Nucleoprotein-based indirect enzyme-linked immunosorbent assay(indirect ELISA) for detecting antibodies specific to Ebola virus and Marbug virus

Full-length nucleoproteins from Ebola and Marburg viruses were expressed as His-tagged recombinant proteins in Escherichia coli and nucleoprotein-based enzyme-linked immunosorbent assays(ELISAs) were established for the detection of antibodies specific to Ebola and Marburg viruses. The ELISAs were evaluated by testing antisera collected from rabbit immunized with Ebola and Marburg virus nucleoproteins. Although little cross-reactivity of antibodies was observed in antiEbola virus nucleoprotein rabbit antisera, the highest reactions to immunoglobulin G(Ig G) were uniformly detected against the nucleoprotein antigens of homologous viruses. We further evaluated the ELISA's ability to detect antibodies to Ebola and Marburg viruses using human sera samples collected from individuals passing through the Guangdong port of entry. With a threshold set at the mean plus three standard deviations of average optical densities of sera tested, the ELISA systems using these two recombinant nucleoproteins have good sensitivity and specificity. These results demonstrate the usefulness of ELISA for diagnostics as well as ecological and serosurvey studies of Ebola and Marburg virus infection.

Expression of Nucleoprotein Gene of CTN Strain Rabies Virus from China in <i>E. coli </i>with Antigenicity

The nucleoprotein (NP) gene of rabies CTN strain isolated from China was recombined into pMal-c2x. The antigenicity of the recombined MBP-NP fusion proteins was examined by western blotting and by enzyme linked immunosorbent assay (ELISA). The results demonstrated that the recombined protein possesses predominant antigenicity.

Evaluation of Benzamide Derivatives as New Influenza A Nucleoprotein Inhibitors

Virus nucleoprotein (NP) is an emerging target for drug development for Influenza. We designed benzamide derivatives as new inhibitors of NP that demonstrate good potency in blocking influenza A. Screening revealed that compound 39 was the most potent molecule in the series, exhibiting IC50 values of 0.46 and 0.27 μM in blocking the replication of H3N2 (A/HK/8/68) and (A/WSN/33) influenza A viral strains. The observed inhibition of viral replication correlated well with cytopathic protection. Furthermore, based on computational analysis and fluorescence microscopy, it was determined that compound 39 inhibited nuclear accumulation by targeting influenza A viral nucleoproteins. Finally, the rodent pharmacokinetic profile of compound 32 displayed half-life of greater than 4 hours and bioavailability greater than 20%, suggesting this class of molecules had drug-like properties.

Phosphorylation sites within Ebola virus nucleoprotein

To understand the infection process, the viral multiplication and entry to the cell is widely studied. The Ebola virus nucleoprotein is the important problem for the pathological process. Focusing on the specific biological process, the post translational modification is needed. Here, the authors used the bioinformatics study to find the phosphorylation sites within the Ebola virus nucleoprotein and could identify many new sites.

Physiological Effects of Salmon Milt Nucleoprotein on Movement, Stress Tolerance and Lifespan of <i>C. elegans</i>

In recent years, various physiological functions of salmon milt extract, which consists of nucleic acid and nucleoprotein, have been reported. The objective of this study is to analyze the physiological function and its mechanism of salmon milt extract (NG) on nematodes (C. elegans). The wild type nematode N2 strain was bred on the plate containing of NG for four days, and its body length increased depending on NG concentration. When nematodes were bred with NG for a longer period, average lifespan was increased, and survival rate was increased by up to 20%. Generally, the movement of nematodes decreases with longer breeding period (i.e. aging). Analysis of movement (both gross thrashing movement and local pumping movement) showed that NG suppressed this decrease f movement with aging. Furthermore, the deease of survival rate by heat stress and oxidative stress was suppressed by NG administration. Nile Red staining analysis showed that fat accumulation varied depending on the concentration of NG. RT-PCR analysis revealed that the mRNA expression levels of the stress resistance genes sod-3 and sod-4 were increased. These results indicated that NG administration increased the expression of stress-tolerance-related genes, promoted stress tolerance, increased movement and prolonged lifespan in nematode.

