Dengue virus non-structural 1 protein interacts with heterogeneous nuclear ribonucleoprotein H in human monocytic cells

Objective: To study protein-protein interaction between heterogeneous nuclear ribonucleoprotein H(hn RNP H) and Dengue virus(DENV) proteins. Methods: DENV proteins were screened against the host hn RNP H protein, in order to identify the host-viral protein-protein interactions in DENV infected THP-1 cells by co-immunoprecipitation. The co-localization of the interacting proteins was further confirmed by immunofluorescence microscopy. Results: The host protein hn RNP H was found to interact with DENV nonstructural 1 protein and help the virus to multiply in the cell. Conclusions: The non-structural 1 glycoprotein is a key modulator of host immune response and is also involved in viral replication. Therefore, disruption of this key interaction between hn RNP H and DENV nonstructural 1 could be an important therapeutic strategy for management of DENV infection.

Cleft analysis of Zika virus non-structural protein 1

The non-structural protein 1 is an important molecule of the viruses in flavivirus group including to Zika virus. Recently, the NS1 of Zika virus was discovered. There is still no complete information of the molecular interaction of NS1 of Zika virus which can be the clue for explanation for its pathogenesis and further drug search. Here the authors report the cleft analysis of NS1 of Zika virus and the result can be useful for future development of good diagnostic tool and antiviral drug finding for management of Zika virus.

The cloning of non-structural-1 (NS1) gene of H9N2 subtype of avian influenza virus in pGEX-4T-1 and pMAL-c2X plasmids and expression in <i>Escherichia coli</i>DH5<i>α</i>strain

Avian influenza is a viral contagious disease that affects poultry industry and human health. Vaccination has been considered as a preventive tool in the eradication of AI, but it causes some limitations including trade embargoes and interfering with serologic surveillance in differentiation between infected and vaccinated animals (DIVA strategy). Several distinct DIVA strategies have been presented to conquer these limitations. In this study, the open reading frame of NS1 gene of a H9N2 subtype of AI virus was amplified by polymerase chain reaction. After extraction and purification of NS1 gene from agarose gel, it was inserted into two different pGEX-4T-1 and pMAL-c2X plasmids and transferred in DH5α strain of Escherichia coli by using electroporation procedure. The E. coli colonies possessing recombinant NS1 gene were screened using PCR, restriction mapping and sequencing analysis. The expressed rNS1 protein was purified using affinity chromatography based on MBP (pMAL- c2X) and GST (pGEX-4T-1). The MBP-NS1 and GST- NS1 proteins on SDS-PAGE had bands with molecular weight of 68 and 52 kDa respectively. Western blotting with MBP-NS1 protein showed positive reaction using antisera obtained from chickens challenged with a H9N2 subtype strain. But, the most sera prepared from H9N2 vaccinated chickens were negative in WB. These findings indicated that the MBP-rNS1 protein of 26 kDa expressed by pMAL-c2X plasmid can be used in a DIVA for differentiation of AI infected and vaccinated chickens.

人星状病毒非结构蛋白nsP1a／1表达纯化及多克隆抗体的制备

目的：表达纯化人星状体病毒（ human astrovirus， HAstV）非结构蛋白nsP1a／1，免疫动物制备多克隆抗体。方法利用PCR技术扩增nsP1a／1基因序列，构建到大肠埃希菌原核表达系统中表达重组nsP1a／1蛋白，使用镍柱亲和层析法对重组蛋白进行纯化，十二烷基磺酸钠-聚丙烯酰胺凝胶电泳（ SDS-PAGE）和二噻啉甲酸（BCA）实验对重组蛋白的纯度与浓度进行分析，以重组的nsP1a／1蛋白为抗原，免疫雄性SPF级SD 大鼠获得多抗血清，用 ELISA 测定抗体效价、 Western 印迹检测抗体特异性。结果nsP1a／1-pET28a原核表达载体构建成功，将其转化至大肠埃希菌BL21（DE3）细菌中诱导表达了重组蛋白，免疫大鼠获得的多抗血清几何平均效价达到1∶406374。结论本实验成功地运用原核表达系统表达并鉴定了人星状体病毒非结构蛋白nsP1a／1，为进一步研究人星状病毒的复制及病毒感染的临床诊断奠定基础。

