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Objective:To establish an antibody expression system to reduce the antibody-dependent enhancement (ADE) effect of target antibody.Methods:Site-directed mutagenesis was used to mutate the 234 and 235 sites of the Fc region of the mammalian cell antibody expression vector-L234A and L235A to establish the antibody expression vector pFRT-IgG1κ-FcM. An antibody Wt-WNV with significant ADE effect obtained in previous work was selected and expressed by the pFRT-IgG1κ-FcM system to obtain mutant antibody FcM-WNV. The binding ability of FcM-WNV to target antigen West Nile virus envelope protein-DⅢ (WNV E-DⅢ) was detected by ELISA, and the its binding ability to human high-affinity IgG Fc receptor hFcγRⅠ (hCD64 ) was analyzed by flow cytometry. The neutralizing activity of FcM-WNV in vitro was detected by pseudovirus infection of host cells (BHK21 and K562). Results:The expression levels of FcM-WNV and Wt-WNV were comparable, and FcM-WNV could recognize and bind to WNVE-DIII in a concentration-dependent manner. Compared with Wt-WNV, the binding ability of FcM-WNV to hCD64 was significantly weakened, showing a significant decrease in fluorescence intensity. Consistent with the previous experimental results, Wt-WNV at a concentration of 5 μg/ml significantly enhanced the infection of K562 by WNV pseudovirus, while FcM-WNV at a concentration of 5 μg/ml could effectively block pseudovirus infection in both K562 and BHK21 cells.Conclusions:The established antibody expression system can effectively reduce the ADE effect of the target antibody.
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Objective:To establish an in vivo infection model of H5N1 pseudovirus and to detect the neutralizing activity of FHA3 antibody using this model. Methods:Based on the sequence information of hemagglutinin (HA) and neuraminidase (NA) of A/Anhui/1/2005/H5N1 strain, two recombinant plasmids of pcDNA3.1-HA5 and pcDNA3.1-NA1 were constructed. The two plasmids and plasmid pNL4-3.Luc.R-E- were co-transfected into 293T cells to prepare H5N1 pseudovirus supernatant. The morphology of pseudovirus particles in the supernatant was observed by electron microscopy. MDCK cells were infected with the pseudovirus supernatant and the virus titer was detected. BALB/c mice were injected with the pseudovirus supernatant by intraperitoneal injection and subjected to bioluminescence imaging at 2, 5, 8, and 12 d after infection to detect the pseudovirus infection in vivo. The functional activity of FHA3 antibody in vivo was evaluated using the established mouse infection model. Results:The recombinant plasmids pcDNA3.1-HA5 and pcDNA3.1-NA1 were correctly constructed and could be used to prepare pseudovirus supernatants of high titer by co-transfecting 293T cells with the plasmid pNL4-3.Luc.R-E-. The virus particles were round under electron microscope. H5N1 pseudovirus-infected mice exhibits strong fluorescence signals, which were attenuated by FHA3 treatment before challenge.Conclusions:The in vivo infection model of H5N1 pseudovirus was successfully constructed and FHA3 antibody was proved to be protective against the pseudovirus infection.
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Objective:To prepare and identify a broad-spectrum antibody FHA3 targeting influenza A virus hemagglutinin (HA).Methods:According to the single-chain antibody fragment (scFv) sequence, the heavy chain (VH) and light chain (VL) variable regions of FHA3 were amplified by PCR and a recombinant plasmid pFRT-IgG1κ-FHA3 was constructed by linking the expression vector pFRT-IgG1κ. FHA3 was expressed in the ExpiCHO system and purified by affinity purification. The binding activity of FHA3 to influenza A virus HA was detected by ELISA. The neutralizing activity of FHA3 was detected in vitro by infecting host cells with pseudovirus. Results:SDS-PAGE showed that high-purity FHA3 was obtained. FHA3 could bind to H1N1 HA, H2N2 HA, H3N2 HA, H5N1 HA, H7N9 HA and H9N2 HA in a concentration-dependent manner. FHA3 had good neutralizing activity in vitro that was it could effectively block the invasion of H5N1 and H7N9 pseudoviruses into target cells at a low concentration of 5 μg/ml and H1N1 pseudovirus at 0.012 5 μg/ml. Conclusions:A broad spectrum antibody targeting HA protein of influenza A virus with neutralizing activity in vitro was obtained.
