An etiogeno-pathological study on Kashin-Beck disease / 西安交通大学学报(医学版)

【Objective】 To find and identify the cause of Kashin-Beck disease (KBD). 【Methods】 We reviewed the bone slices of the KBD autopsy cases preserved in our institute, and observed the leukocyte lesions in peripheral blood smears of KBD children under a light microscope and ultrastructural lesions of leukocytes in KBD children under an electron microscope. We also observed the damages in cultured chondrocytes induced by plasma of children with KBD in an experiment. 【Results】 From the chondrocytes, bone marrow blood cells in KBD autopsy cases and leukocytes of KBD children, the entire pathological process in all the three type cells showed the same specific coagulation necrosis: the nucleus was enlarged; eosinophilic red inclusion bodies in varying sizes appeared in the nucleus, which were accompanied by dissolution and decrease of nuclear chromatin. If the lesion continued to deteriorate and progress, the entire nucleus would transform into a large red mass, and then subsequent series of changes of the inclusion bodies occurred; the cell body shrank and the cytoplasm was stained red. The cultured chondrocytes had replicated a cytopathic model equivalent to specific chondrocyte necrosis in the autopsy cases of KBD, and the viral nucleocapsids were detected in the nuclei of the cultured chondrocytes, with outcomes induced by plasma of the KBD children in the experiment. The same viral nucleocapsids as previously mentioned were also found in the nuclei of the white blood cells of the children with KBD. In the bone marrows of the autopsy cases, hyperemia, edema, fibrin exudation, focal necrosis of hematopoietic matrix and trabecular bone, and fibrosis all appeared. 【Conclusion】 The inclusion body formations were showed in the nuclei of necrotic chondrocytes, bone marrow blood cells of KBD autopsy cases, and in the nuclei of leukocytes in peripheral blood smears of KBD children. The inclusion body formation is the most well-known pathomorphological result of the viral cytocidal infection. Especially important is the positive results of cultured chondrocytes induced by plasma of KBD children in the experiment. What caused the necrosis of the three types of cells in KBD seems to be the twice-detected virus nucleocapsids, suggesting that this virus may have been the cause of KBD. There was an acute osteomyelitis with infectious delayed hypersensitivity in the bone marrows of the autopsy cases of KBD. KBD is a systemic infectious disease caused by the virus. All lesions in the cartilage, bone marrow, and blood are only parts of the systemic lesions.

Genotyping of nucleocapsid protein gene of HCV in HIVHCV co-infected patients in Kunming in 2019 / 中国热带医学

@#Abstract: Objective　To investigate the distribution characteristics of HCV genotypes and subtypes in patients with HIV (human immunodeficiency virus, HIV)/HCV co-infection in Kunming based on the nucleocapsid protein gene sequence of HCV (hepatitis C virus). Methods　Serum was collected from HIV/HCV co-infected patients with household registration in 14 county-level cities, districts and counties under the jurisdiction of Kunming, who admitted to Yunnan Provincial Infectious Disease Hospital from March to August 2019. The viral RNA was extracted from the serum, reverse transcribed to synthesize cDNA, and the HCV nucleocapsid protein gene-specific primers were used for nested PCR amplification. The positive amplification products were sequenced, bioinformatics software such as DNAstar and MEGAX were used for sequence analysis. Results　A total of 64 samples from co-infected patients with clinical diagnosis of suspected HIV/HCV were collected and amplified by HCV nucleocapsid protein gene-specific primers, of which 17 samples were amplified positively. The results of sequence analysis showed that the sequences of 9 cases were located in the same evolutionary branch as the HCV 3b subtype sequence, and the nucleotide homology was 93.3%-95.2%; the sequences of 5 cases were located in the same evolutionary branch as the HCV 1b subtype sequence, and the nucleotide homology was 96.8%-97.6%; the sequence of one case and the subtype sequence of HCV 3a gene were located in the same evolutionary branch, and the nucleotide homology was 95.2%; the sequence of one case and HCV 6n gene subtype sequence were located in the same evolutionary branch, and the nucleotide homology was 97.9%; One case was located in the same evolutionary branch as the HCV 6u gene subtype sequence, and the nucleotide homology was 98.4%. Conclusions　HCV 1b, HCV 3a, HCV 3b, HCV 6n and HCV 6u genotypes or subtypes of HCV are prevalent in Kunming, and HCV 3b is the most prevalent genotype.