SSINCC: Simple separation of interacting nucleoprotein complex components

Protein-DNA binding assays have been used in a va-riety of applications from fundamental studies re-garding the binding process itself to serve as probes for the detection, quantification and separation of target analytes. Here we describe a novel method of analyzing and identifying intermolecular DNA interactions that allows for the simple separation of interacting nucleoprotein complex components (SSINCC), focusing specifically on DNA-DNA interactions using P1 plasmid active partition system nucleoprotein complexes as a model to demonstrate DNA sequence specificity and tolerance of composite factor complexity. Traditional and recent assays of protein-DNA interaction are summarized and compared with SSINC. Although SSINC is examined here employing P1 partition nucleoprotein complex as an example of DNA-DNA intermolecular association, universal applications of this methodology to nucleo-protein complex studies can be envisioned.

Immunoglobulin G Specific Antibody Level against Ebola Viral Glycoprotein and Nucleoprotein in Ebola Virus Disease Survivors and Their Relatives

Ebola virus disease is a complex zoonosis that is highly virulent in humans. Despite its sorely pathogenic and lethal nature, survivors of this infection and even asymptomatic cases are able to develop both humoral and cellular immunity against several Ebola virus (EBOV) proteins. We aimed at determining immunoglobulin G (IgG) antibodies level against two Ebola viral antigens, the glycoprotein and the nucleoprotein in Ebola survivors and their relatives. Anti-EBOV glycoprotein (GP) and nucleoprotein (NP) IgG antibodies were quantified using ELISA. We enrolled 199 participants in two different sites as follow: 91 survivors at the Loreto clinic and 70 survivors with 38 relatives of Sierra Leone Association of Ebola Survivors Bombali Branch (SLAESB) tested for anti-EBOV NP and anti-EBOV GP IgG antibodies. Our findings revealed that the median anti-EBOV IgG level among survivors was 5.7128 U/ml [IQR: 2.793 - 7.783] for anti-EBOV GP IgG and 4.431 U/ml [IQR: 2.083 - 7.696] for anti-EBOV NP IgG. Survivors relatives had a median anti-EBOV GP IgG level of ?0.7128 U/ml [IQR: -0.903 to -0.04327] and -2.711 U/ml [IQR: -4.01 to -1.918] for anti-EBOV NP IgG. We observed that IgG levels in survivors were higher than in relatives with a significant difference of about 0.0001. The median value of anti-EBOV IgG level among seropositive relatives was 0.7043 U/ml [IQR: 0.5686 to 3.716] for anti-EBOV GP IgG and 4.05 U/ml [IQR: 0.2765 to 7.759] for anti-EBOV NP IgG respectively. Interestingly, we observed that 3.30% of Loreto clinic survivors did not developed anti-EBOV NP IgG antibodies;also about 10% survivors of the SLAESB were not reactive to anti-EBOV NP IgG and 1.43% of these survivors did not express antibodies against the Ebola viral glycoprotein. Our work is consistent with previous published studies showing heterogeneity in both survivors and asymptomatic cases of Ebola infection developing adaptive immunity against EBOV proteins.

CLINICAL SIGNIFICANCE OF DETECTING SERUM ANTIBODIES TO NUCLEOPROTEIN AND GLYCOPROTEIN G_2 OF HANTAAN VIRUS IN PATIENTS WITH HEMORRHAGIC FEVER WITH RENAL SYNDROME

Antibody blocking enzyme linked immunosorbent assays, respectively detecting antibodies to Hantaan virus nucleoprotein (NPAb) and glycoprotein GZ (G,Ab), were developed using monoclonal antibody L133, L13r3, LV48A and LVZB28B NPAb and GZAb in 291 serum samples from 65 patientswith kemorrkagic fever with renal syudrome (HFRS) were detfrmlned by these methods. The positive rates or NPAb were 90N on day 2-3 and 100 % on day 8-9 arter onset of disease, respectively.NPAb titers Increased during fever period and reached Peak levels during kypotensive and oliguric periods of HFRS. It was suggested that NPAb might be an important component Involved in the immunopathogenlc lin’alrmeut of HFRS and the detection of NPAb might be useful for the early diagnosis or HFRS. The I,osltlve rates and titers of GZAh were very low during the rirst three periods,namely rever, hypoteuslve and ollgurlc periods, and reached high levels during the convalescent period. GRAb titers were negatively related to the I,rotelnurla levels during the course of HFRS. It wasIndicated that GZAb might be the main component or neutralizing autlhodles to Hantaan virus Infection and the efrlclent production or GZAb was a good marker ror predicting the recovery and betterprognosis of HFRS.