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Objective:To prepare and identify a functional antibody FNA1 targeting the neuraminidase (NA) of influenza A virus N1 subtype.Methods:According to single-chain antibody fragment (scFv) sequence, the heavy chain and light chain variable region sequences of FNA1 were synthesized, and the recombinant expression plasmid pFRT-IgG1κ-FNA1 was constructed by linking the expression vector pFRT-IgG1κ. The FNA1 antibody was expressed in ExpiCHO cells and purified using affinity purification technique. The binding ability of FNA1 to the target proteins, influenza A virus N1 subtype NA antigens, was detected by ELISA. Flow cytometry was performed to analyze the binding ability of FNA1 to the NA antigens expressed on the surface of cell membrane. The in vitro activity of FNA1 against NA was evaluated by infecting 293T cells with pseudovirus. Results:Protein electrophoresis showed that FNA1 with high purity was obtained. FNA1 specifically recognized and bound to N1 subtype NA antigens in a concentration-dependent manner. FNA1 could effectively block NA activity by binding to N1 subtype NA protein expressed on the surface of cell membrane, thus inhibiting the release of packaged pseudovirus from cell surface and further inhibiting target cell infection.Conclusions:An antibody FNA1 targeting influenza A virus N1 subtype NA with in vitro functional activity was obtained.
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Objective To examine whether Tim-3 plays a protective role in paraquat poisoning induced excessive immune response and tissue damage based on the critical roles of Tim-3 controlling inflammatory response.Methods A paraquat poisoning model was established in wild type and in Tim-3 transgenic C57BL/6 mice by intraperitoneal injection of paraquat (40 mg/kg) .In addition, C57BL/6 mice with paraquat poisoning were injected with Tim-3 soluble protein( sTim-3) or control protein to see the effect of Tim-3 blocking on the progression of paraquat poisoning.Samples were collected at 6 and 24 h after paraquat injection respectively and were examined for tissue damage, cytokine expression and paraquat metabolism.Results After paraquat poisoning, there was significantly attenuated tissue damage in the lungs and kidneys and decreased TNF-α,IL-6 and IL-1 beta expression in the PBMCs or in the serum from Tim-3 transgenic mice compared to wild type mice.The serum concentration of paraquat in Tim-3 transgenic mice was also significantly decreased.However, in sTim-3 treated paraquat poisoning mice, there was significantly increased cytokine expression and tissue damage compared to control protein treated mice.The in vitro data showed that Tim-3 signaling negatively regulated macrophages mediated inflammatory response.Conclusion Tim-3 plays a critical role in maintaining the homeostasis after paraquat poisoning. Further investigation on the regulatory roles of Tim-3 in inflammation will shed new light on the pathogenesis of paraquat poisoning and provide new therapeutic strategies.
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Objective To ascertain whether estrogen could induce B cell to produce interleukin(IL)-10. Methods C57BL/6 splenic B cells were purified by magnetic activated cell sorting(MACS)method,followed by estrogen treatment for 3 days. The secretion of IL-10 from cultured cell supernatant was tested by ELISA technique. The abundance of mRNA for IL-10、PD-L1 and RBM47 in B cells with estrogen treatment was tested by real-time PCR method. The intracellular IL-10 expression and the surface PD-L1 expression of treated B cells were tested by fluorescence activated cell sorting(FACS)method. And the expression of RBM47 in B cells by estrogen treatment was tested using Western blotting method. Results Estrogen could induce B cell to produce IL-10 in a dose-dependent manner. Estrogen treatment could increase the percentage of IL-10+B cells,the abundance of mRNA for IL-10,PD-L1 and RBM47 in B cells,as well as the expression of PD-L1 on B cell surface. Furthermore,our experimental result indicated the upreg?ulation of RBM47 expression in B cells by estrogen treatment. Conclusion Estrogen treatment in vitro can induce the upregulation of IL-10+regulatory B cells(Breg). Upregulation of RBM47 in the treated B cells might participate in this process by stabilizing IL-10 mRNA.
