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

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

PURPOSE: To identify new immunogenic HLA-A*33;03-restricted epitopes from the human papillomavirus (HPV) 16 E7 protein for immunotherapy against cervical cancer. MATERIALS AND METHODS: We synthesized fourteen overlapping 15-amino acid peptides and measured intracellular interferon-γ (IFN-γ) production in PBMC and CD8+ cytotoxic T lymphocytes (CTLs) after sensitization with these peptides using flow cytometry and ELISpot assay. The immunogenicity of epitopes was verified using a ⁵¹Cr release assay with SNU1299 cells. RESULTS: Among the fourteen 15-amino acid peptides, E7₄₉₋₆₃ (RAHYNIVTFCCKCDS) demonstrated the highest IFN-γ production from peripheral blood mononuclear cells (PBMCs), and CD8+ CTLs sensitized with E7₄₉₋₆₃ showed higher cytotoxic effect against SNU1299 cells than did CD8+ CTLs sensitized with other peptides or a negative control group. Thirteen 9- or 10-amino acid overlapping peptides spanning E7₄₉₋₆₃, E7₅₀₋₅₉ (AHYNIVTFCC), and E7₅₂₋₆₁ (YNIVTFCCKC) induced significantly higher IFN-γ production and cytotoxic effects against SNU1299 cells than the other peptides and negative controls, and the cytotoxicity of E7₅₀₋₅₉- and E7₅₂₋₆₁-sensitized PBMCs was induced via the cytolytic effect of CD8+ CTLs. CONCLUSION: We identified E7₅₀₋₅₉ and E7₅₂₋₆₁ as novel HPV 16 E7 epitopes for HLA-A*33;03. CD8+ CTL sensitized with these peptides result in an antitumor effect against cervical cancer cells. These epitopes could be useful for immune monitoring and immunotherapy for cervical cancer and HPV 16-related diseases including anal cancer and oropharyngeal cancer.
Amino Acid Sequence ; CD8-Positive T-Lymphocytes/immunology/metabolism ; Epitopes/*immunology/therapeutic use ; Female ; *HLA-A Antigens ; Human papillomavirus 16/*immunology ; Humans ; *Immunotherapy ; Interferon-gamma/analysis/*biosynthesis ; Leukocytes, Mononuclear/immunology/metabolism ; T-Lymphocytes, Cytotoxic/immunology/metabolism ; Uterine Cervical Neoplasms/*therapy

OBJECTIVETo find and identify HLA-A*0201 restricted cytotoxic T lymphocyte (CTL) epitopes from epidermal growth factor pathway substrate number 8 (Eps8) for specific immunotherapy based on Eps8-derived epitopes in clinic.

METHODSOnline biological softwares involved C-proteasomal cleavage, MHC class I binding affinity and TAP transport efficiency were used for prediction of HLA-A*0201 restricted epitopes from Eps8. Then, T2-binding assays and peptide/MHC complex stability tests were used to further verify the predicted epitopes. Specific secretion of IFN-γ from human CTL was assayed using the IFN-γ ELISPOT kit, and cytolytic activity was measured by a 4-h lactate dehydrogenase (LDH) release assay. Finally, the functional effects in vivo were measured in HLA-A*0201/Kb transgenic (Tg) mice.

RESULTSFour natural epitopes were designed through online biological softwares. Of the four epitopes selected, p360-368 was found to have the high binding affinity to HLA-A*0201, while p101-109 and p276-284 showed moderate affinities. DC50 of peptide/MHC complexes of the natural epitopes mentioned were all longer than 8 h. In functional assays with human PBMNC in vitro and in HLA-A*0201/Kb transgenic mice in vivo, CTLs primed by each epitope (p101-109, p276-284 and p360-368) secreted IFN-γ and were toxic to cancer cells from a variety of tissue types in an HLA-A*0201-restricted and Eps8-specific manner.

CONCLUSIONNatural epitopes (p101-109, p276-284 and p360-368) may be the HLA-A*0201 restricted epitope derived from Eps8.