A comparative study of antibody response, virus neutralization efficiency & metabolites in SARS-CoV-2-infected adults & children

Background & objectives: COVID-19 has been a global pandemic since early 2020. It has diverse clinical manifestations, but consistent immunological and metabolic correlates of disease severity and protection are not clear. This study was undertaken to compare seropositivity rate, antibody levels against nucleocapsid and spike proteins, virus neutralization and metabolites between adult and child COVID-19 patients. Methods: Plasma samples from naïve control (n=14) and reverse transcription (RT)-PCR positive COVID-19 participants (n=132) were tested for reactivity with nucleocapsid and spike proteins by ELISA, neutralization of SARS-CoV-2 infectivity in Vero cells and metabolites by 1H nuclear magnetic resonance (NMR) spectroscopy. Results: An ELISA platform was developed using nucleocapsid and spike proteins for COVID-19 serosurvey. The participants showed greater seropositivity for nucleocapsid (72%) than spike (55.3%), and males showed higher seropositivity than females for both the proteins. Antibody levels to both the proteins were higher in intensive care unit (ICU) than ward patients. Children showed lower seropositivity and antibody levels than adults. In contrast to ICU adults (81.3%), ICU children (33.3%) showed lower seropositivity for spike. Notably, the neutralization efficiency correlated with levels of anti-nucleocapsid antibodies. The levels of plasma metabolites were perturbed differentially in COVID-19 patients as compared with the naive controls. Interpretation & conclusions: Our results reflect the complexity of human immune response and metabolome to SARS-CoV-2 infection. While innate and cellular immune responses are likely to be a major determinant of disease severity and protection, antibodies to multiple viral proteins likely affect COVID-19 pathogenesis. In children, not adults, lower seropositivity rate for spike was associated with disease severity

Development of monoclonal antibody based IgG and IgM ELISA for diagnosis of severe fever with thrombocytopenia syndrome virus infection

ABSTRACT Introduction: Severe fever with thrombocytopenia syndrome virus (SFTSV) is a newly emerged virus that poses a great threat to human health because of high fatality rate. Methods: To develop sensitive and specific sero-diagnostic systems for SFTSV infections, monoclonal antibodies (MAbs) against recombinant SFTSV nucleocapsid (rSFTSV-N) protein were developed by immunizing BALB/C mice with rSFTSV-N protein and fusing the spleen cells with SP2/0 myeloma cells. Three hybridoma cell lines secreting MAbs against rSFTSV-N were obtained. MAb based IgG sandwich enzyme linked immunosorbent assay (ELISA) and IgM capture ELISA systems were established by using the newly developed MAbs. One hundred fifteen clinical suspected SFTS patients serum samples were used to evaluate the newly established systems by comparing with the total antibody detecting sandwich ELISA system and indirect ELISA systems. Results: The MAbs based sandwich IgG ELISA was perfectly matched with that of the total antibody sandwich ELISA and the indirect IgG ELISA. IgM capture ELISA results perfectly matched with that of the total antibody sandwich ELISA while detecting eight additional positive samples missed by the indirect IgM ELISA. Conclusions: The MAbs against rSFTSV-N protein offer new tools for SFTSV studies and our newly developed MAb-based IgG and IgM capture ELISA systems would offer safe and useful tools for diagnosis of SFTS virus infections and epidemiological investigations.

