Objective To investigate antigen optimization of Shisa like protein 1 (SHISAL1) for preparing mouse anti-human SHISAL1 polyclonal antibody and to identify the specificity of the prepared antibody. Methods Bioinformatics was employed to predict the antigenic epitope region of SHISAL1 protein, and then a polypeptide composed of amino acid residues from the site of 28 to 97 of SHISAL1, termed SHISAL1-N, was selected as the antigen. The coding region of SHISAL1-N was cloned by molecular cloning technique, and then it was inserted into pET-28a to generate pET28a-SHISAL1-N recombinant plasmid. The two recombinant plasmids pET28a-SHISAL1-N and pET28a-SHISAL1 were transformed into BL21 (DE3) bacteria and induced to express by IPTG. The two proteins were purified and immunized to female Kunming mice, respectively. The specificities and sensitivities of the acquired antibodies were detected by Western blot analysis, immunoprecipitation and immunofluorescent cytochemical staining. Results pET28a-SHISAL1-N recombinant plasmid was successfully constructed, and the two fused proteins, SHISAL1 and SHISAL1-N, were induced to express. Moreover, two types of SHISAL1 mouse polyclonal antibodies, derived from SHISAL1-N and SHISAL1 antigens, were obtained. Western blot results showed that the antibody prepared from SHISAL1 antigen was less specific and sensitive compared with the antibody prepared from SHISAL1-N antigen which could specifically identify different endogenous SHISAL1 protein. Immunoprecipitation results showed that SHISAL1-N antibody could specifically pull down SHIISAL1 protein in hepatocellular carcinoma cells and immunofluorescence results demonstrated that SHISAL1-N antibody could specifically bind to SHISAL1 protein in the cytoplasm. Conclusion We have optimized the SHISAL1 antigen and prepared the mouse anti-human SHISAL1 polyclonal antibodies successfully, which can be used for Western blot analysis, immunoprecipitation and immunofluorescence cytochemical staining.
Animals ; Female ; Humans ; Mice ; Antibodies ; Antibody Specificity ; Blotting, Western ; Cloning, Molecular ; Epitopes/genetics*

Objective To investigate the preventive therapeutic effect and possible mechanism of single chain variable fragments chimeric protein (SD) of ovalbumin epitopes internalizing receptor DEC-205 antibody on food allergy in mice. Methods Mice were randomly divided to five groups (control, PBS, scFv DEC 100 μg, SD 50 μg, SD 100 μg) and treated for 24 hours before OVA administration. After challenge, the serum level of OVA-specific IgE, IgG1, IgG2a and IL-4 were detected by ELISA. Infiltration of eosinophils and mast cells in the jejunum was observed by HE staining and toluidine blue staining respectively. The bone marrow of tibia and femur was isolated and cultured to obtain immature dendritic cells(BMDCs), which were further treated with LPS (10 ng/mL), TSLP (50 ng/mL), scFv DEC protein (1000 ng/mL) and SD protein (10,100,1000)ng/mL for 24 hours, and the IL-10 level of supernatant was assayed by ELISA. Results Compared with PBS group, the number of SD-treated mice with diarrhea was markedly reduced. The difference in rectal temperature and the levels of serum OVA-specific IgE, IgG1, IgG2a and IL-4 decreased significantly after prophylactic administration of SD; The number of eosinophils and mast cells in jejunum also decreased significantly while the IL-10 level in the supernatant of BMDCs increased significantly after SD intervention. Conclusion SD mitigates experimental FA response by fosters the immune tolerance property of dendritic cells.
Mice ; Animals ; Ovalbumin ; Interleukin-10 ; Single-Chain Antibodies/genetics* ; Immunoglobulin E ; Epitopes/therapeutic use* ; Interleukin-4 ; Food Hypersensitivity/prevention & control* ; Immunoglobulin G ; Recombinant Fusion Proteins/genetics* ; Mice, Inbred BALB C ; Disease Models, Animal

