This study is designed to address the development, synthesis, and screening of non-animal-derived nanoantibody libraries. Furthermore, it seeks to elucidate the impact of framework region selection and complementarity-determining region (CDR) design on the characteristics of synthesized nanoantibody libraries. These investigations aim to establish a robust theoretical and technical foundation for enhancing the efficacy, diversity, and practical applicability of synthetic nanoantibody libraries. In this study, a new framework (IGHV3S65*01-IGHJ4*01) was identified based on the high-throughput sequencing results of natural nanobodies, and degenerate primers were designed based on the frequency of amino acids at each position in the complementarity-determining region (CDR) region to synthesize the coding fragments of nanobodies by overlap PCR. After 40 times of electro-transformation, a single-frame synthesized nanobody library (SS-Library) containing 6×10⁹ clones was obtained, and the titer of the library was demonstrated to be 10¹³ PFU/mL after rescue by the helper phage M13K07. Random 48 single colonies were picked for PCR, which revealed an insertion rate of 95.8%. Sanger sequencing results showed that 38 clones had complete sequences, none of which showed cysteines or stop codons, and no identical sequences appeared, suggesting that the library had higher diversity. The library was screened and validated with three antigens, including bovine serum albumin (BSA), acetylcholinesterase (AchE), and immunoglobulin G (IgG). Finally, 2 nanobodies against BSA, 10 against AchE, and 15 against IgG were obtained. One positive clone of each antigen was singled out for recombinant expression, and the results showed that all the three nanobodies were expressed in a soluble form. The binding activity of recombinantly expressed nanobodies was evaluated using indirect enzyme-linked immunosorbent assay (ELISA) and bio-layer interferometry (BLI). The results demonstrated that the anti-AChE and anti-IgG nanobodies exhibited specific binding to their respective antigens, with affinity constants (KD) of 294 nmol/L and 250 nmol/L, respectively. The nanobody synthetic library preparation method proposed in this study is simple and easy to use with low preference, and it is expected to be a universal nanobody discovery platform for the preparation and development of lead specific nanobodies.
Single-Domain Antibodies/biosynthesis* ; Peptide Library ; Complementarity Determining Regions/immunology* ; Animals

To explore the association between T-cell receptor beta variable (TCR BV) complementarity determining region 3 (CDR3) spectratyping and CMV activation in the recipients of allogeneic hematopoietic stem cell transplantation (HSCT).Fluorescence quantitative PCR melting curve analysis was used to sequence 24 TCR BV families in 7 HSCT recipients and 3 healthy controls. CMV-pp65 antigenemia was measured by immunohistochemical staining. Plasma IgM specific for CMV was identified using ELISA. Relationship between TCR BV families and CMV activation was statistically analyzed.Twenty-four TCR BV families were expressed in 3 healthy controls, while TCR BV CDR3 sequencing results in 7 recipients turned out to be BV9, BV11, BV17, BV20 and so on. Amino acid sequence features were as follows:TCR BV9 contained "QVRGGTDTQ", TCR BV11 contained "VATDEQ" and "LGDEQ", TCR BV17 contained "IGQGNTEA", and TCR BV20 contained "VGLAANEQ". Five recipients suffered from pp65 antigenemia in 3 month after transplantation, and pp65-positive cells ranged from 2 to 15 per 5×10white blood cells. Three recipients were CMV-IgM positive. No significant differences were found in TCR BV families between pp65-positive recipients and pp65-negative recipients (all>0.05). But there was statistically significant difference in frequency of TCR BV11 between CMV-IgM negative recipients and CMV-IgM positive recipients (<0.05).T cell immune response was characterized by special TCR BV CDR3 spectratyping in HSCT recipients, and TCR BV11 expression may be associated with CMV activation.
Amino Acid Sequence ; Complementarity Determining Regions ; genetics ; immunology ; Cytomegalovirus ; genetics ; immunology ; Cytomegalovirus Infections ; genetics ; Genotype ; Hematopoietic Stem Cell Transplantation ; adverse effects ; Humans ; Lymphocyte Activation ; genetics ; Phosphoproteins ; Polymerase Chain Reaction ; Polymorphism, Genetic ; immunology ; Receptors, Antigen, T-Cell, alpha-beta ; genetics ; immunology ; Spleen ; T-Lymphocytes ; immunology ; virology ; Viral Matrix Proteins

