Monoclonal antibodies have become the main type of antibody drug because of their high specificity and strong affinity to antigen. However, with the intensive study of the natural monoclonal antibody, many defects have faced, such as the limit times of binding to antigen, the unanticipated antibody clearance and antigen accumulation. Therefore, studies are no longer limited to the natural antibody screening, but rather to improve the efficiency of antibody drugs by engineering. In recent years, the bottlenecks in the development of conventional antibody have been solved effectively since the discovery of a novel recycling antibody. Recycling antibody binds to an antigen in plasma and dissociates from the antigen in endosome, thus maximizing the use of antibody and reducing antigen-mediated antibody clearance and antibody-mediated antigen accumulation. In addition, recycling antibodies can enhance the affinity with Fc receptors through further Fc modification. This paper reviews the research progress of circulating antibodies, including its characteristics, transformation methods and prospects.
Antibodies, Monoclonal ; immunology ; Antigens ; Endosomes ; Protein Binding ; Receptors, Fc

Animals ; Binding Sites ; Capsid ; chemistry ; immunology ; metabolism ; Escherichia coli ; genetics ; metabolism ; Gene Expression ; HIV-1 ; chemistry ; immunology ; Humans ; Mice ; Myxovirus Resistance Proteins ; chemistry ; immunology ; metabolism ; Protein Binding ; Protein Multimerization ; Protein Structure, Tertiary ; Recombinant Proteins ; chemistry ; immunology ; metabolism

The role of Mac-1 as a receptor for Bordetella bronchiseptica infection of alveolar macrophages (AMphi) was examined using 6 strains (2 ATCC and 4 pathogenic field isolates) to assess B. bronchiseptica binding, uptake and replication in primary porcine AMphi. All B. bronchiseptica strains were rapidly killed by porcine serum in a dose- and time-dependent manner. However, heat-inactivated porcine serum (HIS) did not demonstrate any bacterial-killing activity, suggesting that complement may have a direct killing activity. All field isolates were more resistant to direct complement-mediated B. bronchiseptica killing. The uptake of B. bronchiseptica into AMphi was inhibited approximately 50% by antiMac-1 monoclonal antibodies in the medium. However, B. bronchiseptica phagocytosed in the presence of serum or HIS was not altered by anti-Mac-1 antibodies although more bacteria were internalized by addition of serum or HIS. These data suggest that Mac-1 is a target for direct uptake of B. bronchiseptica via opsoninindependent binding. The phagocytosed B. bronchiseptica, either via direct or serum-mediated binding, were efficiently killed by AMphi within 10 hr postinfection. This demonstrates that Mac-1-mediated B. bronchiseptica uptake is a bacterial killing pathway not leading to productive infections in AMphi.
Animals ; Antibodies, Bacterial/blood/immunology ; Bordetella bronchiseptica/*immunology ; Macrophage-1 Antigen/*immunology ; Macrophages, Alveolar/*immunology ; Phagocytosis ; Protein Binding ; Swine/*immunology/*microbiology

OBJECTIVETo understand if the Neuraminidase (N1) of Influenza A virus at the surface of yeast-displaying system, eukaryotic expression system and the infected cells could be used for anti-NA Abs screening, their activities and bindings to five candidate Abs were assayed.

METHODSThe surface NA expression was obtained by transfecting by recombinant NA constructors with specific tag-labels or live virus infection. The functional activity was measured by the fluorescent assay. Their bindings to the Abs were detected by flow cytometry.

RESULTSThe surface NAs presenting on the yeast-displaying system and eukaryotic expression system exhibited functional NA activities as the NA at the surface of virus-infected cells which showed affinities to Ab1, 4, and 5. The same bindings to Abl and 5 were found in the surface NA expressed by eukaryotic expression system while minor binding was observed in the yeast displayed-NA.

CONCLUSIONThe epitopes of yeast-displayed NA may be different from the NAs present at eukaryotic expression system and the infected cells which more likely suitable for the screening of anti-NA Abs.

