Monoclonal antibody (mAb) is an important biological macromolecule and widely used in immune detection, in vitro diagnostics, and drug discovery. However, the inherent properties of mAb restrict its further development, such as high molecular weight and complex structure. Therefore, there is an urgent need to develop alternatives for mAb. Various types of miniaturized antibodies have been developed, among which the variable domain of immunoglobulin new antigen receptor (VNAR) is very attractive. The shark single-domain antibody, also known as shark VNAR, is an antigen-binding domain obtained by genetic engineering technology based on the immunoglobulin new antigen receptor (IgNAR) that naturally exists in selachimorpha. It has a molecular weight of 12 kDa, which is the smallest antigen-binding domain found in the known vertebrates at present. Compared with mAb, the shark VNAR exhibits various superiorities, such as low molecular weight, high affinity, tolerance to the harsh environment, good water solubility, strong tissue penetration, and recognition of the hidden epitopes. It has attracted wide attention in the fields of immunochemical reagents and drug discovery. In this review, various aspects of shark VNAR are elaborated, including the structural and functional characteristics, generating and humanization techniques, affinity maturation strategies, application fields, advantages and disadvantages, and prospects.
Animals ; Antibodies, Monoclonal ; immunology ; Antibodies, Monoclonal, Humanized ; immunology ; Antigens ; Epitopes ; metabolism ; Protein Domains ; immunology ; Receptors, Antigen ; chemistry ; immunology ; Sharks

This study is (1) to improve the stabilization of human scFv to rabies virus; (2) to prepare active human dsFv fragment; and (3) to evaluate the biological activities of dsFv. The dsFv V(H) and VL were separately expressed in PET22b(+)/BL21 (DE3), solublized and combined in appropriate molar ratio in refolding solution. The resultant dsFv fragments were evaluated for its protection against rabies virus, its affinity and stability, in reference to the cognate scFv. The dsFv was found to bind specifically to Vero vaccine of rabies virus. Compared to the scFv, the dsFv was more stable, had higher affinity, and was able to inhibit the infection of Rabies virus to Vero cell. This established a solid basis for the clinical application of dsFv to rabies virus.
Antibodies, Viral ; immunology ; Disulfides ; chemistry ; Humans ; Immunoglobulin Fragments ; immunology ; metabolism ; Immunoglobulin Variable Region ; immunology ; metabolism ; Rabies virus ; immunology

OBJECTIVETo develop a monoclonal antibody (mAb) directed to FVIII C2 domain and investigate its effect on FVIII activity.

METHODSFVIII C2 protein was expressed in E. coli and purified. A murine antihuman FVIII C2 domain mAb SZ-132 was developed by standard hybridoma technology and characterized. In coagulation assays, different concentrations of SZ-132 were incubated with freshly collected pooled human plasma and the residual activity of FVIII and activated partial thromboplastin time (APTT) were determined. The effects of SZ-132 on rhFVIII binding to purified human vWF, phosphatidylserine (PS) and platelets were assessed by enzyme linked immunosorbent assays (ELISA).

RESULTSSZ-132 could inhibit FVIII procoagulant activity in a dose-dependent manner within the concentrations of 0-25 microg/ml and the FVIII activity was completely inhibited on above 25 microg/ml. It could also prevent rhFVIII from binding to vWF, PS and platelets.

CONCLUSIONSSZ-132 is a neutralizing mAb against FVIII C2 domain and can inhibit FVIII procoagulant activity by preventing FVIII from binding to vWF and PS.

Animals ; Antibodies, Monoclonal ; biosynthesis ; immunology ; Antibodies, Neutralizing ; biosynthesis ; immunology ; Factor VIII ; immunology ; metabolism ; Humans ; Male ; Mice ; Mice, Inbred BALB C

OBJECTIVETo study the regulation of Fc receptor expression by immune complexes (ICs) on neutrophils and U937 cells.

METHODSIgA ICs, IgG1 ICs, IgG2 ICs, IgG3 ICs, IgG4 ICs, and IgM ICs were incubated with neutrophils or U937 cells for 1 h. Then their surface Fc receptors were stained by anti-Fc gammaR I, anti-Fc gammaR II , anti-Fc gammaR III, and anti-Fc alphaR I monoclonal antibodies and analyzed by fluorescent activated cell sorting (FACS).

RESULTSIgG1 ICs and IgG3 ICs up-regulated Fc gammaR II and Fc gammaR III on U937 cells, Fc gammaR I and Fc alphaR I on neutrophils. Almost all ICs down-regulated Fc gammaR II on neutrophils.

CONCLUSIONSICs can regulate Fc receptor expression on neutrophils and U937 cells, among which IgG1 ICs and IgG3 ICs are most effective.