New threats posed by the emerging circulating variants of SARS-CoV-2 highlight the need to find conserved neutralizing epitopes for therapeutic antibodies and efficient vaccine design. Here, we identified a receptor-binding domain (RBD)-binding antibody, XG014, which potently neutralizes β-coronavirus lineage B (β-CoV-B), including SARS-CoV-2, its circulating variants, SARS-CoV and bat SARSr-CoV WIV1. Interestingly, antibody family members competing with XG014 binding show reduced levels of cross-reactivity and induce antibody-dependent SARS-CoV-2 spike (S) protein-mediated cell-cell fusion, suggesting a unique mode of recognition by XG014. Structural analyses reveal that XG014 recognizes a conserved epitope outside the ACE2 binding site and completely locks RBD in the non-functional "down" conformation, while its family member XG005 directly competes with ACE2 binding and position the RBD "up". Single administration of XG014 is effective in protection against and therapy of SARS-CoV-2 infection in vivo. Our findings suggest the potential to develop XG014 as pan-β-CoV-B therapeutics and the importance of the XG014 conserved antigenic epitope for designing broadly protective vaccines against β-CoV-B and newly emerging SARS-CoV-2 variants of concern.
Angiotensin-Converting Enzyme 2 ; Antibodies, Neutralizing ; Antibodies, Viral ; COVID-19 ; Epitopes ; Humans ; SARS-CoV-2/genetics* ; Spike Glycoprotein, Coronavirus/genetics*

OBJECTIVE: To conduct eukaryotic expression of the leucine-rich repeat containing 15 (LRRC15), a differentially expressed protein in excretory secretory antigens of Taenia solium cysticercus, and predict its antigen epitope. METHODS: The molecular weight, stability, amino acid sequence composition, isoelectric point and T lymphocyte epitope of the LRRC15 protein were predicted using the bioinformatics online softwares ExPASy-PortParam and Protean. The full-length splicing primers were designed using PCR-based accurate synthesis, and the LRRC15 gene was synthesized. The recombinant pcDNA3.4-LRRC15 plasmid was constructed and transfected into HEK293 cells to express the LRRC15 protein. In addition, the LRRC15 protein was characterized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. RESULTS: The recombinant pcDNA3.4-LRRC15 plasmid was successfully constructed, which expressed the target LRRC15 protein with an approximately molecular weight of 70 kDa. Bioinformatics prediction with the ExPASy-PortParam software showed that LRRC15 was a hydrophilic protein, which was consisted of 644 amino acids and had a molecular weight of 69.89 kDa and an isoelectric point of 5.6. The molecular formula of the LRRC15 protein was C₃₀₇₃H₄₉₄₂N₈₄₆O₉₅₃S₂₈ and had an instability coefficient is 50.3, indicating that LRRC15 was an instable protein. Bioinformatics prediction with the Protean software showed that the dominant T-cell antigen epitopes were located in 292 to 295, 353 to 361, 521 to 526 and 555 to 564 amino acids of the LRRC15 protein, and the T-cell antigen epitopes with a high hydrophilicity, good flexibility, high surface accessibility and high antigenicity index were found in 122 to 131, 216 to 233, 249 to 254, 333 to 343, 358 to 361, 368 to 372, 384 to 386, 407 to 412, 445 to 450, 469 to 481, 553 to 564, 588 to 594, 607 to 617 and 624 to 639 amino acids. Following transfection of the recombinant pcDNA3.4-LRRC15 plasmid into HEK293 cells, SDS-PAGE and Western blotting identified LRRC15 proteins in cell secretory culture media, cell lysis supernatants and sediments. The LRRC15-His fusion protein was purified from the cell culture medium, and SDS-PAGE identified a remarkable band at approximately 70 kDa, while Western blotting successfully recognized the band of the recombinant LRRC15 protein. CONCLUSIONS The eukaryotic expression and antigen epitope prediction of the LRRC15 protein in the excretory secretory antigens of T. solium cysticercus have been successfully performed, which provides insights into further understandings of its biological functions.
Amino Acids ; Animals ; Antigens, Helminth/genetics* ; Cysticercus/genetics* ; Epitopes/genetics* ; Eukaryota ; HEK293 Cells ; Humans ; Leucine-Rich Repeat Proteins ; Membrane Proteins ; Taenia solium/genetics*