Preparation and Initial Application of a Monoclonal Antibody Specific for a Newly Discovered Conserved Linear Epitope of Rabies Virus Nucleoprotein

Objective To prepare monoclonal antibodies against a newly discovered and conserved linear epitope of Rabies virus nucleoprotein and to use them in a rabies diagnostic test.Methods Synthetic peptide containing the epitope was used as immunogen to prepare hybridoma cell lines by classical hybridoma technology.Anti-peptide monoclonal antibodies produced in ascites of inoculated Balb/c mice were labeled with fluorescein isothiocyanate (FITC) after purification and used in fluorescent antibody test (FAT).Results Two positive hybridoma cell lines,RVNP-mAb1-CL and RVNP-mAb2-CL,were obtained.RVNP-mAb1-CL produced a higher concentration of monoclonal antibody RVNP-mAb1 in Balb/c ascites.FITC-labeled RVNP-mAb1 showed correct results on certain Rabies virus-positive canine brain tissue samples and cells of a small subclone of baby hamster kidney 21 cell line (BSR).Conclusion FITC-labeled RVNP-mAb1 has potential application for laboratory diagnosis of rabies.

Sequencing, Expression and Diagnostic Application of the Nucleoprotein Gene of Xinjiang Hemorrhagic Fever Virus

In order to analyze the nucleoprotein (NP) gene of Crimean-Congo hemorrhagic fever virus (CCHFV), viral RNA was amplified by RT-PCR by using the proof-reading DNA polymerase to produce the complete NP gene. The PCR product was sequenced, analyzed for phylogenesis and cloned into the expression vector pET32a and the recombinant plasmid expressed in E.coli BL-21 with high yield. The primarily purified fused protein was used to coat ELISA plates for the detect antibodies. It was found the similarities between NP gene of BA88166 and other XHFVs in nucleotide level and amino acid contents were very significant, and the NP gene of BA88166 encoded a nucleoprotein with 482 amino acid and a deduced molecular weight (MW) of 54?kDa. Western blot assay showed that the fusion protein expressed in bacteria possessed good antigenicity. The results with ELISA for the detection of the human and animal sera collected in endemic areas were found to be in good accordance to the clinical diagnosis. It concluded that the relations of NP genes of XHFV BA88166 and other XHFVs appeared to be evolutionally close. The methodologies established in this study were accurate, specific, rapid and reproducible for the clinical examinations and epidemiological survey.

Allopregnanolone targets nucleoprotein as a novel influenza virus inhibitor

Influenza A virus(IAV)poses a global public health concern and remains an imminent threat to human health.Emerging antiviral resistance to the currently approved influenza drugs emphasizes the urgent need for new therapeutic entities against IAV.Allopregnanolone(ALLO)is a natural product that has been approved as an antidepressant drug.In the present study,we repurposed ALLO as a novel inhibitor against IAVs.Mechanistic studies demonstrated that ALLO inhibited virus replication by interfering with the nucleus translocation of viral nucleoprotein(NP).In addition,ALLO showed significant synergistic activity with compound 16,a hemagglutinin inhibitor of IAVs.In summary,we have identified ALLO as a novel influenza virus inhibitor targeting NP,providing a promising candidate that deserves further investigation as a useful anti-influenza strategy in the future.

Structure and sequence analysis of influenza A virus nucleoprotein

Influenza A virus nucleoprotein (NP) forms homo-oligomers and multiple copies of NP wrap around genomic RNA, along with a trimeric polymerase making up ribonucleoprotein (RNP) complex. Sequence comparison of more than 2500 influenza A NP showed that this protein contains 30.1 % of polymorphic residues. NP is composed of a head and a body domain and a tail loop/ linker region. The head domain is more conserved than the body domain, as revealed from the structure-based sequence alignment. NP oligomerization is mediated by the insertion of the non-polymorphic and structurally conserved tail loop of one NP molecule to a groove of another NP. The different form of NP oligomers is due to the flexibility of the polymorphic linkers that join the tail loop to the rest of the protein. The RNA binding property of NP is known to involve the protruding element and the flexible basic loop between the head and body domains, both having high degree of primary sequence conservation. To bind RNA, NP may first capture the RNA by the flexible basic loop and then the RNA is clamped by the protruding element.

