In early infection, approximately 10% of nonstruc-tural protein nsP2 of Sindbis virus was transported into the nuclei of virus-infected BHK-21 cells. Nuclear nsP2 was dominantly associated with nuclear matrix. During ...In early infection, approximately 10% of nonstruc-tural protein nsP2 of Sindbis virus was transported into the nuclei of virus-infected BHK-21 cells. Nuclear nsP2 was dominantly associated with nuclear matrix. During the course of infection, increasing amounts of nsP2 accumulated in the nuclear fraction. A prominent accumulation of nuclear nsP2 occurred early in infection, from 1 h to 3 h postinfection. Meanwhile, a weak NTPase activity was found to be associated with the immunocomplexed nsP2. Nuclear localization of nsP2 and its possible role were discussed in relation to the inhibition of host macro-molecular synthesis.展开更多
[Objective]The study aimed to investigate the effects of Nsp2 protein on porcine reproductive and respiratory syndrome virus （ PRRSV） replication. [Method]Through in vitro cloning,the Nsp2 gene of highly pathogenic ...[Objective]The study aimed to investigate the effects of Nsp2 protein on porcine reproductive and respiratory syndrome virus （ PRRSV） replication. [Method]Through in vitro cloning,the Nsp2 gene of highly pathogenic PRRSV TJ and attenuated TJM were amplified by RT-PCR and cloned into the plasmid pEGFP-N1,which containing enhanced green fluorescent protein expression box. The constructed plasmids pEGFP-TJ Nsp2 and pEGFP-TJM Nsp2 were transfected into Marc-145 cells and screened by G418. Anti-G418 Marc-145-TJ Nsp2 and Marc-145-TJM Nsp2 cells were obtained,and the expression of Nsp2 protein in anti-G418 Marc-145-TJ Nsp2 and Marc-145-TJM Nsp2 cells was proved by PCR and RT- PCR. The Marc-145-TJ Nsp2 and Marc-145-TJM Nsp2 cells were infected by PRRSV,and TCID 50 was determined. [Result]The cells expressing Nsp2 gene of highly pathogenic PRRSV TJ and attenuated TJM,Marc-145-TJ Nsp2 and Marc-145-TJM Nsp2,were stable. PRRSV replication was fast in early stage on these cells. That is to say,Nsp2 protein played a positive role in early phase of PRRSV proliferation,and the effect of Nsp2 protein of highly pathogenic PRRSV TJ was more obvious. [Conclusion]The construction of Marc-145-Nsp2 cell lines provided data for the further discuss of PRRSV replication mechanism.展开更多
In the present study, 89 porcine reproductive and respiratory syndrome virus(PRRSV) isolates in China during 2007 to 2012 were randomly selected from the GenBank genetic sequence database. Evolutionary characteristics...In the present study, 89 porcine reproductive and respiratory syndrome virus(PRRSV) isolates in China during 2007 to 2012 were randomly selected from the GenBank genetic sequence database. Evolutionary characteristics of these isolates were analyzed based on the sequences of non-struc-tural protein 2(Nsp2) and glycoprotein 5(GP5). The genetic variations of the isolates were also compared with six representative strains. The results showed that a high degree of genetic diversity exists among the PRRSV population in China. Highly pathogenic PRRSV isolates, with a discon-tinuous deletion of a 30 amino acid residue in the Nsp2 region, remained the most dominant virus throughout 2007–2012 in China. Owing to the extensive use of representative vaccine strains, natu-ral recombination events occurred between strains. Three isolates – HH08, DY, and YN-2011 – were more closely related to vaccine strains than the other isolates. Both YN-2011 and DY were the evolu-tionary products of recombination events between strains SP and CH-1R. The results of the present study provide useful information for the epidemiology of PRRSV as well as for vaccine development.展开更多
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 development of effective drug...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 development of effective drugs against the deadly disease.SARS-CoV-2 non-structural protein 14(NSP14)carrying RNA cap guanine N7-methyltransferase and 30-50 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(DG)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 wereà37.2711±3.2160,à30.1746±3.1914,à23.8953±4.4800,andà34.1350±4.3683 kcal/mol,respectively,while the calculated binding free energies wereà60.2757±4.7708,à30.9955±2.9975,à46.3099±3.5689,andà59.8104±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.展开更多