The aim of this study was to refold the OvisAries leukocyte antigen (OLA) class Ⅰ protein with peptides derived from sheeppox virus (SPPV) to identify SPPV T cell epitopes. Two pairs of primers were designed based on the published sequence of a sheep major histocompatibility complex Ⅰ to amplify the heavy chain gene of OLA Ⅰ α-BSP and the light chain gene of OLA Ⅰ-β₂m. Both genes were cloned into a pET-28a(+) expression vector, respectively, and induced with ITPG for protein expression. After purification, the heavy chain and light chain proteins as well as peptides derived from SPPV were refolded at a ratio of 1:1:1 using a gradual dilution method. Molecular exclusion chromatography was used to test whether these peptides bind to the OLA Ⅰ complex. T-cell responses were assessed using freshly isolated PBMCs from immunized sheep through IFN-γ ELISPOT with peptides derived from SPPV protein. The results showed that the cloned heavy chain and light chain expressed sufficiently, with a molecular weight of 36.3 kDa and 16.7 kDa, respectively. The protein separated via a Superdex^TM 200 increase 10/300 GL column was collected and verified by SDS-PAGE after refolding. One SPPV CTL epitope was identified after combined refolding and functional studies based on T-cell epitopes derived from SPPV. An OLA Ⅰ/peptide complex was refolded correctly, which is necessary for the structural characterization. This study may contribute to the development of sheep vaccine based on peptides.
Animals ; Capripoxvirus ; Epitopes, T-Lymphocyte/genetics* ; Peptides/genetics* ; Poxviridae Infections ; Sheep ; Sheep Diseases

The GapC protein of Streptococcus uberis located on the surface of bacteria is a protein with glyceraldehyde-3-phosphate dehydrogenase activity. It participates in cellular processes and exhibits a variety of biological activities. In addition, it has good antigenicity. The aim of this study was to predict the possible B-cell epitopes of the GapC protein and verify the immunogenicity of candidate epitope peptides. The gapC gene of S. uberis isolate RF5-1 was cloned into a recombinant expression plasmid pET-28a-GapC and inducibly expressed. The purified protein was used to immunize experimental rabbits to produce anti-GapC polyclonal antibodies. The three-dimensional structure and three-dimensional location of the GapC B-cell epitopes and the homology comparison of the GapC protein and its B-cell epitopes were carried out using bioinformatics softwares. The results showed that the 44-kDa GapC protein had a good immunological reactivity. Six linear and 3 conformational dominant B-cell epitopes against the GapC protein were selected and synthesized. Three dimensional analysis indicated that the selected peptides have better antigen epitope formation potential. Rabbit anti-GapC polyclonal antibodies were generated after immunized with the purified GapC protein, and the polyclonal antibodies were used to identify the epitope peptide by an indirect ELISA. The ELISA results showed that all of the 9 epitope peptides could react with anti-GapC polyclonal antibodies with varying titers. Among them, the epitope polypeptide ²⁶⁶AANDSYGYTEDPIVSSD²⁸² reacted with the polyclonal antibodies significantly stronger than with other epitope peptides. This study laid an experimental foundation for in-depth understanding of the immunological properties and utilizing effective epitopes of the GapC protein of S. uberis.
Animals ; Antigens, Bacterial/genetics* ; Bacterial Proteins/genetics* ; Epitopes, B-Lymphocyte/genetics* ; Mice ; Mice, Inbred BALB C ; Rabbits ; Streptococcus

OBJECTIVE: KRAS gene is one of the most common mutations of proto-oncogenes in human tumors, G12V is one of the most common mutation types for KRAS. It's challenging to chemically acquire the targeted drug for this mutation. Recent studies reported that this mutation peptides can form a neoepitope for T cell recognition. Our study aims to clone the T cell receptor (TCR) which specifically recognizes the neoepitope for KRAS G12V mutation and constructs TCR engineered T cells (TCR-T), and to investigate if TCR-Ts have strong antitumor response ability. METHODS: In this study, tumor infiltrating lymphocytes were obtained from one colorectal cancer patient carrying KRAS G12V mutation. Tumor-reactive TCR was obtained by single-cell RT-5' rapid-amplification of cDNA ends PCR analysis and introduced into peripheral blood lymphocytes to generate TCR-Ts. RESULTS: We obtained a high-affinity TCR sequence that specifically recognized the HLA-A^*11:01-restricted KRAS G12V_8-16 epitope: KVA11-01. KVA11-01 TCR-T could significantly kill various tumor cells such as PANC-1, SW480 and HeLa (overexpressing HLA-A^*11:01 and KRAS G12V), and secreting high levels of interferon-γ (IFN-γ). Non-specific killing experiments suggested KVA11-01 specifically recognized tumor cells expressing both mutant KRAS G12V and HLA-A^*11:01. In vivo assay, tumor inhibition experiments demonstrated that infusion of approximately 1E7 KVA11-01 TCR-T could significantly inhibit the growth of subcuta-neously transplanted tumors of PANC-1 and HeLa (overexpressing HLA-A^*11:01 and KRAS G12V) cells in nude mice. No destruction of the morphologies of the liver, spleen and brain were observed. We also found that KVA11-01 TCR-T could significantly infiltrate into tumor tissue and had a better homing ability. CONCLUSION KVA11-01 TCR-T cells can effectively target a variety of malignant tumor cells carrying KRAS G12V mutation through in vitro and in vivo assay. KVA11-01 TCR-T cells have excellent biological activity, high specificity of target antigen and homing ability into solid tumor tissue. KVA11-01 TCR-T is expected to be an effective treatment for patients with KRAS G12V mutant solid malignancies.
Animals ; DNA, Complementary ; Epitopes ; HLA-A Antigens ; Humans ; Interferon-gamma ; Mice ; Mice, Nude ; Mutation ; Neoplasms ; Proto-Oncogene Proteins p21(ras)/genetics* ; Receptors, Antigen, T-Cell/genetics*

