[Objectives]Laoshan black tea was subjected to supercritical CO_(2) extraction. [Methods]The extraction conditions of Laoshan black tea were studied by an orthogonal experiment and optimized by response surface method...[Objectives]Laoshan black tea was subjected to supercritical CO_(2) extraction. [Methods]The extraction conditions of Laoshan black tea were studied by an orthogonal experiment and optimized by response surface methodology. [Results] The optimum extraction conditions of black tea extract by supercritical CO_(2) extraction were as follows: extraction pressure 23.53 MPa, extraction time 1.73 h, and extraction temperature 49.75 ℃, with which the extract yield could reach 5.15% theoretically. [Conclusions] Based on the traditional extraction process, a supercritical extraction method optimized by response surface methodology and a unique extraction process were formed, which enriches the extraction processes and methods of natural raw materials.展开更多
African swine fever virus(ASFV)has been circulating in China for more than two years,and it is not clear whether the biological properties of the virus have changed.Here,we report on our surveillance of ASFVs in seven...African swine fever virus(ASFV)has been circulating in China for more than two years,and it is not clear whether the biological properties of the virus have changed.Here,we report on our surveillance of ASFVs in seven provinces of China,from June to December,2020.A total of 22 viruses were isolated and characterized as genotype II ASFVs,with mutations,deletions,insertions,or short-fragment replacement occurring in all isolates compared with Pig/HLJ/2018(HLJ/18),the earliest isolate in China.Eleven isolates had four different types of natural mutations or deletion in the EP402R gene and displayed a nonhemadsorbing(non-HAD)phenotype.Four isolates were tested for virulence in pigs;two were found to be as highly lethal as HLJ/18.However,two non-HAD isolates showed lower virulence but were highly transmissible;infection with 106 TCID50 dose was partially lethal and caused acute or sub-acute disease,whereas 103 TCID50 dose caused non-lethal,sub-acute or chronic disease,and persistent infection.The emergence of lower virulent natural mutants brings greater difficulty to the early diagnosis of ASF and creates new challenges for ASFV control.展开更多
Zika virus(ZIKV)is emerging as a significant pathogen worldwide and may cause severe neurological disorders such as fetal microcephaly and Guillain-Barre syndrome.No drug or listed vaccines are currently available for...Zika virus(ZIKV)is emerging as a significant pathogen worldwide and may cause severe neurological disorders such as fetal microcephaly and Guillain-Barre syndrome.No drug or listed vaccines are currently available for preventing ZIKV infection.As a major target of neutralizing,ZIKV envelop(E)protein usually used for vaccine development.Nevertheless,the immunogenicity of ZIKV envelop(E)protein expressed by baculovirus display system has never been assessed.In this study,we reported a new strategy for surface display of ZIKV E protein by a recombinant baculovirus vector derived from Autographa californica multiple nuclear polyhedrosis virus(AcMNPV)and assessed its immunogenicity in mice.We produced recombinant fusion ZIKV E protein linked with signal peptide(SP)and transmembrane domain(TM)of AcMNPV GP64.The results showed that the recombinant protein was easy to produce by baculovirus display system.BALB/c mice immunized with this recombinant E protein developed ZIKV specific serum antibodies.The anti-E protein sera from the mice were able to effectively neutralize ZIKV in vitro.More importantly,AG6(IFN-a/b and IFN-c receptor deficient)mice immunized with recombinant E protein were protected against lethal ZIKV challenge.Together,thesefindings demonstrated that the recombinant E protein displayed by baculovirus can be conveniently prepared and displayed good immunogenicity in immunized mice.It is a promising practical approach for prompting the development of vaccine and related immunology research.展开更多