Porcine reproductive and respiratory syndrome virus(PRRSV)is characterized by its genetic variation and limited cross protection among heterologous strains.Even though several viral structural proteins have been regar...Porcine reproductive and respiratory syndrome virus(PRRSV)is characterized by its genetic variation and limited cross protection among heterologous strains.Even though several viral structural proteins have been regarded as inducers of neutralizing antibodies(NAs)against PRRSV,the mechanism underlying limited cross-neutralization among heterologous strains is still controversial.In the present study,examinations of NA cross reaction between a highly pathogenic PRRSV(HP-PRRSV)strain,JXwn06,and a low pathogenic PRRSV(LP-PRRSV)strain,HB-1/3.9,were conducted with viral neutralization assays in MARC-145 cells.None of the JXwn06-hyperimmuned pigs’sera could neutralize HB-1/3.9 in vitro and vice versa.To address the genetic variation between these two viruses that are associated with limited crossneutralization,chimeric viruses with coding regions swapped between these two strains were constructed.Viral neutralization assays indicated that variations in nonstructural protein 2(nsp2)and structural proteins together contribute to weak cross-neutralization activity between JXwn06 and HB-1/3.9.Furthermore,we substituted the nsp2-,glycoprotein2(GP2)-,GP3-,and GP4-coding regions together,or nsp2-,GP5-,and membrane(M)protein-coding regions simultaneously between these two viruses to construct chimeric viruses to test cross-neutralization reactivity with hyperimmunized sera induced by their parental viruses.The results indicated that the swapped nsp2 and GP5-M viruses increased the neutralization reactivity with the donor strain antisera in MARC-145 cells.Taken together,these results show that variations in nsp2 and GP5-M correlate with the limited neutralization reactivity between the heterologous strains HP-PRRSV JXwn06 and LP-PRRSV HB-1/3.9.展开更多
AIM： To investigate effects of iron on oxidative stress, heme oxygenase-1 （HMOX1） and hepatitis C viral （HCV） expression in human hepatoma ceils stably expressing HCV proteins. METHODS： Effects of iron on oxidat...AIM： To investigate effects of iron on oxidative stress, heme oxygenase-1 （HMOX1） and hepatitis C viral （HCV） expression in human hepatoma ceils stably expressing HCV proteins. METHODS： Effects of iron on oxidative stress, HMOX1, and HCV expression were assessed in CON1 cells. Measurements included mRNA by quantitative reverse transcription-polymerase chain reaction, and protein levels by Western blots. RESULTS： Iron, in the form of ferric nitrilotriacetate,increased oxidative stress and upegulated HMOX1 gene expression. Iron did not affect mRNA or protein levels of Bach1, a repressor of HMOXl. Silencing the up-regulation of HMOXl nuclear factor-erythroid 2-related factor 2 （Nrf2） by Nrf2-siRNA decreased FeNTA-mediated up-regulation of HMOXl mRNA levels. These iron effects were completely blocked by deferoxamine （DFO）. Iron also significantly decreased levels of HCV core mRNA and protein by 80%-90%, nonstructural 5A mRNA by 90% and protein by about 50% in the Con1 full length HCV replicon cells, whereas DFO increased them. CONCLUSION： Excess iron up-regulates HMOXl and down-regulates HCV gene expression in hepatoma cells. This probably mitigates liver injury caused by combined iron overload and HCV infection.展开更多
Ca2+ plays a pivotal role in the physiology and biochemistry of prokaryotic and mammalian organisms.Viruses also utilize the universal Ca2+ signal to create a specific cellular environment to achieve coexistence with ...Ca2+ plays a pivotal role in the physiology and biochemistry of prokaryotic and mammalian organisms.Viruses also utilize the universal Ca2+ signal to create a specific cellular environment to achieve coexistence with the host,and to propagate.In this paper we first describe our development of a grafting approach to understand site-specific Ca2+ binding properties of EF-hand proteins with a helix-loop-helix Ca2+ binding motif,then summarize our prediction and identification of EF-hand Ca2+ binding sites on a genome-wide scale in bacteria and virus,and next report the application of the grafting approach to probe the metal binding capability of predicted EF-hand motifs within the streptococcal hemoprotein receptor(Shr) of Streptococcus pyrogenes and the nonstructural protein 1(nsP1) of Sindbis virus.When methods such as the grafting approach are developed in conjunction with prediction algorithms we are better able to probe continuous Ca2+-binding sites that have been previously underrepresented due to the limitation of conventional methodology.展开更多
文摘In early infection, approximately 10% of nonstruc-tural protein nsP2 of Sindbis virus was transported into the nuclei of virus-infected BHK-21 cells. Nuclear nsP2 was dominantly associated with nuclear matrix. During the course of infection, increasing amounts of nsP2 accumulated in the nuclear fraction. A prominent accumulation of nuclear nsP2 occurred early in infection, from 1 h to 3 h postinfection. Meanwhile, a weak NTPase activity was found to be associated with the immunocomplexed nsP2. Nuclear localization of nsP2 and its possible role were discussed in relation to the inhibition of host macro-molecular synthesis.
