Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus closely related to the human pathogens including yellow fever virus, dengue virus and West Nile virus. There are currently no effective antiviral therap...Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus closely related to the human pathogens including yellow fever virus, dengue virus and West Nile virus. There are currently no effective antiviral therapies for all of the flavivirus and only a few highly effective vaccines are licensed for human use. In this paper, the E protein domain III (DIII) of six heterologous flaviviruses (DENV1-4, WNV and JEV) was expressed in Escherichia coli successfully. The proteins were purified after a solubilization and refolding procedure, characterized by SDS-PAGE and Western blotting. Competitive inhibition showed that all recombinant flavivirus DIII proteins blocked the entry of JEV into BHK-21 cells. Further studies indicated that antibodies induced by the soluble recombinant flavivirus DIII partially protected mice against lethal JEV challenge. These results demonstrated that recombinant flavivirus DIII proteins could inhibit JEV infection competitively, and immunization with proper folding flavivirus DIII induced cross-protection against JEV infection in mice, implying a possible role of DIII for the cross-protection among flavivirus as well as its use in antigens for immunization in animal models.展开更多
AIM： To find a soluble and functional recombinant receptor-binding domain of severe acute respiratory syndrome-associated coronavirus （SARS-Cov）, and to analyze its receptor binding ability. METHODS： Three fusion ...AIM： To find a soluble and functional recombinant receptor-binding domain of severe acute respiratory syndrome-associated coronavirus （SARS-Cov）, and to analyze its receptor binding ability. METHODS： Three fusion tags （glutathione S-transferase, GST; thioredoxin, Trx; maltose-binding protein, MBP）, which preferably contributes to increasing solubility and to facilitating the proper folding of heteroprotein, were used to acquire the soluble and functional expression of RBD protein in Escherichia coli （BL21（DE3） and Rosetta-gamiB （DE3） strains）. The receptor binding ability of the purified soluble RBD protein was then detected by ELISA and flow cytometry assay. RESULTS： RBD of SARS-Cov spike protein was expressed as inclusion body when fused as TrxA tag form in both BL21 （DE3） and Rosetta-gamiB （DE3） under many different cultures and induction conditions. And there was no visible expression band on SDS-PAGE when RBD was expressed as MBP tagged form. Only GST tagged RBD was soluble expressed in BL21（DE3）, and the protein was purified by AKTA Prime Chromatography system. The ELISA data showed that GST.RBD antigen had positive reaction with anti-RBD mouse monoclonal antibody 1A5. Further flow cytometry assay demonstrated the high efficiency of RBD＇s binding ability to ACE2 （angiotensin-converting enzyme 2） positive Vero E6 cell. And ACE2 was proved as a cellular receptor that meditated an initial-affinity interaction with SARS-Cov spike protein. The geometrical mean of GST and GST.RBD binding to Vero E6 cells were 77.08 and 352.73 respectively. CONCLUSION： In this paper, we get sufficient soluble N terminal GST tagged RBD protein expressed in EcoliBL21 （DE3）; data from ELISA and flow cytometry assay demonstrate that the recombinant protein is functional and binding to ACE2 positive Vero E6 cell efficiently. And the recombinant RBD derived from E.coli can be used to developing subunit vaccine to block S protein binding with receptor and to neutralizing SARS-Cov infection.展开更多
E2 is an envelope glycoprotein of Classical swine fever virus (CSFV) and contains sequential neutralizing epitopes to induce virus-neutralizing antibodies and mount protective immunity in the natural host. In this stu...E2 is an envelope glycoprotein of Classical swine fever virus (CSFV) and contains sequential neutralizing epitopes to induce virus-neutralizing antibodies and mount protective immunity in the natural host. In this study, four antigen domains (ABCD) of the E2 gene was cloned from CSFV Shimen strain into the retroviral vector pBABE puro and expressed in eukaryotic cell (PK15) by an retroviral gene expression system, and the activity of recombinant E2 protein to induce immune responses was evaluated in rabbits. The results indicated that recombinant E2 protein can be recognized by fluorescence antibodies of CSFV and CSFV