Tick-borne encephalitis virus(TBEV) is a pathogenic virus known to cause central nervous system(CNS) diseases in humans, and has become an increasing public health threat nowadays. The rates of TBEV infection in the e...Tick-borne encephalitis virus(TBEV) is a pathogenic virus known to cause central nervous system(CNS) diseases in humans, and has become an increasing public health threat nowadays. The rates of TBEV infection in the endemic countries are increasing. However, there is no effective antiviral against the disease. This underscores the urgent need for tools to study the emergence and pathogenesis of TBEV and to accelerate the development of vaccines and antivirals. In this study, we reported an infectious c DNA clone of TBEV that was isolated in China(the WH2012 strain). A beta-globin intron was inserted in the coding region of nonstructural protein 1(NS1) gene to improve the stability of viral genome in bacteria. In mammalian cells, the inserted intron was excised and spliced precisely, which did not lead to the generation of inserted mutants. High titers of infectious progeny viruses were generated after the transfection of the infectious clone. The cDNA-derived TBEV replicated efficiently, and caused typical cytopathic effect(CPE) and plaques in BHK-21 cells. In addition, the CPE and growth curve of cDNA-derived virus were similar to that of its parental isolate in cells. Together, we have constructed the first infectious TBEV cDNA clone in China, and the clone can be used to investigate the genetic determinants of TBEV virulence and disease pathogenesis, and to develop countermeasures against the virus.展开更多
A submerged turbulent plane jet in shallow water impinging vertically onto the free surface will produce a large-scale flapping motion when the jet exit velocity is larger than a critical one.The flapping phenomenon i...A submerged turbulent plane jet in shallow water impinging vertically onto the free surface will produce a large-scale flapping motion when the jet exit velocity is larger than a critical one.The flapping phenomenon is verified in this paper through a large eddy simulation where the free surface is modeled by volume of fluid approach.The quantitative results for flapping jet are found to be in good agreement with available experimental data in terms of mean velocity,flapping-induced velocity and turbulence intensity.Results show that the flapping motion is a new flow pattern with characteristic flapping frequency for submerged turbulent plane jets,the mean centerline velocity decay is considerably faster than that of the stable impinging jet without flapping motion,and the flapping-induced velocities are as important as the turbulent fluctuations.展开更多
文摘[Objectives]Laoshan black tea was subjected to supercritical CO_(2) extraction. [Methods]The extraction conditions of Laoshan black tea were studied by an orthogonal experiment and optimized by response surface methodology. [Results] The optimum extraction conditions of black tea extract by supercritical CO_(2) extraction were as follows: extraction pressure 23.53 MPa, extraction time 1.73 h, and extraction temperature 49.75 ℃, with which the extract yield could reach 5.15% theoretically. [Conclusions] Based on the traditional extraction process, a supercritical extraction method optimized by response surface methodology and a unique extraction process were formed, which enriches the extraction processes and methods of natural raw materials.
基金the National Key Research and Development Program of China(2018YFC1200601)Applied Technology Research and Development Project of Heilongjiang Province(GA19B301)+2 种基金Key-Area Research and Development Program of Guangdong Province(2019B020211004)the State Key Laboratory of Veterinary Biotechnology Program(SKLVBP201801)the National Natural Science Foundation of China(31941002)。
文摘African swine fever virus(ASFV)has been circulating in China for more than two years,and it is not clear whether the biological properties of the virus have changed.Here,we report on our surveillance of ASFVs in seven provinces of China,from June to December,2020.A total of 22 viruses were isolated and characterized as genotype II ASFVs,with mutations,deletions,insertions,or short-fragment replacement occurring in all isolates compared with Pig/HLJ/2018(HLJ/18),the earliest isolate in China.Eleven isolates had four different types of natural mutations or deletion in the EP402R gene and displayed a nonhemadsorbing(non-HAD)phenotype.Four isolates were tested for virulence in pigs;two were found to be as highly lethal as HLJ/18.However,two non-HAD isolates showed lower virulence but were highly transmissible;infection with 106 TCID50 dose was partially lethal and caused acute or sub-acute disease,whereas 103 TCID50 dose caused non-lethal,sub-acute or chronic disease,and persistent infection.The emergence of lower virulent natural mutants brings greater difficulty to the early diagnosis of ASF and creates new challenges for ASFV control.