Antibodies, Anti-Idiotypic ; immunology ; Antibodies, Monoclonal ; pharmacology ; Antigen-Antibody Complex ; immunology ; metabolism ; Antigens, CD ; immunology ; Humans ; Immunoglobulin A ; classification ; immunology ; Immunoglobulin G ; chemistry ; classification ; immunology ; metabolism ; Neutrophils ; metabolism ; Receptors, Fc ; biosynthesis ; genetics ; Receptors, IgG ; immunology ; U937 Cells ; immunology

Animals ; Antigens, CD ; immunology ; Cytokines ; metabolism ; Hepacivirus ; immunology ; Hepatitis C ; immunology ; prevention & control ; virology ; Hepatitis C Antibodies ; biosynthesis ; immunology ; Hepatitis C Antigens ; immunology ; Humans ; Killer Cells, Natural ; immunology ; T-Lymphocytes ; immunology ; metabolism ; T-Lymphocytes, Regulatory ; immunology ; metabolism ; Viral Proteins ; immunology

Infectious bursal disease virus(IBD) causes infectious bursal disease (IBD), which infects bursal of chicken and can evoke immune suppression. This study identified the antigenic epitopes of four McAbs to IBDV VP3(HRB-3F, HRB-7B, HRB-7C and HRB-10E)with pepscan. A set of 17 partially overlapping or consecutive peptides (P1-P17) spanning VP3 were expressed for epitope screening by pepscan. Finally, two antigenic epitopes, 109-119aa and 177-190aa of IBDV VP3, were identified by Western blot and ELISA. The peptides on epitopes could react with IBDV, and they had better immunnogenicity. The sequences of epitopes were compared with that of several other IBDV strains in the same region, and was found they were totally homologous. This study showed the two epitopes were novel conserved linear B cell epitopes on the VP3 of IBDV. This study provides basis for the development of immunity-based prophylactic, therapeutic and diagnostic measures for control of IBD and further for structural and functional analysis of IBDV.
Animals ; Antibodies, Monoclonal ; immunology ; Antibodies, Viral ; blood ; immunology ; Blotting, Western ; Capsid Proteins ; genetics ; immunology ; metabolism ; Enzyme-Linked Immunosorbent Assay ; Epitopes ; genetics ; immunology ; metabolism ; Immune Sera ; immunology ; Immunization ; Immunohistochemistry ; Infectious bursal disease virus ; genetics ; immunology ; metabolism ; Mice ; Mice, Inbred BALB C

Ebola virus (EBOV) causes outbreaks of a highly lethal hemorrhagic fever in humans and there are no effective therapeutic or prophylactic treatments available. The glycoprotein (GP) of EBOV is a transmembrane envelope protein known to play multiple functions including virus attachment and entry, cell rounding and cytotoxicity, down-regulation of host surface proteins, and enhancement of virus assembly and budding. GP is the primary target of protective immunity and the key target for developing neutralizing antibodies. In this paper, the research progress on genetic structure, pathogenesis and immunogenicity of EBOV GP in the last 5 years is reviewed.
Animals ; Antibodies, Viral ; immunology ; Ebolavirus ; genetics ; immunology ; physiology ; Glycoproteins ; genetics ; immunology ; metabolism ; Hemorrhagic Fever, Ebola ; immunology ; virology ; Humans ; Viral Envelope Proteins ; genetics ; immunology ; metabolism ; Virus Assembly

OBJECTIVEThe low rate of engraftment in children with beta-thalassemia has seriously restricted the popularity of the hematopoietic stem cell transplantation (HSCT). Panel reactive antibody (PRA) has been regarded as one of the important factors for the success of kidney transplantation. Poly-transfusion before transplantation is associated with the production of PRA. Also PRA is produced in the children with beta-thalassemia major who need poly-transfusion for life. PRA might be one of factors inducing the low rate of engraftment in children with beta-thalassemia. This study focused on observing the effect of PRA on the proliferation, differentiation, apoptosis and necrosis of cord blood CD34(+) cells in vitro by incubating the cord blood CD34(+) cells with serum containing PRA.

METHODSeven samples of cord blood were collected and the HLA typing for every sample was done. Seven sera positive for PRA and seven negative sera were selected respectively. Mononuclear cells (MNCs) were obtained by Ficoll-Hypaque density gradient centrifugation. CD34(+) cells were isolated from MNCs by positive selection using an immunomagnetic separation (CD34(+) progenitor cell isolation kit and auto-MACS). The CD34(+) cells of umbilical cord blood were incubated with the serum and complement in the following groups: A (absence of serum), B (presence of PRA positive serum), C (presence of PRA positive serum and complement), D (presence of complement), and E (presence of PRA negative serum). After incubation the samples were centrifuged and the supernatant was collected for LDH detection. At the same time the CD34(+) cells were harvested for assessing the expression of Annexin V and CD95 of the CD34(+) cells by flow cytometry and also for the detection of the DNA synthesis by (3)H-TaR incorporation. Meanwhile the cells were inoculated into the methylcellulose cultural system. The proliferation and hematopoietic potential of the CD34(+) cell of cord blood by the colony formation assay were detected on the day 10.