Desenvolvimento de teste diagnóstico não invasivo capaz de detectar anticorpos anti-SARS-CoV-2 em urina / Development of a non-invasive diagnostic test capable of detecting anti-SARS-CoV-2 antibodies in urine

A plataforma de ELISA (ensaio de imunoabsorção por ligação enzimática) tem sido amplamente utilizada para detectar anticorpos anti-SARS-CoV-2 gerados após a exposição ao vírus ou à vacinação. A amostra comumente utilizada para a realização do teste é o soro. Até o momento, nenhum estudo havia investigado a urina do paciente como amostra para detectar anticorpos específicos para o vírus SARS-CoV-2. A urina é um espécime biológico que traz vantagens significativas inerentes ao tipo de amostra, que compreende coleta não invasiva, de fácil manuseio e armazenamento. Neste trabalho, propomos um ELISA indireto in house baseado no uso de urina e proteínas recombinantes do Nucleocapsídeo (N) ou da Spike (S) do vírus SARS-CoV-2. As proteínas recombinantes (r) de SARS-CoV-2, N e as subunidades da proteína S (S-Glic, S1-NGlic e RBD-NGlic), foram avaliadas usando um painel composto por aproximadamente 200 amostras de urina e de soro. A presença de anticorpos anti-SARS-CoV-2 na urina foi detectada com sensibilidade e especificidade similares ou superiores ao soro, nas quais foram obtidos valores de sensibilidade de 94,0%, 75,0%, 81,38% e 89,66%, e especificidade de 100%, 96,0%, 96,77% e 96,77%, frente às proteínas rSARS-CoV-2 N, S-Glic, S1-NGlic e RBDNGlic, respectivamente. Dessa forma, os dados apresentados sugerem que a urina poderia ser considerada como uma potencial amostra biológica para aplicação em plataformas de imunodiagnóstico para a infecção por SARS-CoV-2, trazendo benefícios tanto no contexto individual quanto populacional.

The Enzyme-linked immunosorbent assay (ELISA) method has been widely used to detect anti-SARS-CoV-2 antibodies generated after exposure to the virus or vaccination. The sample usually used to perform the test is the serum. Thus far, no study has investigated the urine of patients as biological sample to detect specific SARS-CoV-2 antibodies. Urine is a biological specimen with significant advantages inherent to the type of sample, which comprises non-invasive collection, easy handling and storage. In this work, we propose an in house urine-based indirect ELISA using recombinant proteins from Nucleocapsid (N) and Spike (S) of the SARSCoV-2 virus. SARS-CoV-2 recombinant N and S protein subunits (Gly-S, NonGly-S1 and NonGly-RBD) were evaluated in an ELISA platform with a panel composed about 200 urine and serum samples. The presence of anti-SARS-CoV-2 antibodies in urine was detected with similar or superior sensitivity and specificity to serum, in which sensitivity values of 94.0%, 75.0%, 81.38% and 89.66% were obtained, while specificity values were of 100.0%, 96.0%, 96.77% and 96.77%, respectively, against rSARS-CoV-2 N, S-Glic, S1-NGlic and RBD-NGlic proteins. In conclusion, the data presented suggest that urine could be considered as a potential biological sample for application in immunodiagnostic platforms for SARS-CoV-2 infection, with benefits to the individual and population context.

The nucleocapsid protein of rice stripe virus in cell nuclei of vector insect regulates viral replication

Rice stripe virus (RSV) transmitted by the small brown planthopper causes severe rice yield losses in Asian countries. Although viral nuclear entry promotes viral replication in host cells, whether this phenomenon occurs in vector cells remains unknown. Therefore, in this study, we systematically evaluated the presence and roles of RSV in the nuclei of vector insect cells. We observed that the nucleocapsid protein (NP) and viral genomic RNAs were partially transported into vector cell nuclei by utilizing the importin α nuclear transport system. When blocking NP nuclear localization, cytoplasmic RSV accumulation significantly increased. In the vector cell nuclei, NP bound the transcription factor YY1 and affected its positive regulation to FAIM. Subsequently, decreased FAIM expression triggered an antiviral caspase-dependent apoptotic reaction. Our results reveal that viral nuclear entry induces completely different immune effects in vector and host cells, providing new insights into the balance between viral load and the immunity pressure in vector insects.