Antibodies ; immunology ; Antigens, Surface ; genetics ; immunology ; Cell Line ; HEK293 Cells ; Humans ; Influenza A virus ; genetics ; immunology ; Neuraminidase ; genetics ; immunology ; Protein Binding ; Recombinant Proteins ; genetics ; immunology

Human noroviruses (huNoVs) recognize histo-blood group antigens (HBGAs) as attachment factors, in which genogroup (G) I and GII huNoVs use distinct binding interfaces. The genetic and evolutionary relationships of GII huNoVs under selection by the host HBGAs have been well elucidated via a number of structural studies; however, such relationships among GI NoVs remain less clear due to the fact that the structures of HBGA-binding interfaces of only three GI NoVs with similar binding profiles are known. In this study the crystal structures of the P dimers of a Lewis-binding strain, the GI.8 Boxer virus (BV) that does not bind the A and H antigens, in complex with the Lewis b (Le(b)) and Le(y) antigens, respectively, were determined and compared with those of the three previously known GI huNoVs, i.e. GI.1 Norwalk virus (NV), GI.2 FUV258 (FUV) and GI.7 TCH060 (TCH) that bind the A/H/Le antigens. The HBGA binding interface of BV is composed of a conserved central binding pocket (CBP) that interacts with the β-galactose of the precursor, and a well-developed Le epitope-binding site formed by five amino acids, including three consecutive residues from the long P-loop and one from the S-loop of the P1 subdomain, a feature that was not seen in the other GI NoVs. On the other hand, the H epitope/acetamido binding site observed in the other GI NoVs is greatly degenerated in BV. These data explain the evolutionary path of GI NoVs selected by the polymorphic human HBGAs. While the CBP is conserved, the regions surrounding the CBP are flexible, providing freedom for changes. The loss or degeneration of the H epitope/acetamido binding site and the reinforcement of the Le binding site of the GI.8 BV is a typical example of such change selected by the host Lewis epitope.
Binding Sites ; Blood Group Antigens ; chemistry ; immunology ; Caliciviridae Infections ; immunology ; virology ; Crystallography, X-Ray ; Epitopes ; chemistry ; immunology ; Evolution, Molecular ; Humans ; Lewis Blood-Group System ; chemistry ; immunology ; Norovirus ; chemistry ; immunology ; pathogenicity ; Protein Binding ; Viral Proteins ; chemistry ; immunology

OBJECTIVETo prepare a monoclonal antibody against human telomeric repeat binding factor 1 (TRF1) protein and explore its biological characteristics.

METHODSBALB/c mice were immunized with GST-TRF1(33-277) fusion protein for the preparation of monoclonal antibody by hybridoma technique. The obtained antibody was used for clinical assay by Western-blot and immunohistochemical staining.

RESULTSOne strain of hybridoma was obtained. It was confirmed by Western-blot that the antibody specifically recognized the 60 kD TRF1 protein. Immunohistochemical staining of the antibody showed that TRF1 protein located in the cytoplasm of epithelial cells and bone marrow cells.

CONCLUSIONA TRF1 monoclonal antibody, with high specificity was developed. It is useful for detection of TRF1 protein in tissue specimens.

Animals ; Antibodies, Monoclonal ; immunology ; Blotting, Western ; Female ; Humans ; Hybridomas ; immunology ; Immunohistochemistry ; Mice ; Mice, Inbred BALB C ; Recombinant Fusion Proteins ; immunology ; Telomeric Repeat Binding Protein 1 ; analysis ; genetics ; immunology

Acrosin ; immunology ; isolation & purification ; Humans ; Male ; Membrane Proteins ; immunology ; isolation & purification ; Protein Binding ; Spermatozoa ; metabolism ; Zona Pellucida ; metabolism

OBJECTIVETo study the feasibility of delivering viral gene vector from a collagen-coated polyurethane (PU) film through a mechanism involving monoclonal antiviral antibody tethering.

METHODSAnti-adenoviral monoclonal antibodies were covalently bound to the collagen-coated PU surface. These antibodies enabled tethering of replication defective adenoviruses through highly specific antigen-antibody affinity. The PU film-based gene delivery using antibody-tethered adenovirus encoding green fluorescent protein (GEP) was tested in rat arterial smooth muscle cell (A10 cell) culture in vitro. The virus binding stability was studied by incubating the collagen-coated PU film in PBS solution at 37 degrees C for 20 days, followed with A10 cell cultures with the incubated films and the corresponding buffer solution.