基金supported by grants from the National Key R&D Program of China(2016YFD0500406)the National Natural Science Foundation of China(NSFC)(no.81672036)the Youth Innovation Promotion Association of CAS(2016302)
文摘Zika virus(ZIKV)is emerging as a significant pathogen worldwide and may cause severe neurological disorders such as fetal microcephaly and Guillain-Barre syndrome.No drug or listed vaccines are currently available for preventing ZIKV infection.As a major target of neutralizing,ZIKV envelop(E)protein usually used for vaccine development.Nevertheless,the immunogenicity of ZIKV envelop(E)protein expressed by baculovirus display system has never been assessed.In this study,we reported a new strategy for surface display of ZIKV E protein by a recombinant baculovirus vector derived from Autographa californica multiple nuclear polyhedrosis virus(AcMNPV)and assessed its immunogenicity in mice.We produced recombinant fusion ZIKV E protein linked with signal peptide(SP)and transmembrane domain(TM)of AcMNPV GP64.The results showed that the recombinant protein was easy to produce by baculovirus display system.BALB/c mice immunized with this recombinant E protein developed ZIKV specific serum antibodies.The anti-E protein sera from the mice were able to effectively neutralize ZIKV in vitro.More importantly,AG6(IFN-a/b and IFN-c receptor deficient)mice immunized with recombinant E protein were protected against lethal ZIKV challenge.Together,thesefindings demonstrated that the recombinant E protein displayed by baculovirus can be conveniently prepared and displayed good immunogenicity in immunized mice.It is a promising practical approach for prompting the development of vaccine and related immunology research.
基金This study was supported by grants from the National Key R&D Program of China(2018YFA0507201)。
文摘Tick-borne encephalitis virus(TBEV) is a pathogenic virus known to cause central nervous system(CNS) diseases in humans, and has become an increasing public health threat nowadays. The rates of TBEV infection in the endemic countries are increasing. However, there is no effective antiviral against the disease. This underscores the urgent need for tools to study the emergence and pathogenesis of TBEV and to accelerate the development of vaccines and antivirals. In this study, we reported an infectious c DNA clone of TBEV that was isolated in China(the WH2012 strain). A beta-globin intron was inserted in the coding region of nonstructural protein 1(NS1) gene to improve the stability of viral genome in bacteria. In mammalian cells, the inserted intron was excised and spliced precisely, which did not lead to the generation of inserted mutants. High titers of infectious progeny viruses were generated after the transfection of the infectious clone. The cDNA-derived TBEV replicated efficiently, and caused typical cytopathic effect(CPE) and plaques in BHK-21 cells. In addition, the CPE and growth curve of cDNA-derived virus were similar to that of its parental isolate in cells. Together, we have constructed the first infectious TBEV cDNA clone in China, and the clone can be used to investigate the genetic determinants of TBEV virulence and disease pathogenesis, and to develop countermeasures against the virus.
基金The work was supported by National Natural Science Foundation of China(Grant No.10472046)the Priority Academic Program Development of Jiangsu Higher Education Institutions,grants from the Postgraduate Research and Innovation Project of Jiangsu Province(GrantNo.CX08B 035)PhD Thesis Innovation and Excellence Fund of NUAA(Grant No.BCXJ08-01).
文摘A submerged turbulent plane jet in shallow water impinging vertically onto the free surface will produce a large-scale flapping motion when the jet exit velocity is larger than a critical one.The flapping phenomenon is verified in this paper through a large eddy simulation where the free surface is modeled by volume of fluid approach.The quantitative results for flapping jet are found to be in good agreement with available experimental data in terms of mean velocity,flapping-induced velocity and turbulence intensity.Results show that the flapping motion is a new flow pattern with characteristic flapping frequency for submerged turbulent plane jets,the mean centerline velocity decay is considerably faster than that of the stable impinging jet without flapping motion,and the flapping-induced velocities are as important as the turbulent fluctuations.