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.

Preparation of different fragments of SARS-CoV-2 N protein and its application in fluorescence chromatography / 生物工程学报

Different fragments of SARS-CoV-2 nucleocapsid (N) protein were expressed and purified, and a fluorescence immunochromatography method for detection of SARS-CoV-2 total antibody was established. The effect of different protein fragments on the performance of the method was evaluated. The N protein sequence was analyzed by bioinformatics technology, expressed in prokaryotic cell and purified by metal ion affinity chromatography column. Different N protein fragments were prepared for comparison. EDC reaction was used to label fluorescence microsphere on the synthesized antigen to construct sandwich fluorescence chromatography antibody detection assay, and the performance was systemically evaluated. Among the 4 prepared N protein fragments, the full-length N protein (N419) was selected as the optimized coating antigen, N412 with 0.5 mol/L NaCl was used as the optimal combination; deleting 91-120 amino acids from the N-terminal of N412 reduced non-specific signal by 87.5%. the linear range of detection was 0.312-80 U/L, the limit of detection was 0.165 U/L, and the accuracy was more than 95%. A fluorescence immunochromatographic detection method for analysis of SARS-CoV-2 total antibody was established by pairing N protein fragments. The detection result achieved 98% concordance with the commercially available Guangzhou Wanfu test strip, which is expected to be used as a supplementary approach for detection of SARS-CoV-2. The assay could also provide experimental reference for improving the performance of COVID-19 antibody detection reagents.

Prokaryotic expression, purification and antiserum preparation of severe acute respiratory syndrome coronavirus 2 nucleocapsid protein / 第二军医大学学报

Objective To express and purify the recombinant nucleocapsid (N) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and prepare antiserum from immunized mice. Methods The prokaryotic plasmid pET28a-N containing SARS-CoV-2 N gene was transformed into Escherichia coli BL21 (DE3). The expression of recombinant SARS-CoV-2 N protein was induced by isopropyl-β-D-thiogalactopyranoside. The Ni-NTA affinity chromatography column was used to purify the recombinant SARS-CoV-2 N protein, and antiserum was obtained from the BALB/c mice immunized with recombinant SARS-CoV-2 N protein combined with manganese adjuvant through intramuscular and subcutaneous injections. The reactions of recombinant SARS-CoV-2 N protein with SARS-CoV-2 N monoclonal antibodies and severe acute respiratory syndrome coronavirus (SARS-CoV) N polyclonal antibodies were detected by Western blotting. The reaction of mouse antiserum with the recombinant SARS-CoV-2 N protein expressed in the cells transfected with eukaryotic expression plasmid was examined by indirect immunofluorescence assay. Results The recombinant SARS-CoV-2 N protein was successfully induced and expressed as a soluble protein with a molecular weight of about 55 000. High concentration of purified protein was obtained. The results of Western blotting showed that the recombinant SARS-CoV-2 N protein could be specifically recognized by the SARS-CoV-2 N monoclonal antibodies and the SARS-CoV N polyclonal antibodies. The prepared mouse antiserum could also correctly recognize the recombinant SARS-CoV-2 N protein expressed in mammalian cells by indirect immunofluorescence assay. Conclusion Recombinant SARS-CoV-2 N protein has been successfully expressed and purified from the prokaryotic expression system, and mouse antiserum has been prepared, which lays a foundation for establishing a rapid SARS-CoV-2 diagnostic tool and further studying the function of SARS-CoV-2 N protein..