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As a targeted drug,monoclonal antibodies have been successful in tumor therapy. Thus,antibodies and related products are the fastest-developing biological agents. There are currently more than 40 monoclonal antibodies in the market that have been approved by the FDA,half of which are used to treat cancer. In recent years,a new generation of antibody drugs,such as human anti?body,glyco-engineered antibody,bispecific antibody,antibody-drug conjugates and immune check?point blockade antibody,have successfully cured various malignant tumors. In this paper,the history of antibody treatment for cancer,and the development and prospect of anti-tumor antibodies have been reviewed.
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B cells not only can regulate the immune responses by producing antibody, presenting antigens to target immune cells, but also have the function of immune suppression. A small quantity of regulatory B ( Breg) cells in vivo is capable of performing regulatory functions by producing of inhibitory cytokines,such as interleukin -10, or by direct interaction with other immune cells. In vivo, Breg can maintain immune tolerance and inhibit excessive inflammatory responses efficiently. Clinical studies indicate that Breg are associated with some autoimmune diseases, cancers, infections, and transplantation tolerance. The review focuses on molecules associated with the differentiation and function of the Breg. And also, we discuss the mechanisms and the relations of Breg to clinical diseases.
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The interleukin-12 (IL-12) family, including IL-12, IL-23, IL-27,and IL-35, is characterized by unique structures and molecular partners.This is the only family of heterodimeric cytokines, which endows them with a unique set of connections and functional interactions.They not only play an important role in the regulation of inflammation, but are closely related to various autoimmune diseases.Here we discuss the structural aspects of these cytokines and their effect on some autoimmune diseases.
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Due to the large population and relatively closed space environment , the subway system is vulnerable to bioterrorist attacks.This paper analyzes the technological response measures against subway bioterrorism in the United States, including Detect to Protect program of Department of Homeland Security (DHS) and PROTECTS program of Depart-ment of Energy ( DOE) .We also put forward some proposals on how to improve China′s capability of prevention of and response to subway bioterrorism .
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Biosecurity is defined as effectively responding to biological damage associated with various destructive fac -tors and threats ,maintaining and protecting national interests ,security and public health in the era of globalization .This pa-per analyzes the overall situation of biosecurity capability building since the SARS outbreak in 2003 before concluding that remarkable progress has been made in China , but the gap remains great compared with the need of national security envi -ronment and the capacity building of developed countries .This paper outlines four considcrations regarding the development of biosecurity research strategic planning and offer eight tips on strengthening research on biosecurity technology in China .
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Biosecurity is an important component of national security and an important guarantee for national revival and the realization of China's dream.However China is facing increasingly serious biological threats .Biosecurity capability build-ing has some problem .For exanyple ,people have a vague idea about the relationship between different biological threats ,the duties and rights of civil-military integration development , the balance between sustainable development and emergency pre-vention and control capacity-building, multidisciplinary convergence of biosecurity capacity-building, and about ways to break down the technological blockade and market monopoly by the United States and other developed countries .
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Objective To study the intrinsic relationships between the binding energy of the antibody light and heavy chains and the conformational characteristics , physical and chemical properties , and to establish a corresponding mathemat-ical model and evaluate the thermal stability of the antibody molecules , which contribute to the antibody design , optimiza-tion and affinity maturation .Methods Based on bioinformatics and computational biology methods , the antibody′s structur-al information with the crystal diffraction data was analyzed .The conformational character of the variable domain of the antibody was studied using distance geometry and computer graphics technology .With the aid of the intermolecular hydrogen bond formation theory and the reaction free energy theory , the dynamic structure and energy characteristics be-tween the heavy and light chain variable regions of the antibody were studied .Furthermore , using nonlinear fitting and regression analysis, a mathematical model was set up .Results According to simulation and statistic analysis , there was a linear relationship between the binding energy and the number of the intermolecular hydrogen bonding , Van der Waals interaction of the heavy and light chains of the antibody .There was polynomial correlation between the binding energy and the physicochemical properties of the antibody .Using the frequency of amino acid position and the established model , the humanized anti-ricin antibody , which could not obtain the stable engineering cell line , was evaluated and optimized .The stable engineering cell line of the humanized anti-ricin antibody was obtained in the experiment .Conclusion The self structure of the antibody variable region ( conformation and physicochemical properties ) has much effect on its stability . The antibody stability can be improved by structural optimization .