positive serum (Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China) using Western blot, indirect immunofluorescence antibody test (IFAT) and ELISA, Furthermore, anti-CSFV specific antibodies and lymphocyte proliferation were elicited and increased by recombinant protein after vaccination. In the challenge test, all of rabbits vaccinated with recombinant protein and Chinese vaccine strain (C-strain) were fully protected from a rabbit spleen virus challenge. These results indicated that a retroviral-based epitope-vaccine carrying the major antigen domains of E2 is able to induce high level of epitope-specific antibodies and exhibits similar protective capability with that induced by the C-strain, and encourages further work towards the development of a vaccine against CSFV infection.展开更多
Many studies point to an association between Helicobacter pylori(H.pylori)infection and inflammatory bowel diseases(IBD).Although controversial,this association indicates that the presence of the bacterium somehow aff...Many studies point to an association between Helicobacter pylori(H.pylori)infection and inflammatory bowel diseases(IBD).Although controversial,this association indicates that the presence of the bacterium somehow affects the course of IBD.It appears that H.pylori infection influences IBD through changes in the diversity of the gut microbiota,and hence in local chemical characteristics,and alteration in the pattern of gut immune response.The gut immune response appears to be modulated by H.pylori infection towards a less aggressive inflammatory response and the establishment of a targeted response to tissue repair.Therefore,a T helper 2(Th2)/macrophage M2 response is stimulated,while the Th1/macrophage M1 response is suppressed.The immunomodulation appears to be associated with intrinsic factors of the bacteria,such as virulence factors-such oncogenic protein cytotoxin-associated antigen A,proteins such H.pylori neutrophil-activating protein,but also with microenvironmental changes that favor permanence of H.pylori in the stomach.These changes include the increase of gastric mucosal pH by urease activity,and suppression of the stomach immune response promoted by evasion mechanisms of the bacterium.Furthermore,there is a causal relationship between H.pylori infection and components of the innate immunity such as the NLR family pyrin domain containing 3 inflammasome that directs IBD toward a better prognosis.展开更多
Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibi...Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibitory environment for axonal regeneration. Among these inhibitory molecules, myelinassociated inhibitors, including neurite outgrowth inhibitor A, oligodendrocyte myelin glycoprotein, myelin-associated glycoprotein, chondroitin sulfate proteoglycans and repulsive guidance molecule A are of particular importance. Due to their inhibitory nature, they represent exciting molecular targets to study axonal inhibition and regeneration after central injuries. These molecules are mainly produced by neurons, oligodendrocytes, and astrocytes within the scar and in its immediate vicinity. They exert their effects by binding to specific receptors, localized in the membranes of neurons. Receptors for these inhibitory cues include Nogo receptor 1, leucine-rich repeat, and Ig domain containing 1 and p75 neurotrophin receptor/tumor necrosis factor receptor superfamily member 19(that form a receptor complex that binds all myelin-associated inhibitors), and also paired immunoglobulin-like receptor B. Chondroitin sulfate proteoglycans and repulsive guidance molecule A bind to Nogo receptor 1, Nogo receptor 3, receptor protein tyrosine phosphatase σ and leucocyte common antigen related phosphatase, and neogenin, respectively. Once activated, these receptors initiate downstream signaling pathways, the most common amongst them being the Rho A/ROCK signaling pathway. These signaling cascades result in actin depolymerization, neurite outgrowth inhibition, and failure to regenerate after spinal cord injury. Currently, there are no approved pharmacological treatments to overcome spinal cord injuries other than physical rehabilitation and management of the array of symptoms brought on by spinal cord injuries. However, several novel therapies aiming to modulate these inhibitory proteins and/or their receptors are under investigation in ongoing clinical trials. Investigation has also been demonstrating that combinatorial therapies of growth inhibitors with other therapies, such as growth factors or stem-cell therapies, produce stronger results and their potential application in the clinics opens new venues in spinal cord injury treatment.展开更多