To rapidly select potent anti-VSTM1-v2 scFv (single-chain antibody fragment) by construction and screening of a humanized scFv library in which a murine VH-CDR3 library was grafted onto a human scFv framework. A murine VH-CDR3 library was amplified from anti-VSTM1-v2 murine cDNA and grafted on human scFv (VH3-VK1) framework. Anti-VSTM1-v2 scFv templates were selected and enriched through ribosome display, TA-cloned into expression vector, and transformed into BL21 (DE3) for soluble expression of target scFv. A total of 1000 clones were randomly picked. Positive ones were first identified using colony PCR, indirect ELISA, Western blotting and then verified with sequencing and dose response ELISA. At last an anti-VSTM1-v2 humanized scFv with good binding affinity (EC50 = 21.35 nmol x L(-1)) was selected from the humanized library of 10(12) members generated in this study. This scFv antibody might have potential applications. This study provides a new approach for rapid screening of humanized antibodies.
Animals ; Complementarity Determining Regions ; genetics ; immunology ; Cytokines ; immunology ; Humans ; Immunoglobulin Fragments ; genetics ; immunology ; Immunoglobulin Heavy Chains ; genetics ; immunology ; Mice ; Peptide Library ; Protein Binding ; Receptors, Immunologic ; immunology ; Single-Chain Antibodies ; genetics ; immunology ; isolation & purification

OBJECTIVETo analyze the drift of T cell receptor (TCR) Vα and Vβ gene family CDR3 spectratype in response to ovarian carcinoma cells mediated by an anti-human ovarian carcinoma/CD3 bispecific single-chain antibody (BHL-1), and explore the mechanism of the bispecific single-chain antibody-mediated T cell immune response.

METHODSImmunoscopic spectratyping technique was used to analyze the TCR repertoire diversity (CDR3 spectratype distribution) of the T cells from 6 healthy donors before and after stimulation of the cells with human ovarian carcinoma in the presence of BHL-1. The predominant usage of TCR α and Vβ chain CDR3 was analyzed after the stimulation, and sequence analysis was performed for the CDR3 region of the monoclonal T cells.

RESULTSThe spectratypes of Vα and Vβ gene family TCR CDR3 region showed a Gaussian distribution before stimulation of the T cells from the 6 donors. After stimulation of the T cells, CDR3 spectratype drift occurred in the T cells, and some TCR Vα and Vβ families showed an anomalous and oligoclonal expansion. Different CDR3 sequences of the Vα and Vβ gene family TCR were found in the monoclonal T cells stimulated with BHL-1.

CONCLUSIONCDR3 spectratype drift occurs in TCR α and Vβ chains of T cells after stimulation with human ovarian carcinoma cells and BHL-1, indicating that the predominant usage of TCR Vα and Vβ families is associated with the specific T cell immune response mediated by BHL-1.

Antibodies, Bispecific ; immunology ; Cell Line ; Cell Line, Tumor ; Complementarity Determining Regions ; immunology ; Female ; Humans ; Monocytes ; immunology ; Ovarian Neoplasms ; immunology ; Receptors, Antigen, T-Cell, alpha-beta ; immunology ; Single-Chain Antibodies ; immunology

OBJECTIVETo analyze the characteristics of CDR3 of TCRbeta on CD8+ T cells in chronic hepatitis B patients.

METHODSEight patients with chronic hepatitis B (ALT more than 2 ULN) were enrolled in this study. CD8+ T cells were isolated from peripheral blood. RT-PCR was proformed to amplify the CDR3 of TCRbeta, and the PCR products were sequenced and analyzed.

RESULTSThe chronic hepatitis B patients showed obvious clonal expansion of T cell, and three perturbation patterns of T cell expansion were showed in the CDR3 of TCRbeta, including monoclonicity, oligoclonicity and skewed peak patterns. The number of perturbation families of CD8+ subpopulation was significantly higher than that of CD8- subpopulation (10.6+/-4.7 vs. 4.1+/-3.1, t = 6.619, P less than 0.01). In 3 out of 8 patients, the number of perturbation families of CD8+ subpopulation was also higher than that of PBMCs without depleting CD8+ subpopulation.

CONCLUSIONSThe characteristics of CDR3 of TCRbeta may help to understand the inflammatory response in CHB patients.