Adaptor Proteins, Signal Transducing ; immunology ; Animals ; Epitopes, T-Lymphocyte ; metabolism ; HLA-A2 Antigen ; metabolism ; Humans ; Mice ; Mice, Transgenic ; T-Lymphocytes, Cytotoxic

In allogeneic transplantation, including the B6 anti-BALB.B settings, H60 and H4 are two representative dominant minor histocompatibility antigens that induce strong CD8 T-cell responses. With different distribution patterns, H60 expression is restricted to hematopoietic cells, whereas H4 is ubiquitously expressed. H60-specific CD8 T-cell response has been known to be dominant in most cases of B6 anti-BALB.B allo-responses, except in the case of skin transplantation. To understand the mechanism underlying the subdominance of H60 during allogeneic skin transplantation, we investigated the dynamics of the H60-specific CD8 T cells in B6 mice transplanted with allogeneic BALB.B tail skin. Unexpectedly, longitudinal bioluminescence imaging and flow cytometric analyses revealed that H60-specific CD8 T cells were not always subdominant to H4-specific cells but instead showed a brief dominance before the H4 response became predominant. H60-specific CD8 T cells could expand in the draining lymph node and migrate to the BALB.B allografts, indicating their active participation in the anti-BALB.B allo-response. Enhancing the frequencies of H60-reactive CD8 T cells prior to skin transplantation reversed the immune hierarchy between H60 and H4. Additionally, H60 became predominant when antigen presentation was limited to the direct pathway. However, when antigen presentation was restricted to the indirect pathway, the expansion of H60-specific CD8 T cells was limited, whereas H4-specific CD8 T cells expanded significantly, suggesting that the temporary immunodominance and eventual subdominance of H60 could be due to their reliance on the direct antigen presentation pathway. These results enhance our understanding of the immunodominance phenomenon following allogeneic tissue transplantation.
Animals ; Antigen Presentation ; Antigen-Presenting Cells/immunology/metabolism ; CD8-Positive T-Lymphocytes/*immunology ; Epitopes, T-Lymphocyte/*immunology ; Female ; Graft Rejection/*immunology ; Interferon-gamma ; Lymphocyte Activation/immunology ; Lymphocyte Count ; Mice ; Minor Histocompatibility Antigens/*immunology/metabolism ; *Skin Transplantation ; Transplantation, Homologous

Antibodies, Monoclonal ; chemistry ; immunology ; Antigens, Viral ; chemistry ; genetics ; immunology ; Binding Sites ; Capsid Proteins ; chemistry ; genetics ; immunology ; Epitopes ; chemistry ; genetics ; immunology ; Escherichia coli ; genetics ; metabolism ; Gene Expression ; Hepatitis E ; immunology ; prevention & control ; virology ; Hepatitis E virus ; chemistry ; immunology ; Humans ; Molecular Docking Simulation ; Mutagenesis, Site-Directed ; Peptide Mapping ; Protein Binding ; Recombinant Proteins ; chemistry ; genetics ; immunology ; Viral Hepatitis Vaccines ; administration & dosage ; biosynthesis

Cytotoxic T cells (CTLs) play a key role in the control of Hepatitis B virus (HBV) infection and viral clearance. However, most of identified CTL epitopes are derived from HBV of genotypes A and D, and few have been defined in virus of genotypes B and C which are more prevalent in Asia. As HBV core protein (HBc) is the most conservative and immunogenic component, in this study we used an overlapping 9-mer peptide pool covering HBc to screen and identify specific CTL epitopes. An unconventional HLA-A2-restricted epitope HBc141-149 was discovered and structurally characterized by crystallization analysis. The immunogenicity and anti-HBV activity were further determined in HBV and HLA-A2 transgenic mice. Finally, we show that mutations in HBc141-149 epitope are associated with viral parameters and disease progression in HBV infected patients. Our data therefore provide insights into the structure characteristics of this unconventional epitope binding to MHC-I molecules, as well as epitope specific CTL activity that orchestrate T cell response and immune evasion in HBV infected patients.
Adult ; Amino Acid Sequence ; Animals ; Binding Sites ; Epitopes ; chemistry ; immunology ; metabolism ; Female ; Genotype ; HEK293 Cells ; HLA-A2 Antigen ; metabolism ; Hepatitis B Core Antigens ; chemistry ; immunology ; metabolism ; Hepatitis B virus ; genetics ; metabolism ; Humans ; Hydrogen Bonding ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Transgenic ; Middle Aged ; Molecular Dynamics Simulation ; Mutation ; Protein Binding ; Protein Structure, Tertiary ; T-Lymphocytes, Cytotoxic ; immunology ; metabolism