BACKGROUND Hepatitis B surface antigen(HBsAg)loss,a functional cure in patients with chronic hepatitis B(CHB)undergoing antiviral therapy,might be an ideal endpoint of antiviral treatment in clinical practice.The fact...BACKGROUND Hepatitis B surface antigen(HBsAg)loss,a functional cure in patients with chronic hepatitis B(CHB)undergoing antiviral therapy,might be an ideal endpoint of antiviral treatment in clinical practice.The factors that contribute to the functional cure remain unclear,and the predictors of functional cure are worth exploring.The concentration and kinetics of soluble programmed death-1(sPD-1)in patients with CHB may play an important role in elucidating the immune response associated with functional cure after nucleos(t)ide analogs therapy.AIM To investigate the factors associated with HBsAg loss and explore the influence of sPD-1 Levels.METHODS This study analyzed the data and samples from patients with CHB who underwent antiviral treatment in a non-interventional observational study conducted at Peking University First Hospital in Beijing(between 2007 and 2019).All patients were followed up:Serum samples were collected every 3 mo during the first year of antiviral treatment and every 6 mo thereafter.Patients with positive hepatitis B e antigen levels at baseline and with available sequential samples who achieved HBsAg loss during antiviral treatment served as the case group.This case group(n=11)was further matched to 44 positive hepatitis B e anti patients without HBsAg loss as controls.The Spearman’s rank correlation test and receiver operating characteristic curves analysis were performed.RESULTS The sPD-1 Levels were higher in patients with HBsAg loss than in those without HBsAg loss from baseline to month 96,and the differences were significant between the groups at baseline(P=0.0136),months 6(P=0.0003),12(P<0.0001),24(P=0.0007),48(P<0.0001),and 96(P=0.0142).After 6 mo of antiviral treatment,the sPD-1 levels were positively correlated with alanine transaminase(ALT)levels(r=0.5103,P=0.0017),and the sPD-1 levels showed apparent correlation with ALT(r=0.6883,P=0.0192)and HBV DNA(r=0.5601,P=0.0703)levels in patients with HBsAg loss.After 12 mo of antiviral treatment,the sPD-1 levels also showed apparent correlation with ALT(r=0.8134,P=0.0042)and HBV DNA(r=0.6832,P=0.0205)levels in patients with HBsAg loss.The sPD-1 levels were negatively correlated with HBsAg levels in all patients after 12 mo of antiviral treatment,especially at 24(r=-0.356,P=0.0497)and 48(r=-0.4783,P=0.0037)mo.After 6 mo of antiviral treatment,the AUC of sPD-1 for HBsAg loss was 0.898(P=0.000),whereas that of HBsAg was 0.617(P=0.419).The cut-off value of sPD-1 was set at 2.34 log pg/mL;the sensitivity and specificity were 100%and 66.7%,respectively.CONCLUSION The sPD-1 levels at 6 mo can predict HBsAg loss after 144 mo of antiviral treatment.展开更多
基金supported by Important National Science & Technology Specific Projects (2012ZX10004403, 2012ZX10004219)National Natural Scientific Fund of China (81072675)
文摘Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus closely related to the human pathogens including yellow fever virus, dengue virus and West Nile virus. There are currently no effective antiviral therapies for all of the flavivirus and only a few highly effective vaccines are licensed for human use. In this paper, the E protein domain III (DIII) of six heterologous flaviviruses (DENV1-4, WNV and JEV) was expressed in Escherichia coli successfully. The proteins were purified after a solubilization and refolding procedure, characterized by SDS-PAGE and Western blotting. Competitive inhibition showed that all recombinant flavivirus DIII proteins blocked the entry of JEV into BHK-21 cells. Further studies indicated that antibodies induced by the soluble recombinant flavivirus DIII partially protected mice against lethal JEV challenge. These results demonstrated that recombinant flavivirus DIII proteins could inhibit JEV infection competitively, and immunization with proper folding flavivirus DIII induced cross-protection against JEV infection in mice, implying a possible role of DIII for the cross-protection among flavivirus as well as its use in antigens for immunization in animal models.