Adult ; CD8-Positive T-Lymphocytes ; immunology ; Complementarity Determining Regions ; genetics ; Genes, T-Cell Receptor beta ; Hepatitis B, Chronic ; blood ; immunology ; Humans ; Male ; Receptors, Antigen, T-Cell ; immunology ; Young Adult

This study was purpused to analyze the characteristics of T cell receptor repertoire in target organs of murine graft-versus-host after haploidentical bone marrow transplantation (hiBMT) and the molecular characteristics of complementarity determining region3 (CDR3) repertoires of monoclonal T cell in liver, skin and ileum in murine after hiBMT. Murine haploidentical BMT model was established, CDR3-size spectratyping was used to study TCRBV repertoires in recipient liver, skin, ileum, spleen and a group of CDR3 molecules was obtained from GVHD-target tissues. The results showed that GVHD occurred as early as days 14 after transplantation and was proven by histology in liver, skin and ileum. A number of new monoclonal and oligoclonal T cells emerged in GVHD-target tissue. 45 CDR3 molecules had six C'-terminal motifs, which obtained from liver, skin, ileum in different times after hiBMT. It is concluded that target organs of murine graft-versus-host disease after hiBMT emerged a number of clonal or oligoclonal T cells, part of this T cell clones commonly uses some conserved CDR3 motifs and may recognize similar antigen.
Amino Acid Sequence ; Animals ; Bone Marrow Transplantation ; Complementarity Determining Regions ; genetics ; Graft vs Host Disease ; genetics ; immunology ; Immunoglobulin Variable Region ; genetics ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Molecular Sequence Data ; Receptors, Antigen, T-Cell ; genetics

The cross reactivity of mimotopes of hepatitis C virus (HCV) hypervariable region 1 (HVR1) was investigated to obtain epitopes that have high cross reactivity. Five expression vectors encoding B cell mimotopes fused with Trx were constructed, and the mimotope proteins were purified. The cross reactivity of mimotope proteins with HCV positive sera was determined by ELISA. HCV pseudotype particles (HCVpp) were generated and applied to evaluate neutralization effects of the sera of BALB/c mice immuned with the mimotope proteins on infection of Huh7. 5 cells. Our data showed that the mimotope proteins (P1, P2, P5, P6, P8) could react to the HCV positive sera. The HCVpp infection inhibition of the sera of BALB/c mice immuned with P6 or P8 was detectable. These results suggest that the mimotopes may be valuable in the studies of anti-HCV infection and development of HCV vaccines.
Amino Acid Sequence ; Animals ; Complementarity Determining Regions ; immunology ; Cross Reactions ; Enzyme-Linked Immunosorbent Assay ; Epitopes ; Hepacivirus ; immunology ; Humans ; Mice ; Mice, Inbred BALB C ; Molecular Sequence Data

OBJECTIVETo study the CDR3 spectratyping and clonal expansion of T cells in the peripheral blood mononuclear cells (PBMCs) of patients with beta-mediterranean anemia patient undergoing allogeneic peripheral blood stem cell (PBSC) transplantation.

METHODSThe total RNA was isolated from the PBMCs of a nine-year-old boy with beta-mediterranean anemia before and after PBSC transplantation, and at the time of occurrence of graft-versus-host disease (GVHD). The CDR3 length was analyzed using immunoscope technique, and the characteristics of the T cell receptor (TCR) on the T cells with clonal expansion were examined by gene sequencing.

RESULTSThe 24 TCR BV CDR3 repertoire showed Gaussian distribution in the PBMCs isolated before the transplantation, and some of the TCR BV family CDR3 showed skewing in the PBMCs isolated 23 days after transplantation and at the onset of GVHD (28 days after transplantation), suggesting the clonal expansion of the donor PBSCs.

CONCLUSIONThe host PBMCs show muti-clonal expansion 23 days after PBSC transplantation, and in the stage of GVHD, some of the TCR BV family T cells show significant monoclonal expansion. Analysis of TCR CDR3 spectratyping and the molecular characteristics of specific TCR may help evaluate the immune reconstitution following the transplantation and indicate specific treatment for potential GVHD.

Child ; Complementarity Determining Regions ; genetics ; immunology ; Graft vs Host Disease ; etiology ; immunology ; Humans ; Male ; Peripheral Blood Stem Cell Transplantation ; adverse effects ; methods ; Receptors, Antigen, T-Cell, alpha-beta ; genetics ; immunology ; beta-Thalassemia ; immunology ; surgery

OBJECTIVETo observe the TCR V gamma gene repertoire diversity in the peripheral blood mononuclear cells of the patients with the chronic benzene poisoning.