基金funded by the State " 863" Project of China(2011AA10A213)National Key Technology R & D Program in the 11th Five Year Plan of China (2009BADB4B02)
文摘[Objective]The study aimed to investigate the effects of Nsp2 protein on porcine reproductive and respiratory syndrome virus （ PRRSV） replication. [Method]Through in vitro cloning,the Nsp2 gene of highly pathogenic PRRSV TJ and attenuated TJM were amplified by RT-PCR and cloned into the plasmid pEGFP-N1,which containing enhanced green fluorescent protein expression box. The constructed plasmids pEGFP-TJ Nsp2 and pEGFP-TJM Nsp2 were transfected into Marc-145 cells and screened by G418. Anti-G418 Marc-145-TJ Nsp2 and Marc-145-TJM Nsp2 cells were obtained,and the expression of Nsp2 protein in anti-G418 Marc-145-TJ Nsp2 and Marc-145-TJM Nsp2 cells was proved by PCR and RT- PCR. The Marc-145-TJ Nsp2 and Marc-145-TJM Nsp2 cells were infected by PRRSV,and TCID 50 was determined. [Result]The cells expressing Nsp2 gene of highly pathogenic PRRSV TJ and attenuated TJM,Marc-145-TJ Nsp2 and Marc-145-TJM Nsp2,were stable. PRRSV replication was fast in early stage on these cells. That is to say,Nsp2 protein played a positive role in early phase of PRRSV proliferation,and the effect of Nsp2 protein of highly pathogenic PRRSV TJ was more obvious. [Conclusion]The construction of Marc-145-Nsp2 cell lines provided data for the further discuss of PRRSV replication mechanism.
基金supported by the Jilin Province Science and Technology Development Project(No.20140101123JC)the Fundamental Research Fund of Jilin Universitythe Program for Changjiang Scholars and Innovative Research Team in University(No.IRT1248)
文摘In the present study, 89 porcine reproductive and respiratory syndrome virus(PRRSV) isolates in China during 2007 to 2012 were randomly selected from the GenBank genetic sequence database. Evolutionary characteristics of these isolates were analyzed based on the sequences of non-struc-tural protein 2(Nsp2) and glycoprotein 5(GP5). The genetic variations of the isolates were also compared with six representative strains. The results showed that a high degree of genetic diversity exists among the PRRSV population in China. Highly pathogenic PRRSV isolates, with a discon-tinuous deletion of a 30 amino acid residue in the Nsp2 region, remained the most dominant virus throughout 2007–2012 in China. Owing to the extensive use of representative vaccine strains, natu-ral recombination events occurred between strains. Three isolates – HH08, DY, and YN-2011 – were more closely related to vaccine strains than the other isolates. Both YN-2011 and DY were the evolu-tionary products of recombination events between strains SP and CH-1R. The results of the present study provide useful information for the epidemiology of PRRSV as well as for vaccine development.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.31870135,31600116)the“1000 Talent Plan”of Sichuan Province(No.980)。
文摘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 development of effective drugs against the deadly disease.SARS-CoV-2 non-structural protein 14(NSP14)carrying RNA cap guanine N7-methyltransferase and 30-50 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(DG)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 wereà37.2711±3.2160,à30.1746±3.1914,à23.8953±4.4800,andà34.1350±4.3683 kcal/mol,respectively,while the calculated binding free energies wereà60.2757±4.7708,à30.9955±2.9975,à46.3099±3.5689,andà59.8104±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.