RESULTThe concentration of LDH in group A was (20.71 +/- 2.81) U/L, which was significantly lower than that in group B (64.28 +/- 5.12) U/L and group C (84.29 +/- 4.99) U/L. The concentration of LDH in group B was significantly lower than that in group C, while there were no significant differences in the concentration of LDH among groups A, D and E (P > 0.05). The cpm in group A was (22 629 +/- 3288), which was significantly higher than that in group B (4598 +/- 2178) and group C (1626 +/- 1192). And the cpm in group B was significantly higher than that in group C. There were no significant differences in the cpm among groups A, D and E (P > 0.05). On day 10 of culture, the total colonies, granulocyte-macrophage colony forming unit (CFU-GM), mixed colony forming unit (CFU-GEMM) and erythroid burst colony forming unit (BFU-E) in group A were significantly higher than that in group B and C. The total colonies, CFU-GM and CFU-GEMM in group B were significantly higher than those in group C. No significant differences were found in the total colonies, CFU-GM, CFU-GEMM and BFU-E among groups A, D and E (P > 0.05). There were no statistically significant differences in the CD95 and Annexin V expression among all the groups (P > 0.05).

CONCLUSIONPRA could impair the membrane, decrease the DNA synthesis, and inhibit the colony formation of CD34(+) cord blood cells, which could be strengthened by the presence of the complement at the given concentration in our study. PRA had no significant influence on the apoptosis of CD34(+) cells in vitro.

Antibodies ; immunology ; Antigens, CD34 ; Apoptosis ; immunology ; Cell Differentiation ; immunology ; Cell Proliferation ; Cells, Cultured ; Child ; Fetal Blood ; cytology ; immunology ; metabolism ; Flow Cytometry ; Humans ; Quorum Sensing ; immunology ; beta-Thalassemia ; immunology

Orientia tsutsugamushi, a causative pathogen of Scrub typhus, is a gram-negative intracellular bacterium. Outer membrane vesicles (OMVs) are produced from the membrane of bacteria and play many roles related to the survival of the pathogen. However, there have been no reports confirming whether O. tsutsugamushi indeed produce OMVs. O. tsutsugamushi boryong was cultured in ECV-304 cells for the purification of OMVs. Western blot analysis and immunoenrichment using anti-O. tsutsugamushi monoclonal antibody and electron microscopy were employed for identification and characterization of OMVs. We confirm the presence of OMVs derived from O. tsutsugamushi, and also found that those OMVs contain a major surface antigen of 56-kDa protein and variant immunogenic antigens.
Antibodies, Monoclonal/*immunology ; Antigens, Bacterial/*immunology ; Antigens, Surface/*immunology ; Cell Line ; Cell Membrane/immunology ; Humans ; Microscopy, Electron ; Orientia tsutsugamushi/*immunology/metabolism ; Scrub Typhus/diagnosis/microbiology ; Secretory Vesicles/*immunology

The emerging CR6261 antibody could neutralize several subtype influenza virus with high affinity, whose VH domain binds to the HA protein conserved domain. Therefore, it has drawn much attention as a potential broad-spectrum therapeutic antibody against influenza virus. In this study, we constructed the eukaryotic expression vectors pCR6261V(H), pCR6261V(H)-GFP and pCR6261scFv and screened the monoclonal cell lines that could stably express CR6261V(H), CR6261V(H)-GFP and CR6261scFv on the cell membrane. After influenza virus infecting the stable cell lines, the titers of viruses were tested by hemagglutination inhibition test. The result shows that the titers of viruses in CR6261scFv and CR6261V(H)-GFP stable expression cell lines decreased and there was no obvious discrimination between the CR6261V(H) expression cell line and the negative control, suggesting that CR6261V(H) and CR6261scFv expressing on the cell membrane could partly inhibit the virus infection. Though the effective inhibition strategy is undergoing, our research will provide new clues for the breeding of anti influenza transgenic animals.
Antibodies, Monoclonal ; immunology ; Antibodies, Viral ; chemistry ; immunology ; Antibody Specificity ; Cell Line ; Genetic Vectors ; Hemagglutinin Glycoproteins, Influenza Virus ; chemistry ; immunology ; metabolism ; Humans ; Influenza, Human ; immunology ; Orthomyxoviridae ; drug effects ; immunology ; Single-Chain Antibodies ; immunology