METHODSComplementarity determining region 3 (CDR3) of TCR V gamma subfamily genes were amplified in 10 patients with the chronic benzene poisoning using RT-PCR. The PCR products were further analyzed by genescan to evaluate clonality of T cells. 8 healthy persons served as control.

RESULTSAll V gamma subfamilies were detected in the 8 healthy donors. (1.30 +/- 0.48) V gamma subfamilies were detected in 10 patients. The number of detectable V gamma subfamilies present in the patients with the chronic benzene poisoning was significantly lower than in the control group (P < 0.01). The most frequently used V gamma genes in clonally expanded T-cells were V gamma II.

CONCLUSIONSkewed distribution and clonal expansion of TCR V gamma subfamily T cells could be found in the patients with the chronic benzene poisoning. This is the first report of clonal expansion TCR V gamma T cells in patients with chronic benzene poisoning. The bias pattern of TCR V alpha T cells may be due to the immune cytotoxicity from benzene.

Adult ; Benzene ; poisoning ; Chronic Disease ; Complementarity Determining Regions ; genetics ; Female ; Humans ; Leukocytes, Mononuclear ; immunology ; Male ; Middle Aged ; Occupational Diseases ; genetics ; immunology ; Receptors, Antigen, T-Cell, gamma-delta ; genetics ; immunology ; Young Adult

OBJECTIVETo study the molecular characteristics of CDR3 repertoires of T cell receptor beta chain variable region (TCRBV) of T lymphocytic clones in leukemia recipients after allogeneic hematopoietic stem cell transplantation ( allo-HSCT).

METHODSRT-PCR was used to amplify 24 subfamily genes of TCRBV from peripheral blood (PB) lymphocytes in twenty-four leukemia patients underwent three kinds of allo-HSCT and in five normal donors as control. The PCR products were further analyzed by genescan to evaluate the clonality of BV subfamily and characteristics of CDR3 and calculate usage rate of BV subfamily. The monoclonal bands which associated with GVHD and CMV infection were obtained by denaturation polyacrylamide gel electrophoresis and sequenced. Comparison of the sequences of TCRBV CDR3 with other CDR3 sequences which associated with GVHD or CMV infection was reported.

RESULTS2 approximately 19 months after transplantation, there were 6 approximately 14 BV subfamilies expressed and the polyclonal expression reached 33% in nine patients underwent haploidentical bone marrow transplantation(HI-BMT). In five patients underwent matched unrelated peripheral blood stem cell transplantation ( MU-PBSCT), there were 10 approximately 15 BV subfamilies expressed of which 45% were poly-clones. In 10 patients underwent matched sibling bone marrow transplantation(MS-BMT), 10 approximately 16 BV subfamilies were expressed and more than 48% of them were poly-clones. Monoclones and oligo-clones existed in 24 BV subfamilies but no common one monoclone BV subfamilies was found. Immune reconstitution in patients underwent HI-BMT was later than that in other two groups. In 2 patients TCRBV was detected in 2m and 3m after allo-HSCT and found that there was a tendency of increasing usage of BV subfamilies and increasing expression of CDR3 polymorphism. Twenty three TCRBV CDR3 molecules associated with GVHD and CMV infection were compared each other by bioinformatics and found that different cases of the same BV subfamilies may share similarity in amino acid motif, while in different BV subfamilies none appeared to share the same amino acid motif.

CONCLUSIONIn 1.5 years after allo-HSCT, the usage of TCRBV subfamilies still restricted. Immune reconstitution in patients underwent HI-BMT was later than that in other two groups. TCRBV CDR3 molecules associated with GVHD and CMV infection showed that different cases of the same BV subfamilies may share similarity in amino acid motif, while in different BV subfamilies none of clones appeared to share the same amino acid motif.

Adolescent ; Adult ; Base Sequence ; Child ; Complementarity Determining Regions ; genetics ; metabolism ; Cytomegalovirus Infections ; immunology ; Female ; Graft vs Host Disease ; immunology ; Hematopoietic Stem Cell Transplantation ; Humans ; Leukemia ; immunology ; therapy ; Male ; Middle Aged ; Molecular Sequence Data ; Postoperative Period ; Receptors, Antigen, T-Cell, alpha-beta ; genetics ; metabolism ; T-Lymphocytes ; immunology ; metabolism ; Transplantation, Homologous