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Antibody drug conjugates(ADC),the new generation of antibody technology,combine the target-specificity of mon-oclonal antibody(mAb)and the highly active cell-killing drugs,taking advantages of the best characteristics out of both components. ADC consist of three different components:antibody,linker and cytotoxic drugs (also frequently referred as payload).The antibody component,the vector to selectively deliver a highly toxic drug to the cancer cell,plays an important role in the development of the ideal ADC.This paper reviews the development and current situations,features,types and target selection of the naked antibody,and the development of different targets antibodies existing at present.
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Objective To develop a human Tim-3 specific monoclonal antibody and evaluate its biological activity and possible use in clinical diseases associated with dysregulated Tim-3 expression .Methods The BALB/c mice were immu-nized by conventional method, and positive clones were used to develop anti-human Tim-3 antibody, the binding and neutralization activities of which in vitro and in vivo were investigated.Results ①A monoclonal antibody (clone L3D) which could specifically bind to human Tim-3 protein in ELISA assay was obtained and the subtype of the monoclonal antibody was IgG2a .②Flow cytometry indicated that the monoclonal antibody could bind to Tim-3 expressed in human U937 cells.This antibody also showed a cross activity to mice′Tim-3.③The monoclonal antibody inhibited the apoptosis of THP1 cells induced by Gal-9, the ligand of Tim-3.④Injection of Tim-3 antibody exacerbated sepsis in mice as marked by the decreased survival rate and increased expression of pro-inflammatory cytokines .Conclusion An anti-human Tim-3 monoclonal antibody is successfully obtained.The excellent binding and neutralization activities of this antibody enable it to be widely used in clinical diseases associated with deregulated Tim-3 expression .
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Based on situation assessment of the core areas of biosecurity , this paper summarizes three typical features of biosecurity that make it different from traditional safety , abd proposes that biosecurity be regarded as a living-project of a country .A mature and powerful country has to possess sufficient capacity to ensure biosecurity .This study also analyzes the national biosecurity strategyies and practices of the United States ,which has established a national-level capacity building strategy and roadmap with clear objectives ,specified the responsibilities of each federal agency , and regulations linked up with strategic planning .Biosecurity in China is at the crossroads where crisis coexists with opportunity , making it urgent to establish the national biosecurity strategy .
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Human cytomegalovirus glycoprotein complex Ⅱ (gC Ⅱ ) consists of two glycoproteins, gM and gN. Although gC Ⅱ specific IgG purified from HCMV positive patient sera can neutralize HCMV, there has been no report on the generation of virus-neutralizing antibodies by immunizing with one epitope of gM. The epitope, termed MAD, was screened from random phage peptide library by subtractive strategy. The peptide sequence of MAD was highly homologous with 32~38 amino acids of HCMV gM. Mice immunized with MAD coupled with keyhole limpet hemocyanin (KLH) could produce specific antibodies against MAD, and the antibodies obtained could bind not only native HCMV particles, but also the recombinant gM30～78 peptide. ELISA analysis results showed that MAD could specifically bind HCMV-positive human serum samples. Virus-neutralizing assay results demonstrated that the antibodies against MAD could inhibit HCMV strain AD169 entering the human embryonic lung cells. The results suggested that MAD could be used as a new potential protective antigen in the development of HCMV vaccine.
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Objective To establish a stable cell line secreting human IgE Cε2-4 protein, and in-vestigate the binding capacity of receptor FcεR Ⅰ Methods The E24 gene was derived from SKO-O07 cell line, and was then cloned into pcDNA3.1 (+) (signal peptides were synthesized and fused at the 5'-end of E24 gene) or pCMV-L vector. After transient transfection into 293T cell, the secreted F24 protein was ana-lyzed by sandwich ELISA. The best vector was chosen to be transfected into CHO cells with LipofectAMI-NETM 2000 reagent. After being selected by G418 and subcloned three times by limited-dilution method, two stable cell lines were established. E24 gene was amplified by RT-PCR, and the E24 protein in the superna-tant was identified by ELISA. Besides, the binding capacity of FceR ⅠⅡ was analyzed by flow cytometry method. Results Three mammalian expression vector SP-E24-F3. 1, SP lI-E24-P3.1 and E24-PL were constructed and transient transfected to 293T cells. The output of E24 protein in the supernatant were 19.1, 19.4 and 8.7 μg/ml, respectively. Then the vector SP IX-E24-P3.1 was transfected into CHO cells. Final-ly, two single clones secreting E24 protein were stably obtained. The output of E24 were all at least 25 μg/ml. RT-PCR could detect the E24 gene from one of the two clones. Furthermore, flow cytometry results showed that E24 could bind the receptor in a dose-dependent manner. Conclusion Two stable cell line se- creting E24 protein were obtained, while E24 could specifically bind FcεR Ⅰ.
