aftosa , Cabras , Sensibilidad y Especificidad , Vacunación , Proteínas no Estructurales Virales/síntesis química , Vacunas ViralesRESUMEN
Objective To construct and expr es s a recombinant plasmid of nonstructural protein NS3-NS4 of hepatitis C virus ( HCV), and to identify the antigenicity of the expressed protein. Methods A gene region encompassing the nonstructural protei n NS3-NS4 of HCV was amplified by polymerase chain reaction (PCR) from the pUC1 9/HCV template. The recombinant expression plasmid containing the pBV220/NS3-NS 4 sequence was constructed, and the nonfused NS3-NS4 recombinant protein was ex pressed in E.coli DH5? efficiently. The recombinant protein was det ected by SDS-PAGE and ELISA. Results We successfully constructed and expressed the recom binant plasmid in prokaryote. Its antigenicity was detected with 50 standard ser a. Compared with the second-generation diagnostic Kit, the total detection rate was 96%. Conclusion The whole NS3-NS4 protein, a region of dominant immunogenicity, should be the effective component of the HCV diagnostic Kit and provide the clue for developing HCV DNA vaccine.