文摘AIM： To find a soluble and functional recombinant receptor-binding domain of severe acute respiratory syndrome-associated coronavirus （SARS-Cov）, and to analyze its receptor binding ability. METHODS： Three fusion tags （glutathione S-transferase, GST; thioredoxin, Trx; maltose-binding protein, MBP）, which preferably contributes to increasing solubility and to facilitating the proper folding of heteroprotein, were used to acquire the soluble and functional expression of RBD protein in Escherichia coli （BL21（DE3） and Rosetta-gamiB （DE3） strains）. The receptor binding ability of the purified soluble RBD protein was then detected by ELISA and flow cytometry assay. RESULTS： RBD of SARS-Cov spike protein was expressed as inclusion body when fused as TrxA tag form in both BL21 （DE3） and Rosetta-gamiB （DE3） under many different cultures and induction conditions. And there was no visible expression band on SDS-PAGE when RBD was expressed as MBP tagged form. Only GST tagged RBD was soluble expressed in BL21（DE3）, and the protein was purified by AKTA Prime Chromatography system. The ELISA data showed that GST.RBD antigen had positive reaction with anti-RBD mouse monoclonal antibody 1A5. Further flow cytometry assay demonstrated the high efficiency of RBD＇s binding ability to ACE2 （angiotensin-converting enzyme 2） positive Vero E6 cell. And ACE2 was proved as a cellular receptor that meditated an initial-affinity interaction with SARS-Cov spike protein. The geometrical mean of GST and GST.RBD binding to Vero E6 cells were 77.08 and 352.73 respectively. CONCLUSION： In this paper, we get sufficient soluble N terminal GST tagged RBD protein expressed in EcoliBL21 （DE3）; data from ELISA and flow cytometry assay demonstrate that the recombinant protein is functional and binding to ACE2 positive Vero E6 cell efficiently. And the recombinant RBD derived from E.coli can be used to developing subunit vaccine to block S protein binding with receptor and to neutralizing SARS-Cov infection.
基金The National "973" (2005CB523201)Key Technology R&D Programme (2006BAD06A03)
文摘E2 is an envelope glycoprotein of Classical swine fever virus (CSFV) and contains sequential neutralizing epitopes to induce virus-neutralizing antibodies and mount protective immunity in the natural host. In this study, four antigen domains (ABCD) of the E2 gene was cloned from CSFV Shimen strain into the retroviral vector pBABE puro and expressed in eukaryotic cell (PK15) by an retroviral gene expression system, and the activity of recombinant E2 protein to induce immune responses was evaluated in rabbits. The results indicated that recombinant E2 protein can be recognized by fluorescence antibodies of CSFV and CSFV positive serum (Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China) using Western blot, indirect immunofluorescence antibody test (IFAT) and ELISA, Furthermore, anti-CSFV specific antibodies and lymphocyte proliferation were elicited and increased by recombinant protein after vaccination. In the challenge test, all of rabbits vaccinated with recombinant protein and Chinese vaccine strain (C-strain) were fully protected from a rabbit spleen virus challenge. These results indicated that a retroviral-based epitope-vaccine carrying the major antigen domains of E2 is able to induce high level of epitope-specific antibodies and exhibits similar protective capability with that induced by the C-strain, and encourages further work towards the development of a vaccine against CSFV infection.
文摘Many studies point to an association between Helicobacter pylori(H.pylori)infection and inflammatory bowel diseases(IBD).Although controversial,this association indicates that the presence of the bacterium somehow affects the course of IBD.It appears that H.pylori infection influences IBD through changes in the diversity of the gut microbiota,and hence in local chemical characteristics,and alteration in the pattern of gut immune response.The gut immune response appears to be modulated by H.pylori infection towards a less aggressive inflammatory response and the establishment of a targeted response to tissue repair.Therefore,a T helper 2(Th2)/macrophage M2 response is stimulated,while the Th1/macrophage M1 response is suppressed.The immunomodulation appears to be associated with intrinsic factors of the bacteria,such as virulence factors-such oncogenic protein cytotoxin-associated antigen A,proteins such H.pylori neutrophil-activating protein,but also with microenvironmental changes that favor permanence of H.pylori in the stomach.These changes include the increase of gastric mucosal pH by urease activity,and suppression of the stomach immune response promoted by evasion mechanisms of the bacterium.Furthermore,there is a causal relationship between H.pylori infection and components of the innate immunity such as the NLR family pyrin domain containing 3 inflammasome that directs IBD toward a better prognosis.