RESULTSPU films with antibody-tethered adenovirus encoding GFP demonstrated efficient and highly localized gene delivery to A10 cells. Virus binding was stable for at least 10 days at physiological conditions, more than 77% of the originally bound virus remained in the film after 15 day's incubation.

CONCLUSIONGene delivery using PU film-based anti-viral antibody tethering of vectors exhibited potentials of applications in a wide array of single or multiple therapeutic gene strategies, and in further stent-based gene delivery therapeutic strategies.

Adenoviridae ; genetics ; Antibodies, Monoclonal ; immunology ; Antibody Specificity ; immunology ; Gene Transfer Techniques ; Genetic Therapy ; Genetic Vectors ; Humans ; Polyurethanes ; chemistry ; Protein Binding

A20 was originally identified as a TNFα-induced protein 3 (TNFAIP3), a key regulator of inflammation signalling pathways, as well as a NF-κB inhibitor. It plays a critical role in regulation of innate and adoptive immunity. Recently, A20 has also been proposed to function as a tumor suppressor. Lacking A20 gene is involved in inflammation-mediated autoimmune disease and tumorigenesis in several human B-cell lymphomas. Current advance concerning the feature of A20 expression in immune cells, the biological function, the immune regulated function in native immunity, humoral and cellular immunity, the inactivation of A20 in lymphocytic malignancies and the polymorphism and abnormal expression of A20 in autoimmune disease indicate that the clinical significance of A20 should be worthy to recognize and to be further employed in induction of immune tolerance, antitumor immuno-regulated therapy and antiviral immunotherapy and so on.
Adaptive Immunity ; Autoimmune Diseases ; immunology ; DNA-Binding Proteins ; immunology ; Genes, Tumor Suppressor ; Humans ; Inflammation ; immunology ; Intracellular Signaling Peptides and Proteins ; immunology ; NF-kappa B ; immunology ; Nuclear Proteins ; immunology ; Tumor Necrosis Factor alpha-Induced Protein 3 ; Tumor Necrosis Factor-alpha ; immunology

Proteins of the complement system are known to interact with many charged substances. We recently characterized binding of C1q and factor H to immobilized and liposomal anionic phospholipids. Factor H inhibited C1q binding to anionic phospholipids, suggesting a role for factor H in regulating activation of the complement classical pathway by anionic phospholipids. To extend this finding, we examined interactions of C1q and factor H with lipid A, a well-characterized activator of the classical pathway. We report that C1q and factor H both bind to immobilized lipid A, lipid A liposomes and intact Escherichia coli TG1. Factor H competes with C1q for binding to these targets. Furthermore, increasing the factor H: C1q molar ratio in serum diminished C4b fixation, indicating that factor H diminishes classical pathway activation. The recombinant forms of the Cterminal, globular heads of C1q A, B and C chains bound to lipid A and E. coli in a manner qualitatively similar to native C1q, confirming that C1q interacts with these targets via its globular head region. These observations reinforce our proposal that factor H has an additional complement regulatory role of down-regulating classical pathway activation in response to certain targets. This is distinct from its role as an alternative pathway down-regulator. We suggest that under physiological conditions, factor H may serve as a downregulator of bacterially-driven inflammatory responses, thereby fine-tuning and balancing the inflammatory response in infections with Gram-negative bacteria.
Binding, Competitive ; immunology ; Complement Activation ; immunology ; Complement C1q ; chemistry ; immunology ; metabolism ; Complement C4b ; analysis ; Complement Factor H ; chemistry ; immunology ; metabolism ; Complement Pathway, Classical ; immunology ; Escherichia coli ; immunology ; metabolism ; Humans ; Iodine Radioisotopes ; Isotope Labeling ; Lipid A ; immunology ; metabolism ; Liposomes ; immunology ; metabolism ; Protein Binding ; immunology ; Recombinant Proteins ; chemistry ; immunology ; metabolism ; Substrate Specificity