Crystal structure of SARS-CoV-2 nucleocapsid protein RNA binding domain reveals potential unique drug targeting sites

The outbreak of coronavirus disease (COVID-19) caused by SARS-CoV-2 virus continually lead to worldwide human infections and deaths. Currently, there is no specific viral protein-targeted therapeutics. Viral nucleocapsid protein is a potential antiviral drug target, serving multiple critical functions during the viral life cycle. However, the structural information of SARS-CoV-2 nucleocapsid protein remains unclear. Herein, we have determined the 2.7 Å crystal structure of the N-terminal RNA binding domain of SARS-CoV-2 nucleocapsid protein. Although the overall structure is similar as other reported coronavirus nucleocapsid protein N-terminal domain, the surface electrostatic potential characteristics between them are distinct. Further comparison with mild virus type HCoV-OC43 equivalent domain demonstrates a unique potential RNA binding pocket alongside the -sheet core. Complemented by binding studies, our data provide several atomic resolution features of SARS-CoV-2 nucleocapsid protein N-terminal domain, guiding the design of novel antiviral agents specific targeting to SARS-CoV-2.

Natural versus recombinant viral antigens in SARS-COV-2 serology: challenges in optimizing laboratory diagnosis of COVID19

OBJECTIVES: COVID-19 is a public health emergency of international concern whose detection in recovered asymptomatic patients is dependent on accurate diagnosis as it enables the estimation of the susceptibility of the population to the infection. This demand has resulted in the development of several commercial assays employing recombinant proteins, but the results of these assays are not reliable as they do not involve comparison with natural viral antigens. We independently used the SARS-CoV-2 whole viral antigen (WVA) and recombinant nucleocapsid protein (rNP) to develop in-house ELISAs for IgG detection; the results of these ELISAs were then compared to obtain reliable results. METHODS: WVA and rNP ELISAs were performed on COVID-19 negative sera from patients before the pandemic in Brazil, and on RT-qPCR-positive or SARS-CoV-2-IgG against rNP and IgG against WVA-positive samples from recently infected patients in Sao Paulo, Brazil. RESULTS: Both ELISAs detected a large fraction of infected patients but exhibited certain drawbacks. Higher signals and lower numbers of false-negatives were observed in rNP ELISA; however, a higher fraction of false-positives was observed in control groups. A high number of false-negatives was observed with WVA ELISA. Correlating the results of rNP and WVA ELISAs resulted in improved performance for COVID-19 diagnosis. CONCLUSION: The choice of antigen is an important aspect in optimizing the laboratory diagnosis of COVID-19. The use of rNP ELISA for the detection of anti-SARS-CoV-2 IgG antibodies seems promising, but comparison of the results with those of WVA ELISA is crucial for accurate test development prior to commercialization. IgG serology using several assays, and with the spectral patterns of SARS-CoV-2, resulted in confusing information that must be clarified before the establishment of diagnostic serology criteria.

Construction and characterization of a recombinant vaccine encoding the nucleocapsid protein gene of avian infectious bronchitis virus / Construção e caracterização de uma vacina recombinante codificando o gene da proteina do nucleocapsideo do virus da bronquite infecciosa das galinhas

A vacinação é a forma mais utilizada para prevenir a bronquite infecciosa causada pelo vírus da bronquite infecciosa das galinhas (IBV). Contudo, as vacinas convencionais são incapazes de diferenciar aves infectadas de vacinadas. No presente trabalho foi construído, caracterizado, e avaliado como candidato vacinal, um adenovírus recombinante expressando o gene N do IBV. O gene N foi clonado em um adenovírus humano tipo 5 defectivo e transfectado para as células HEK-293A para gerar rAd5_N. Após o vetor ser obtido como esperado e a confirmação da expressão da proteína N em HEK-293ª, foi realizada inoculação pela via oculo-nasal na dose de 10 7 TCID 50 /0,1mL para imunização de galinhas livres de patógenos específicos (SPF). A resposta imunológica do Ad5_N e a proteção contra o desafio ao IBV foram avaliadas e comparadas com uma vacina viva comercial. Não foram detectados anticorpos anti-IBV em aves vacinadas com o Ad5_N. A vacina comercial induziu anticorpos detectáveis a partir do 7º dia pós-vacinal. Em aves vacinadas com o Ad5_N não houve aumento na expressão de IFNγ. Neste estudo, o rAd5_N obtido não conferiu proteção contra desafio com IBV-M41. Os resultados indicam a necessidade de avaliar adenovírus recombinantes expressando outros genes do IBV.(AU)