Structural insights into the distinct protective mechanisms of human antibodies targeting ZIKV NS1

Antibodies targeting non-structural protein 1(NS1)confer protection against Zika virus(ZIKV).Although monoclonal an-tibodies(MAbs)3G2 and 4B8 are more potent than MAb 4F10 in suppressing ZIKV infection in neonatal mice models,the epitopes are unclear.Herein,we determined the Cryo-electron microscopy(Cryo-EM)structures of ZIKV NS1 in com-plex withfive human antibodies at 2.6–2.9Åresolution.Group I antibodies(3G2 and 4B8)recognize the previously un-reported epitopes on the outer surface of the NS1 dimer.The unique binding mode of Group I antibodies led to a stronger recognition of the cell surface form of NS1 and completely inhibited secreted form non-structural protein 1(sNS1)-induced endothelial permeability via their immunoglobulin G(IgG)and Fab.Group II antibodies(4F10,2E11,and 14G5)recognize common epitopes in the distal end of the b-ladder domain,with a blockade efficiency that may be related to their affinity for the sNS1 protein and the presence of full-length IgG.Thesefindings elucidate the correlation between epitope recognition and protective efficacy of anti-NS1 antibodies and highlight the diagnostic and therapeutic potential of 3G2 and 4B8.

Zika virus non-structural protein 4B interacts with DHCR7 to facilitate viral infection

Zika virus(ZIKV)evolves non-structural proteins to evade immune response and ensure efficient replication in the host cells.Cholesterol metabolic enzyme 7-dehydrocholesterol reductase(DHCR7)was recently reported to impact innate immune responses in ZIKV infection.However,the vital non-structural protein and mechanisms involved in DHCR7-mediated viral evasion are not well elucidated.In this study,we demonstrated that ZIKV infection facilitated DHCR7 expression.Notably,the upregulated DHCR7 in turn facilitated ZIKV infection and blocking DHCR7 suppressed ZIKV infection.Mechanically,ZIKV non-structural protein 4B(NS4B)interacted with DHCR7 to induce DHCR7 expression.Moreover,DHCR7 inhibited TANK-binding kinase 1(TBK1)and interferon regulatory factor 3(IRF3)phosphorylation,which resulted in the reduction of interferon-beta(IFN-β)and interferon-stimulated genes(ISGs)productions.Therefore,we propose that ZIKV NS4B binds to DHCR7 to repress TBK1 and IRF3 activation,which in turn inhibits IFN-βand ISGs,and thereby facilitating ZIKV evasion.This study broadens the insights on how viral non-structural proteins antagonize innate immunity to facilitate viral infection via cholesterol metabolic enzymes and intermediates.

A multiple-target mRNA-LNP vaccine induces protective immunity against experimental multi-serotype DENV in mice

Dengue virus(DENV)is a mosquito-borne virus with a rapid spread to humans,causing mild to potentially fatal illness in hundreds of millions of people each year.Due to the large number of serotypes of the virus,there remains an unmet need to develop protective vaccines for a broad spectrum of the virus.Here,we constructed a modified mRNA vaccine containing envelope domain III(E-DIII)and non-structural protein 1(NS1)coated with lipid nanoparticles.This multi-target vaccine induced a robust antiviral immune response and increased neutralizing antibody titers that blocked all four types of DENV infection in vitro without significant antibodydependent enhancement(ADE).In addition,there was more bias for Th1 than Th2 in the exact E-DIII and NS1-specific T cell responses after a single injection.Importantly,intramuscular immunization limited DENV transmission in vivo and eliminated vascular leakage.Our findings highlight that chimeric allogeneic structural and non-structural proteins can be effective targets for DENV vaccine and that they can prevent the further development of congenital DENV syndrome.