血清生长相关蛋白-43、α-突触核蛋白对小儿癫痫诊断价值研究

目的探讨癫痫患儿血清生长相关蛋白-43(GAP-43)、α-突触核蛋白(α-Syn)水平,分析两者对小儿癫痫的诊断价值。方法纳入2019年4月—2022年4月临汾市人民医院儿科诊治小儿癫痫患者80例为癫痫组,晕厥患儿50例为晕厥组,腹股沟斜疝患儿50例为对照组。利用酶联免疫吸附试验检测血清GAP-43、α-Syn水平;比较3组患儿间及不同临床特征癫痫患儿血清GAP-43、α-Syn水平差异;Pearson相关分析血清GAP-43、α-Syn与癫痫发作严重程度量表评分(NHS3)的相关性;受试者工作特征曲线分析血清GAP-43、α-Syn对小儿癫痫的诊断价值。结果血清GAP-43水平比较,癫痫组<晕厥组<对照组(F/P=821.793/<0.001),血清α-Syn水平比较,癫痫组>晕厥组>对照组(F/P=419.176/<0.001);癫痫患儿血清GAP-43在癫痫局灶性发作、无认知功能损害者中升高(t/P=8.745/<0.001,10.070/<0.001),α-Syn水平在癫痫局灶性发作、无认知功能损害者中降低(t/P=4.236/<0.001,14.881/<0.001),二者在患儿性别、年龄、脑电图异常、头颅MR异常者中比较,差异无统计学意义(P均>0.05);血清GAP-43水平与NHS3评分呈显著负相关(r/P=-0.645/<0.001),血清α-Syn水平与NHS3评分呈显著正相关(r/P=0.702/<0.001);血清GAP-43、α-Syn及两项联合预测小儿癫痫的AUC分别为0.740、0.738、0.835,二项联合的AUC高于单项预测(Z=4.482、4.391,P均<0.001)。结论癫痫患儿血清GAP-43降低,α-Syn水平升高,两者与癫痫类型、认知功能损害有关,两项联合对小儿癫痫具有较高的诊断价值。

血清CysC、α-Syn联合MRI对帕金森病病情评估及诊断的意义

目的 探讨血清胱抑素C(CysC)、α-突触核蛋白(α-Syn)联合磁共振成像(MRI)对帕金森病(PD)病情评估及诊断的意义。方法 将2019年4月至2021年4月于河北省沧州中西医结合医院(下称该院)治疗的PD患者87例纳入研究作为PD组。根据Hoehn-Yahr(H-Y)分期,将PD患者分为Ⅰ~Ⅱ期13例,Ⅲ~Ⅳ期45例,Ⅴ期29例。另外,选取同期于该院进行体检的健康志愿者87例作为对照组。比较各组血清CysC、α-Syn水平,分析血清CysC、α-Syn联合MRI对PD的诊断效能。结果 PD组血清CysC、α-Syn水平均高于对照组,差异有统计学意义(P<0.05);血清CysC、α-Syn水平随着H-Y分期递增升高(P<0.05)。PD组MRI各相位值与对照组比较,黑质致密带、苍白球、壳核、尾状核相位值均降低(P<0.05);不同H-Y分期的PD患者黑质致密带、苍白球、壳核相位值比较,差异均有统计学意义(P<0.05)。CysC、α-Syn单独诊断PD的AUC分别为0.786、0.767,灵敏度分别为58.62%、64.37%,特异度分别为88.51%、87.36%;与MRI、血清CysC、α-Syn单独诊断相比,三项联合诊断PD的灵敏度和准确度较高同,差异有统计学意义(P<0.05)。结论 血清CysC、α-Syn联合MRI对PD诊断效能较高,能为评估PD病情严重程度和早期诊断提供依据。

The nucleoprotein of severe fever with thrombocytopenia syndrome virus processes a stable hexameric ring to facilitate RNA encapsidation

Severe fever with thrombocytopenia syndrome virus(SFTSV),a member of the Phlebovirus genus from the Bunyaviridae family endemic to China,is the causative agent of life-threatening severe fever with thrombocyto-penia syndrome(SFTS),which features high fever and hemorrhage.Similar to other negative-sense RNA viruses,SFTSV encodes a nucleocapsid protein(NP)that is essen-tial for viral replication.NP facilitates viral RNA encapsida-tion and is responsible for the formation of ribonucleopro-tein complex.However,recent studies have indicated that NP from Phlebovirus members behaves in inhomogene-ous oligomerization states.In the present study,we report the crystal structure of SFTSV NP at 2.8Åresolution and demonstrate the mechanism by which it processes a ring-shaped hexameric form to accomplish RNA encapsida-tion.Key residues essential for oligomerization are identi-fi ed through mutational analysis and identifi ed to have a signifi cant impact on RNA binding,which suggests that correct formation of highly ordered oligomers is a criti-cal step in RNA encapsidation.The fi ndings of this work provide new insights into the discovery of new antiviral reagents for Phlebovirus infection.