The aim of this study is to construct a SARS-CoV S protein-specific phage displayed antigen library for the epitope characterization of anti-S monoclonal antibodies (mAbs). First, the full-length gene of SARS-S protein was PCR amplified, purified and then digested with DNase I to obtain DNA fragments in the size range of 50-500 bp. The resulting fragments were blunt-end ligated to the modified phage display vector pComb3XSS. The reactions were electrotransformed into XL1-Blue and infected with VCSM13 helper phage. The SARS-CoV S protein-specific phage displayed antigen library was biopanned and screened against two anti-S mAbs, S-M1 and S-M2. The results showed that we successfully constructed the phage displayed antigen library with a size of 5.7 x 10(6). After three-rounds of biopanning, 14 positive phage clones for S-M1 and 15 for S-M2 were respectively identified. Sequence analyses revealed the possible epitopes of two mAbs. Therefore, the S protein-specific phage displayed antigen library provides a crucial platform for the epitope characterization of anti-S antibodies and it is highly valuable for development of SARS vaccines and diagnostics.
Antibodies, Viral ; immunology ; Bacteriophages ; genetics ; metabolism ; Epitopes ; genetics ; immunology ; Humans ; Membrane Glycoproteins ; genetics ; immunology ; Peptide Library ; SARS Virus ; genetics ; immunology ; Severe Acute Respiratory Syndrome ; immunology ; virology ; Spike Glycoprotein, Coronavirus ; Viral Envelope Proteins ; genetics ; immunology

OBJECTIVETo construct a prokaryotic expression vector of human tau multiepitope peptide for examining the immunogenicity of a TauP1/P2 DNA vaccine in mice using the expressed product.

METHODSThe coding sequence of Tau multiepitope peptide gene was amplified from the plasmid pVAX1-Tau by PCR and inserted into the prokaryotic expression vector pGEX-4T-2 to construct the recombinant plasmid pGEX-4T-2-TauP1/P2. The positive recombinants were transformed into E.coli BL21 cells, and the expression of fusion protein GST-TauP1/P2 was induced by IPTG and identified by SDS-PAGE. Mice was immunized with TauP1/P2 DNA vaccine and the production of the specific antibodies was detected by Dot-blot analysis using the purified fusion protein.

RESULTSA gene fragment 300 bp in length was amplified. Enzyme digestion and DNA sequencing verified correct construction of the prokaryotic expression plasmid pGEX-4T-2-TauP1/P2. The expression of target fusion protein GST-TauP1/P2 was detected by SDS-PAGE. Specific antibodies against TauP1/P2 were detected in the serum of mice immunized with the DNA vaccine using GST-TauP1/P2 fusion protein.

CONCLUSIONThe constructed prokaryotic expression plasmid of human Tau multiepitope peptide is capable of expressing the target fusion protein, which specifically recognizes the specific antibodies against TauP1/P2 in mice immunized with TauP1/P2 DNA vaccine.

Animals ; Epitopes ; immunology ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Humans ; Mice ; Mice, Inbred C57BL ; Peptides ; genetics ; metabolism ; Recombinant Proteins ; biosynthesis ; genetics ; immunology ; Vaccines, DNA ; biosynthesis ; immunology ; tau Proteins ; biosynthesis ; genetics ; immunology

OBJECTIVETo observe the effect of the antibody TSP-2 against a single epitope of mouse Toll-like receptor 2 extracellular domain (mTLR2ECD) on the expression of nuclear factor-kappa B (NF-κB) and cytokines in the intestinal tissue of septic mice.

METHODSMale BALB/c mice were randomly divided into 4 groups, namely the sham-operated group, model group, TSP-2 treatment group and rabbit IgG treatment group. Sepsis was induced by cecal ligation and puncture (CLP), and at 6, 12 or 24 h after the operation, the ileal tissues were harvested from the mice for HE staining. NF-κB expression was detected with immunohistochemistry. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) mRNA expressions were detected with qRT-PCR and their protein expressions by ELISA.

RESULTSThe NF-κB expression in the intestinal tissue significantly increased in the model group as compared with that in the sham- operated group, and decreased after TSP-2 treatment. The model group also showed significantly increased expression levels of TNF-α and IL-6 mRNA and protein in the intestinal tissue (P<0.05), which were lowered by TSP-2 (P<0.05) but not by rabbit IgG treatment (P>0.05).

CONCLUSIONThe TSP-2 antibody can protect the intestine and delay the development of sepsis by inhibiting NF-κB activation and down-regulating TNF-α and IL-6 expressions in mice.

Animals ; Antibodies ; pharmacology ; Immunodominant Epitopes ; immunology ; Interleukin-6 ; genetics ; metabolism ; Intestinal Mucosa ; metabolism ; Male ; Mice ; Mice, Inbred BALB C ; NF-kappa B ; genetics ; metabolism ; Random Allocation ; Receptors, Cell Surface ; immunology ; Sepsis ; metabolism ; Thrombospondins ; immunology ; Toll-Like Receptor 2 ; immunology ; Tumor Necrosis Factor-alpha ; genetics ; metabolism