Antigenic and immunogenic properties of the canine distemper virus nucleocapsid protein expressed in Escherichia coli employing codon optimized synthetic gene / Propriedades antigênicas e imunogênicas da proteína do nucleocapsídeo do virus da cinomose canina expressa em Escherichia coli empregando gene sintético com codons otimizados

Despite common occurrence and importance of canine distemper disease the majority of tests currently available for diagnosis are hampered by either low sensitivity or specificity. In this study it was evaluated antigenic and immunogenic characteristics of a conserved region of nucleocapsid protein of canine distemper virus (rCDV NP) expressed in Escherichia coli employing a codon optimized synthetic gene. The expression of rCDVNP in Star strain (mean 300μg/mL, purified) was confirmed by SDS-PAGE and Western blot analysis by using His-Tag monoclonal antibodies. Western blot and ELISA, employing positive and negative control dog sera, demonstrated the rCDVNP antigenicity. The rCDVNP was inoculated in hens and immunoglobulin Y (IgY) was purified from the egg yolk. The mean yield of IgY was 28.55mg/mL. IgY reacted with the recombinant protein as demonstrated by Western blot and ELISA assays. In summary, our findings demonstrated that rCDVNP is antigenic since CDV positive dog sera recognized the protein in vitro. Additionally, the rCDVNP proved to be immunogenic in hens being possible to isolate a high concentration of specific IgY antibodies from the egg yolk. Taken together, these results indicate that the rCDVNP along with the specific IgY could be useful tools for development of the canine distemper immunodiagnostic assays.(AU)

Apesar da ocorrência comum e importância da cinomose canina, a maioria dos testes atualmente disponíveis para diagnóstico são prejudicados pela baixa sensibilidade ou especificidade. Neste estudo foram avaliadas características antigênicas e imunogênicas de uma região conservada da proteína do nucleocapsídeo do virus da cinomose canina (rCDV NP) expressa em Escherichia coli empregando um gene sintético e codons otimizados. A expressão na cepa Star (média de 300μg/mL, purificada) foi confirmada por SDS-PAGE e Western blot utilizando anticorpos monoclonais anti-His-Tag. A antigenicidade da rCDVNP foi demonstrada por western blot e ELISA empregando soros de cães positivos e negativos. A rCDVNP foi inoculada em galinhas e imunoglobulina Y (gY) foi obtida e purificada a partir da gema. A produção média de IgY foi 28.55mg/mL. Anticorpos IgY reagiram com a proteína recombinante, quando analisados por Western blot e ELISA. Em resumo, nossos achados demonstram que a rCDVNP produzida é antigênica, uma vez que os anticorpos de soro de cães positivos para CDV reconheceram a proteína in vitro. Além disso, a rCDVNP foi imunogênica em galinhas, sendo possível isolar anticorpos IgY específicos a partir da gema do ovo em altas concentrações. Tomados em conjunto, estes resultados indicam que a rCDVNP juntamente com a IgY específica podem ser ferramentas úteis para elaborar ensaios de imunodiagnóstico de cinomose canina.(AU)