Extracellular nucleoprotein exacerbates influenza viruspathogenesis by activating Toll-like receptor 4 and the NLRP3inflammasome

Host immune responses, such as those initiated by pattern recognition receptor (PRR) activation, are important for viralclearance and pathogenesis. However, little is known about the interactions of viral proteins with surface PRRs or, moreimportantly, the association of innate immune activation with viral pathogenesis. In this study, we showed that internalinfluenza virus proteins were released from infected cells. Among these proteins, nucleoprotein (NP) played a critical role inviral pathogenesis by stimulating neighboring cells through toll-like receptor (TLR)2, TLR4, and the NLR family pyrin domaincontaining 3 (NLRP3) inflammasome. Through the activation of these PRRs, NP induced the production of interleukin (IL)-1β andIL-6, which subsequently led to the induction of trypsin. Trypsin induced by NP increased the infectivity of influenza virus,leading to increases in viral replication and pathology upon subsequent viral infection. These results reveal the role of releasedNP in influenza pathogenesis and highlight the importance of the interactions of internal viral proteins with PRRs in theextracellular compartment during viral pathogenesis.

Nucleoprotein phosphorylation site(Y385)mutation confers temperature sensitivity to influenza A virus due to impaired nucleoprotein oligomerization at a lower temperature

Mutations in viral proteins can lead to the cold adaption of influenza A virus and the cold-adapted virus is an important vaccination instrument.Here,we identify a novel strain of influenza A virus with cold sensitivity conferred by a mutation at a phosphorylation site within the nucleoprotein(NP).The highly conserved tyrosine 385 residue(Y385)of NP was identified as a phosphorylation site by mass spectrometry.The constructive NP phosphorylation mimicked by Y385 E mutation was fatal for virus replication,while the continuous Y385 dephosphorylation mimicked by Y385 F mutation had little impact on virus replication in vitro.Notably,the Y385 F virus showed much lower replicative capacity in turbinates of mice compared with the wild type virus.Moreover,the replication of Y385 F virus was significantly reduced in both A549 and MDCK cells grown at 33℃,when compared to that at 37℃.These results indicated that the Y385 F mutation led to cold sensitivity of virus.We further found that the cold sensitivity of Y385 F virus could be attributed to diminished NP oligomerization rather than any changes in intracellular localization.Taken together,these findings suggest that the phosphorylation of NP may be a critical factor that regulates the temperature sensitivity of influenza A virus.

通用流感mRNA候选疫苗的构建及免疫效果评价

目的构建通用流感mRNA疫苗并全面评价其免疫保护效果。方法优化流感病毒株A/California/04/2009的血凝素(hemagglutinin,HA)、核蛋白(nucleoprotein,NP)和基质蛋白2胞外区(matrix protein 2 ectodomain,M2e)抗原序列,并将HA、NP和3个串联的M2e(3M2e)分别克隆至pcDNA3.1载体,通过线性化、体外转录、酶学法加帽、酶促加尾合成mRNA,命名为mRNA-HA、mRNA-NP和mRNA-3M2e。3种mRNA分别转染293T细胞后,通过免疫荧光实验鉴定蛋白的表达。利用脂质纳米颗粒分别包裹mRNA-HA、mRNA-NP和mRNA-3M2e并测量其粒径和电位。再将3种mRNA等体积混合制备成Comb-mRNA疫苗。将28只6周雌性Balb/c小鼠(体质量为18~22 g)按简单随机分组法分为2组:LNP组(n=14)和Comb-mRNA组(n=14)。通过血凝抑制(hemagglutination inhibition,HI)、微量中和(microneutralization,MN)实验评价流感mRNA疫苗诱导小鼠产生的血清抗体滴度;通过流式细胞术评价Comb-mRNA疫苗诱导的细胞免疫反应。采用5LD_(50)野生型H1N1流感病毒株感染小鼠评价Comb-mRNA疫苗的免疫保护效果。结果成功构建mRNA-HA、mRNA-NP和mRNA-3M2e,且3种mRNA均能在293T细胞表达。脂质纳米颗粒包裹mRNA平均粒径为(119.53±6.5)nm,平均电位为(-8.23±1.3)mV。与LNP组比较,Comb-mRNA组疫苗的HI几何平均滴度(geometric mean titer,GMT)达179.6,MN的GMT达201.6,同时诱导IFNγ+CD4+/CD8+T细胞比例升高。Comb-mRNA组在加强免疫后2周能够提供对5LD_(50)野生流感H1N1亚型病毒的保护。结论通用流感疫苗候选疫苗Comb-mRNA能够诱导小鼠免疫反应并保护小鼠免受病毒感染。