基金a Ph D fellowship by FCT-Fundacao para a Ciência Tecnologia (SFRH/BD/135868/2018)(to SSC)。
文摘Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibitory environment for axonal regeneration. Among these inhibitory molecules, myelinassociated inhibitors, including neurite outgrowth inhibitor A, oligodendrocyte myelin glycoprotein, myelin-associated glycoprotein, chondroitin sulfate proteoglycans and repulsive guidance molecule A are of particular importance. Due to their inhibitory nature, they represent exciting molecular targets to study axonal inhibition and regeneration after central injuries. These molecules are mainly produced by neurons, oligodendrocytes, and astrocytes within the scar and in its immediate vicinity. They exert their effects by binding to specific receptors, localized in the membranes of neurons. Receptors for these inhibitory cues include Nogo receptor 1, leucine-rich repeat, and Ig domain containing 1 and p75 neurotrophin receptor/tumor necrosis factor receptor superfamily member 19(that form a receptor complex that binds all myelin-associated inhibitors), and also paired immunoglobulin-like receptor B. Chondroitin sulfate proteoglycans and repulsive guidance molecule A bind to Nogo receptor 1, Nogo receptor 3, receptor protein tyrosine phosphatase σ and leucocyte common antigen related phosphatase, and neogenin, respectively. Once activated, these receptors initiate downstream signaling pathways, the most common amongst them being the Rho A/ROCK signaling pathway. These signaling cascades result in actin depolymerization, neurite outgrowth inhibition, and failure to regenerate after spinal cord injury. Currently, there are no approved pharmacological treatments to overcome spinal cord injuries other than physical rehabilitation and management of the array of symptoms brought on by spinal cord injuries. However, several novel therapies aiming to modulate these inhibitory proteins and/or their receptors are under investigation in ongoing clinical trials. Investigation has also been demonstrating that combinatorial therapies of growth inhibitors with other therapies, such as growth factors or stem-cell therapies, produce stronger results and their potential application in the clinics opens new venues in spinal cord injury treatment.
基金Supported by The 13^(th)Five-Year Plan of Ministry of Science and Technology of the People’s Republic of China,No.2017ZX10302201-004-009,and No.2017ZX10203202-003Beijing Municipal Science and Technology Commission of Major Projects,No.D161100002716002,and No.D161100002716003.
文摘BACKGROUND Hepatitis B surface antigen(HBsAg)loss,a functional cure in patients with chronic hepatitis B(CHB)undergoing antiviral therapy,might be an ideal endpoint of antiviral treatment in clinical practice.The factors that contribute to the functional cure remain unclear,and the predictors of functional cure are worth exploring.The concentration and kinetics of soluble programmed death-1(sPD-1)in patients with CHB may play an important role in elucidating the immune response associated with functional cure after nucleos(t)ide analogs therapy.AIM To investigate the factors associated with HBsAg loss and explore the influence of sPD-1 Levels.METHODS This study analyzed the data and samples from patients with CHB who underwent antiviral treatment in a non-interventional observational study conducted at Peking University First Hospital in Beijing(between 2007 and 2019).All patients were followed up:Serum samples were collected every 3 mo during the first year of antiviral treatment and every 6 mo thereafter.Patients with positive hepatitis B e antigen levels at baseline and with available sequential samples who achieved HBsAg loss during antiviral treatment served as the case group.This case group(n=11)was further matched to 44 positive hepatitis B e anti patients without HBsAg loss as controls.The Spearman’s rank correlation test and receiver operating characteristic curves analysis were performed.RESULTS The sPD-1 Levels were higher in patients with HBsAg loss than in those without HBsAg loss from baseline to month 96,and the differences were significant between the groups at baseline(P=0.0136),months 6(P=0.0003),12(P<0.0001),24(P=0.0007),48(P<0.0001),and 96(P=0.0142).After 6 mo of antiviral treatment,the sPD-1 levels were positively correlated with alanine transaminase(ALT)levels(r=0.5103,P=0.0017),and the sPD-1 levels showed apparent correlation with ALT(r=0.6883,P=0.0192)and HBV DNA(r=0.5601,P=0.0703)levels in patients with HBsAg loss.After 12 mo of antiviral treatment,the sPD-1 levels also showed apparent correlation with ALT(r=0.8134,P=0.0042)and HBV DNA(r=0.6832,P=0.0205)levels in patients with HBsAg loss.The sPD-1 levels were negatively correlated with HBsAg levels in all patients after 12 mo of antiviral treatment,especially at 24(r=-0.356,P=0.0497)and 48(r=-0.4783,P=0.0037)mo.After 6 mo of antiviral treatment,the AUC of sPD-1 for HBsAg loss was 0.898(P=0.000),whereas that of HBsAg was 0.617(P=0.419).The cut-off value of sPD-1 was set at 2.34 log pg/mL;the sensitivity and specificity were 100%and 66.7%,respectively.CONCLUSION The sPD-1 levels at 6 mo can predict HBsAg loss after 144 mo of antiviral treatment.