Nucleocapsid protein from porcine epidemic diarrhea virus isolates can antagonize interferon-λ production by blocking the nuclear factor-κB nuclear translocation / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Porcine epidemic diarrhea virus (PEDV) is a highly infectious pathogen that can cause severe diseases in pigs and result in enormous economic losses in the worldwide swine industry. Previous studies revealed that PEDV exhibits an obvious capacity for modulating interferon (IFN) signaling or expression. The newly discovered type III IFN, which plays a crucial role in antiviral immunity, has strong antiviral activity against PEDV proliferation in IPEC-J2 cells. In this study, we aimed to investigate the effect of PEDV nucleocapsid (N) protein on type III IFN-λ. We found that the N proteins of ten PEDV strains isolated between 2013 and 2017 from different local farms shared high nucleotide identities, while the N protein of the CV777 vaccine strain formed a monophyletic branch in the phylogenetic tree. The N protein of the epidemic strain could antagonize type III IFN, but not type I or type II IFN expression induced by polyinosinic-polycytidylic acid (poly(I:C)) in IPEC-J2 cells. Subsequently, we demonstrated that the inhibition of poly(I:C)-induced IFN-λ3 production by PEDV N protein was dependent on the blocking of nuclear factor-κB (NF-κB) nuclear translocation. These findings might help increase understanding of the pathogenesis of PEDV and its mechanisms for evading the host immune response.

Recombinant expression of hantaan virus protein N with application of Western-blot in detecting anti-hantavirus antibody / 中华流行病学杂志

Objective S gene of hantavirus(HV) was expressed in insect cells by genetic engineering technology.The expression product of S gene was used as antigen to detect anti-HV specific antibody IgG in serum.Methods Gene encoding NP of the strain HV-Z10 was amplified by PCR and then its eukaryotic expression system rBAC-Z 10S-TN was constructed by using the routine genetic engineering method.SDS-PAGE was applied to measure the expression of rNP.Ion-exchange plus Ni-NTA-affinity chromatography was performed to purify the recombinant product.Indirect immuno-fluorescence assay (IFA) was used to determine the specific immune-reactivity of rNP.WB assay was established to detect the serum samples from 95 confirmed HFRS patients.Parameters related to the outcomes of detection were compared with the routine HV-IgG IFA method.Results rBAC-Z10S-TN was able to express rNP with high efficiency.The purified rNP only showed a single protein fragment in the gel after SDS-PAGE.HV IgG could efficiently recognize rNP and hybridize with the recombinant protein.97.67％ of the serum samples from the HFRS patients were positive confirmed by WB.Conclusions We successfully constructed a high efficient prokaryotic expression system of NP encoding gene from hantavirus strain HV-Z10.WB assay which was established in this study could be used as a new serological test for HFRS diagnosis,thanks to the simplicity,safety,sensitivity and specificity of this method.

Recombinant expression of hantaan virus protein N with application of Western-blot in detecting anti-hantavirus antibody / 中华流行病学杂志

Objective S gene of hantavirus(HV) was expressed in insect cells by genetic engineering technology.The expression product of S gene was used as antigen to detect anti-HV specific antibody IgG in serum.Methods Gene encoding NP of the strain HV-Z10 was amplified by PCR and then its eukaryotic expression system rBAC-Z 10S-TN was constructed by using the routine genetic engineering method.SDS-PAGE was applied to measure the expression of rNP.Ion-exchange plus Ni-NTA-affinity chromatography was performed to purify the recombinant product.Indirect immuno-fluorescence assay (IFA) was used to determine the specific immune-reactivity of rNP.WB assay was established to detect the serum samples from 95 confirmed HFRS patients.Parameters related to the outcomes of detection were compared with the routine HV-IgG IFA method.Results rBAC-Z10S-TN was able to express rNP with high efficiency.The purified rNP only showed a single protein fragment in the gel after SDS-PAGE.HV IgG could efficiently recognize rNP and hybridize with the recombinant protein.97.67％ of the serum samples from the HFRS patients were positive confirmed by WB.Conclusions We successfully constructed a high efficient prokaryotic expression system of NP encoding gene from hantavirus strain HV-Z10.WB assay which was established in this study could be used as a new serological test for HFRS diagnosis,thanks to the simplicity,safety,sensitivity and specificity of this method.