TP53INP1介导TGF-β1对膀胱癌细胞增殖、迁移的影响

目的 分析肿瘤蛋白53诱导的核蛋白1(TP53INP1)介导转化生长因子-β1(TGF-β1)对膀胱癌细胞增殖、迁移的影响。方法 选取2019年3月至2022年3月膀胱癌切除术的患者癌组织、癌旁组织标本40例,检测TP53INP1、TGF-β1表达量。膀胱癌细胞传代培养后分为TP53INP1-NC组、TP53INP1组、TGF-β1-NC组、TGF-β1组、TP53INP1+anti-TGF-β1-NC组、TP53INP1+anti-TGF-β1组。分析各组细胞增殖、凋亡、迁移情况。结果 与癌组织比较,癌旁组织TP53INP1、TGF-β1表达量较低(P<0.05)。与TP53INP1-NC组比较,TP53INP1组TP53INP1、B淋巴细胞瘤-2相关X蛋白(Bax)、天冬氨酸特异性半胱氨酸蛋白酶3(Caspase-3)、上皮性钙黏附素(E-cadherin)表达量、凋亡率水平较高,增殖率、细胞迁移数水平、B淋巴细胞瘤2基因(Bcl-2)、基质金属蛋白酶-2(MMP-2)、基质金属蛋白酶-9(MMP-9)表达量较低(P<0.05)。与TGF-β1-NC组比较,TGF-β1组TGF-β1、Bax、Caspase-3、E-cadherin表达量、凋亡率水平较高,增殖率、细胞迁移数水平、Bcl-2、MMP-2、MMP-9表达量较低(P<0.05)。双荧光素酶报告试验显示,与TGF-β1-NC组比较,TGF-β1组WT-TP53INP1荧光素酶活性降低(P<0.05),对MUT-TP53INP1荧光素酶活性影响较小(P>0.05)。与TP53INP1+anti-TGF-β1-NC组比较,TP53INP1+anti-TGF-β1组TGF-β1、Bax、Caspase-3、E-cadherin表达量、凋亡率水平较低(P<0.05),增殖率、细胞迁移数水平、Bcl-2、MMP-2、MMP-9表达量较高(P<0.05)。结论 TP53INP1可能通过靶向作用于TGF-β1而参与膀胱癌细胞增殖、凋亡、迁移,为膀胱癌诊治提供了新方向。

The two-stage interaction of Ebola virus VP40 with nucleoprotein results in a switch from viral RNA synthesis to virion assembly/ budding

Ebola virus(EBOV)is an enveloped negative-sense RNA virus and a member of the filovirus family.Nucleoprotein(NP)expression alone leads to the formation of inclusion bodies(IBs),which are critical for viral RNA synthesis.The matrix protein,VP40,not only plays a critical role in virus assembly/budding,but also can regulate transcription and replication of the viral genome.However,the molecular mechanism by which VP40 regulates viral RNA synthesis and virion assembly/budding is unknown.Here,we show that within IBs the N-terminus of NP recruits VP40 and is required for VLP-containing NP release.Furthermore,we find four point mutations(L692A,P697A,P698A and W699A)within the C-terminal hydrophobic core of NP result in a stronger VP40–NP interaction within IBs,sequestering VP40 within IBs,reducing VP40–VLP egress,abolishing the incorporation of NC-like structures into VP40–VLP,and inhibiting viral RNA synthesis,suggesting that the interaction of N-terminus of NP with VP40 induces a conformational change in the C-terminus of NP.Consequently,the C-terminal hydrophobic core of NP is exposed and binds VP40,thereby inhibiting RNA synthesis and initiating virion assembly/budding.