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Objective To design and express a novel peptide based on ricin toxin antibody in E. coli, and to evaluate its biological activity. Methods Based on the crystal structure of ricin toxin A chain (RTA) and the RTA-rRNA interact in the complex model, the steric conformation of RTA was theoretical modeled and its functional domain was preliminarily determined. The humanized single-domain RTA antibody was designed rationally by computer-guidod molecular design method. Its coding sequence was ob- tained by overlapping extension PCR, and cloned into the pET-32a vector. The fusion protein was then ex-pressed in E. coli BL21 (DE3), identified by Western blot, and purified with Ni-NTA agarose. The binding and neutralizing activity of this novel peptide for riein was evaluated by competitive ELlSA assay and MTT assay. Results A recombinant human single-domain antibody expressing a polypeptide against RTA in the CDR3 loop was designed. The fusion protein was successfully expressed in E. coll. The purified protein can bind to ricin, and neutralize its activity in SP2/0 viability assay. Conclusion The success of the novel pep-tide based on riein toxin antibody provides a novel method to develop new generation of ricin antagonists.
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Objective To explore the mechanism by which the anti-human P185erbB2 scFv-Fc-IL-2(HFI)modulates tumor surface molecules and activates immune effector cells in vitro. MethodsMTT assay was used to test the proliferation and the LAK-like cytotoxicity. Flow cytometry assay was used to test the expression of ICAM-1, Fas and erbB2 receptors in tumor cells and the expression levels of CD molecules FasL and LFA-1 in human PBMC. Antibody-dependent cell-mediated cytotoxicity(ADCC)mediated by HFI against SKOV3, MCF-7 and SGC-7901 tumor cells was explored hv LDH release assay. Results The expression levels of ICAM-1 and Fas on SKOV3 cell treated with HFI were upregulated, from 24.85％ and 0.53％ to 85.36％ and 59.19％ respectively, while the expression levels of erbB2 on SKOV3, MCF-7 and SGC-7901 tumor cells treated with HFI were downregulated, from 98.48％, 42.60％ and 36.66％ to 94.01％,30.95％ and 12.36％ respectively. HFI could significantly enhance the proliferation activity of human PBMC, and CD3+ CD8+ T cells and CD3- CD16+ CD56+ NK cells were elevated, from 24.37％ and 6.90％ to 38.80％ and 13.45％ respectively. The expression levels of CD25, LFA-1 and FasL were significantly enhanced from 3.99％, 86.52％ and 5.02％ to 12.96％, 99.06％ and 16.19％. The LAK-like cytotoxicity of human PBMC treated with HFI against SKOV3, MCF-7,SGC-7901 tumor cells was significantly improved:HFI was effective in mediating ADCC against SKOV3,MCF-7 and SGC-7901 tumor cells which expressed high,medium and low levels of erbB2,respectively,and HFI-induced ADCC was correlated with the degrees of erbB2 expression on the tumor cells. Conclusion The expression levels of ICAM-1 and Fas on SKOV3 cell treated with HFI are significantly upregulated. The expression levels of erbB2 on SKOV3, MCF-7 and SGC-7901 tumor cells treated with HFI are downregulated. HFI can significantly enhance the proliferation activity of human PBMC. The LAK-like eytotoxicity of human PBMC treated with HFI against tumor cells is significantly enhanced. HFI iS effective in mediating ADCC and the activity of HFI-induced ADCC is correlated with the degrees of erbB2 expression on the tumor cells.