Objective: To study the polymorphism in P66 and its human B-cell epitopes of Methods: Polymerase chain reaction (PCR) and sequencing were used to obtain the P66 sequences of 59 Chinese Results: Results showed that genetic and amino acid diversity presented in the 66 kD protein of all 59 Chinese strains, especially in Conclusion In P66 of 59 Chinese strains, polymorphisms were widely distributed. More importantly, the P66 amino acid sequences of
Bacterial Proteins/genetics* ; Borrelia burgdorferi/genetics* ; China ; Cluster Analysis ; Epitopes, B-Lymphocyte/genetics* ; Genetic Markers ; Genotype ; Humans ; Mutation ; Polymerase Chain Reaction ; Polymorphism, Genetic ; Porins/genetics*

To establish a method for identifying protein epitopes recognized by therapeutic monoclonal antibodies, the programmed death receptor-1 (PD-1) was selected as the target protein. Based on the alanine scanning strategy, a rapid expression method of antigen mutants combining site-directed mutagenesis with mammalian cell expression system was established, the conditions for eukaryotic expression element amplification and cell transfection expression were established. 150 PD-1 protein mutants were co-expressed, and the binding ability of these mutants to anti-PD-1 antibody Pembrolizumab was identified. The epitopes of Pembrolizumab were determined based on the binding ability of protein mutants to antibodies and combined with protein structure analysis, which was highly consistent with the reported crystal structure-based epitopes, indicating that this method is simple and accurate and can be used for epitope mapping of therapeutic monoclonal antibodies.
Animals ; Antibodies, Monoclonal ; Antigens ; Epitope Mapping ; Epitopes/genetics*

OBJECTIVETo eliminate the side effects of aluminum adjuvant and His-tag, we constructed chimeric VLPs displaying the epitope of EV71 (SP70) without His-tagged. Then evaluating whether the VLPs could efficiently evoke not only humoral but also cellular immune responses against EV71 without adjuvant.

METHODSThe fusion protein was constructed by inserting SP70 into the MIR of truncated HBcAg sequence, expressed in E. Coli, and purified through ion exchange chromatography and density gradient centrifugation. Mice were immunized with the VLPs and sera were collected afterwards. The specific antibody titers, IgG subtypes and neutralizing efficacy were detected by ELISA, neutralization assay, and EV71 lethal challenge. IFN-γ and IL-4 secreted by splenocytes were tested by ELISPOT assay.

RESULTSHBc-SP70 proteins can self-assemble into empty VLPs. After immunization with HBc-SP70 VLPs, the detectable anti-EV71 antibodies were effective in neutralizing EV71 and protected newborn mice from EV71 lethal challenge. There was no significant difference for the immune efficacy whether the aluminum adjuvant was added or not. The specific IgG subtypes were mainly IgG1 and IgG2b and splenocytes from the mice immunized produced high levels of IFN-γ and IL-4.

CONCLUSIONThe fusion proteins without His-tagged was expressed and purified as soluble chimeric HBc-SP70 VLPs without renaturation. In the absence of adjuvant, they were efficient to elicit high levels of Th1/Th2 mixed immune response as well as assisted by aluminum adjuvant. Furthermore, the chimeric VLPs have potential to prevent HBV and EV71 infection simultaneously.

Adjuvants, Immunologic ; Animals ; Antibodies, Neutralizing ; Antibodies, Viral ; blood ; Enterovirus A, Human ; genetics ; Enterovirus Infections ; immunology ; virology ; Epitopes ; immunology ; metabolism ; Escherichia coli ; metabolism ; Female ; Immunity, Cellular ; Immunity, Humoral ; Mice ; Recombinant Fusion Proteins ; immunology