Genetic diversity of nucleocapsid genes of recent porcine epidemic diarrhea viruses isolated in Korea

Porcine epidemic diarrhea virus (PEDV), a porcine enteropathogenic coronavirus, causes lethal watery diarrhea in piglets, resulting in large economic losses because of high mortality. In November 2013, PEDV reemerged in Korea, and these outbreaks have since continuously occurred. In the present study, we determined the full-length nucleocapsid (N) gene sequences of three Korean PEDV field isolates collected in 2014-2015. Sequence and phylogenetic analysis of N genes revealed that recent prevalent Korean PEDV isolates were very closely related to the US PEDV isolates in 2013. Interestingly, the phylogenetic tree based on the nucleotide sequencing of the PEDV N gene was similar to the tree topology of the PEDV complete genomes. Therefore, our data provide a better understanding of the genetic diversity and contribute to the accurate diagnosis and development of vaccines against PEDV.

Expression of SARS-CoV nucleocapsid protein in Bac-to-Bac Baculovirus System and antigenic analysis / 中国免疫学杂志

Objective:To express SARS-CoV nucleocapsid protein in Bac-to-Bac Baculovirus Expression System and analyze the antigenicity of the recombinant protein.Methods: The SARS-CoV nucleocapsid gene was amplified by PCR.The PCR product digested with BamHⅠand SalⅠrestriction endonucleases was cloned into vector pFastBac HTC of Bac-to-Bac Baculovirus expression system.Recombinant plasmid was transformed DH 10Bac cells to obtain the recombinant Bacmid DNA.Recombinant Bacmid DNA was transferred into Sf9 cells which were inducted to express the recombinant protein in High Five cells.After purified by Ni affinity chroma-tography ,the antigenicity of the recombinant protein was analyzed by Western blot and ELISA.Results:Recombinant plasmid was con-structed successfully.The recombinant protein with the relative molecular mass of 48 kD was efficiently expressed in High Five cells and purified successfully by Ni affinity chromatography.Western blot and ELISA analysis showed that the recombinant protein could be spe -cifically recognized by the monoclonal antibody to SARS-CoV N protein and immune serum from rabbits ,respectively.The recombinant protein can specifically reacted with serum from SARS patients ,not with serum from healthy persons and patients infected with hCoV-229 E and hCoV-OC43.Conclusion: SARS-CoV nucleocapsid protein has been expressed successfully in the Bac-to-Bac Baculovirus Expression System ,and obtained good antigenicity.It is preliminary deemed that it can't reacted with serum from patients infected with hCoV-229E and hCoV-OC43.

Production of CCHF Virus-Like Particle by a Baculovirus-Insect Cell Expression System / 中国病毒学·英文版

Crimean-Congo Haemorrhagic Fever Virus(CCHFV)is a tick-born virus of the Nairovirus genus within the Bunyaviridae family,which is widespread and causes,high fatality. The nucleocapsid of CCHFV is comprised of N proteins that are encoded by the S segment. In this research,the N protein of CCHFV was expressed in insect cells using a recombinant baculovirus. Under an electron microscope,Virus-Like Particles (VLPs)with various size and morphology were observed in cytoplasmic vesicles in the infected cells.Sucrose-gradient purification of the cell lysate indicated that the VLPs were mainly located in the upper fraction after ultracentrifugation,which was confirmed by Western blot analysis and immuno-electron microscopy(IEM).

The effect of nucleocapsid protein of severe acute respiratory syndrome-associated coronavirus on the expression of cyclooxygenase-2 / 中华传染病杂志

Objective To investigate the effect of nucleocapsid (N) protein of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) on the expression of cyclooxygenase-2 (COX-2). Methods 293T cells were co-transfected with reporter plasmid pCOX-2-Luc containing the luciferase gene under the control of COX-2 promoter and plasmids carrying individual genes of SARS-CoV, and luciferase activity was measured. Expression of COX-2 mRNA and protein was measured by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. Results N protein of SARS-CoV enhanced COX-2 gene promoter activity, and upregulated COX-2 mRNA expression.COX-2 protein production in 293T cells was N protein concentration-dependent. Conclusion N protein of SARS-CoV could specifically activate COX-2 expression.