基金supported by the Major Program of National Natural Science Foundation of China (31490603, 31572549)the National Key Technology R & D Program of China (2015BAD12B01-2)
文摘Porcine reproductive and respiratory syndrome virus(PRRSV)is characterized by its genetic variation and limited cross protection among heterologous strains.Even though several viral structural proteins have been regarded as inducers of neutralizing antibodies(NAs)against PRRSV,the mechanism underlying limited cross-neutralization among heterologous strains is still controversial.In the present study,examinations of NA cross reaction between a highly pathogenic PRRSV(HP-PRRSV)strain,JXwn06,and a low pathogenic PRRSV(LP-PRRSV)strain,HB-1/3.9,were conducted with viral neutralization assays in MARC-145 cells.None of the JXwn06-hyperimmuned pigs’sera could neutralize HB-1/3.9 in vitro and vice versa.To address the genetic variation between these two viruses that are associated with limited crossneutralization,chimeric viruses with coding regions swapped between these two strains were constructed.Viral neutralization assays indicated that variations in nonstructural protein 2(nsp2)and structural proteins together contribute to weak cross-neutralization activity between JXwn06 and HB-1/3.9.Furthermore,we substituted the nsp2-,glycoprotein2(GP2)-,GP3-,and GP4-coding regions together,or nsp2-,GP5-,and membrane(M)protein-coding regions simultaneously between these two viruses to construct chimeric viruses to test cross-neutralization reactivity with hyperimmunized sera induced by their parental viruses.The results indicated that the swapped nsp2 and GP5-M viruses increased the neutralization reactivity with the donor strain antisera in MARC-145 cells.Taken together,these results show that variations in nsp2 and GP5-M correlate with the limited neutralization reactivity between the heterologous strains HP-PRRSV JXwn06 and LP-PRRSV HB-1/3.9.
基金Supported by Grant(DK RO1 38825) and contracts(DK NO129236 and UO1 DK 06193)from the National Institutes of Health(NIDDK)
文摘AIM： To investigate effects of iron on oxidative stress, heme oxygenase-1 （HMOX1） and hepatitis C viral （HCV） expression in human hepatoma ceils stably expressing HCV proteins. METHODS： Effects of iron on oxidative stress, HMOX1, and HCV expression were assessed in CON1 cells. Measurements included mRNA by quantitative reverse transcription-polymerase chain reaction, and protein levels by Western blots. RESULTS： Iron, in the form of ferric nitrilotriacetate,increased oxidative stress and upegulated HMOX1 gene expression. Iron did not affect mRNA or protein levels of Bach1, a repressor of HMOXl. Silencing the up-regulation of HMOXl nuclear factor-erythroid 2-related factor 2 （Nrf2） by Nrf2-siRNA decreased FeNTA-mediated up-regulation of HMOXl mRNA levels. These iron effects were completely blocked by deferoxamine （DFO）. Iron also significantly decreased levels of HCV core mRNA and protein by 80%-90%, nonstructural 5A mRNA by 90% and protein by about 50% in the Con1 full length HCV replicon cells, whereas DFO increased them. CONCLUSION： Excess iron up-regulates HMOXl and down-regulates HCV gene expression in hepatoma cells. This probably mitigates liver injury caused by combined iron overload and HCV infection.
文摘Ca2+ plays a pivotal role in the physiology and biochemistry of prokaryotic and mammalian organisms.Viruses also utilize the universal Ca2+ signal to create a specific cellular environment to achieve coexistence with the host,and to propagate.In this paper we first describe our development of a grafting approach to understand site-specific Ca2+ binding properties of EF-hand proteins with a helix-loop-helix Ca2+ binding motif,then summarize our prediction and identification of EF-hand Ca2+ binding sites on a genome-wide scale in bacteria and virus,and next report the application of the grafting approach to probe the metal binding capability of predicted EF-hand motifs within the streptococcal hemoprotein receptor(Shr) of Streptococcus pyrogenes and the nonstructural protein 1(nsP1) of Sindbis virus.When methods such as the grafting approach are developed in conjunction with prediction algorithms we are better able to probe continuous Ca2+-binding sites that have been previously underrepresented due to the limitation of conventional methodology.
