Objective To construct a library of human-derived anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) single-chain variable fragments (scFv) and screen for broad-spectrum neutralizing antibodies to identify candidate molecules for the development of diagnostic and therapeutic agents. Methods Peripheral blood mononuclear cells (PBMCs) were isolated from the peripheral blood of patients who had recovered from novel coronavirus infection. Total RNA was extracted from these PBMCs and reverse transcribed into cDNA, which was used as a template for constructing a human anti-SARS-CoV-2 scFv library. Phage display technology was used to screen for scFv antibodies specific to the SARS-CoV-2 S protein. Full-length IgG antibodies were synthesized through sequence analysis and human IgG expression, and their binding capacity and neutralizing activity against SARS-CoV-2 were evaluated. Results A human-derived scFv antibody library against SARS-CoV-2 with a capacity of 1.56×10⁷ CFU was successfully constructed. Two specific scFv antibodies were screened from this library and expressed as full-length IgG antibodies (IgG-A10 and IgG-G6). IgG-A10 exhibited strong neutralizing activity against both the original SARS-CoV-2 strain (WT) and the XBB subvariant of the Omicron variant. However, the neutralizing activity of this antibody against the JN.1 sub lineage of the Omicron BA.2.86 variant was moderate. Conclusion This study has successfully constructed a human anti-SARS-CoV-2 scFv antibody library from the peripheral blood of recovered patients, and screened and expressed anti-SARS-CoV-2 IgG antibodies with neutralizing activity, laying a foundation for the prevention, diagnosis, and treatment of SARS-CoV-2 infection.
Humans ; Single-Chain Antibodies/genetics* ; SARS-CoV-2/immunology* ; COVID-19/immunology* ; Immunoglobulin G/genetics* ; Antibodies, Viral/genetics* ; Peptide Library ; Spike Glycoprotein, Coronavirus/immunology* ; Antibodies, Neutralizing/immunology* ; Leukocytes, Mononuclear/immunology* ; Broadly Neutralizing Antibodies/immunology*

Objective To screen the anti-CD22-specific nanobodies to provide a basis for immunotherapy agents. Methods The naive phage nanobody library was constructed and its diversity was analyzed. Three rounds of biotinylated streptavidin liquid phase screening were performed by using biotinylated CD22 antigen as the target, and the sequence of nanobodies against CD22 were identified by ELISA and gene sequencing. Results The capacity of the constructed naive phage nanobody library was 3.89×10⁹ CFU/mL, and the insertion of effective fragments was higher than 85%. Based on this library, seven anti-human CD22 nanobodies were screened, and the amino acid sequence comparison results showed that the overall similarity was 70.34%, and all of them were hydrophilic proteins. The results of protein-protein complex docking prediction showed that the mimetic proteins of the five nanobody sequences could be paired and linked to CD22, and the main forces were hydrophobic interaction and hydrogen bonding. Conclusion This study provided a basis for the study of chimeric antigen receptor T cells targeting CD22, successfully constructed the natural phage nanobody library and obtaining five anti-CD22-specific nanobodies.
Camelus/immunology* ; Single-Domain Antibodies/chemistry* ; Peptide Library ; Humans ; Animals ; Sialic Acid Binding Ig-like Lectin 2/genetics* ; Amino Acid Sequence ; Molecular Docking Simulation

Objective To explore the effects of S100 calcium-binding protein A9 (S100A9) gene knockout on the phenotype of systemic lupus erythematosus (SLE) in mice and to clarify the role of S100A9 in the pathogenesis of SLE. Methods Ten female C57BL/6 wild-type and S100A9 knockout (S100A9-KO ) mice were selected, with five wild-type and five S100A9-KO B6 mice receiving imiquimod (IMQ) cream to establish SLE mouse model. The other five wild-type and five S100A9-KO B6 mice were treated as control groups by wiping the skin of the right ear with a cotton swab. After 8 weeks, the mice were sacrificed. The serum was collected from each mouse to detect the levels of anti-double-stranded DNA (dsDNA) antibodies, immunoglobulin G (IgG), B cell activating factor (BAFF), and interleukin 6 (IL-6) using ELISA. The levels of serum creatinine were determined using a sarcosine oxidase method. Urine was collected to measure urinary protein concentration. Kidneys were collected and stained with hematoxylin and eosin (H&E) for evaluating histological changes. Results After IMQ treatment, the length and weight of spleen, levels of serum creatinine, anti-dsDNA antibodies, IgG, BAFF, IL-6, and urinary protein in the IMQ B6 group and IMQ S100A9-KO B6 group were significantly higher than those of the control groups. Lupus-like changes including increased glomerular volume and tubular epithelial swelling were observed in kidneys from the IMQ and IMQ S100A9-KO groups. However, compared with the IMQ B6 group, the IMQ S100A9-KO B6 group exhibited milder levels of serum and urine indicators as well as the lupus-like symptoms. Conclusion IMQ could induce lupus-like symptoms in both wild-type B6 mice and S100A9-KO B6 mice, but the lesions in S100A9 knockout mice are milder. Theses results suggested that S100A9 is involved in and promotes the pathogenesis of SLE.
Animals ; Lupus Erythematosus, Systemic/chemically induced* ; Female ; Calgranulin B/genetics* ; Mice, Knockout ; Mice, Inbred C57BL ; Phenotype ; Mice ; Interleukin-6/blood* ; Disease Models, Animal ; Antibodies, Antinuclear/blood* ; B-Cell Activating Factor/blood* ; Immunoglobulin G/blood* ; Kidney/pathology*

Objective Currently, there is no commercially available quantitative detection kit for the main Felis domestic allergen (Fel d 1) in China. To establish a rapid detection method for Fel d 1, this study aims to prepare monoclonal antibodies against Fel d 1 protein. Methods The codon preference of Escherichia coli was utilized to optimize and synthesize the Fel d 1 gene. The prokaryotic expression plasmid pET-28a-Fel d 1 was constructed and used to express and purify the recombinant Fel d 1 protein. Subsequently, the recombinant protein was immunized into BALB/c mice and monoclonal antibodies (mAbs) were prepared by the hybridoma technique. An indirect ELISA was established using the recombinant Fel d 1 as the coating antigen, and hybridoma cell lines were screened for positive clones. The specificity and antigenic epitopes of the mAbs were confirmed by Western blot analysis. Finally, the selected hybridoma cells were injected into the peritoneal cavities of BALB/c mice for large-scale monoclonal antibody production. Results The recombinant plasmid pET-28a-Fel d 1 was successfully constructed, and soluble Fel d 1 protein was obtained after optimizing the expression conditions. Western blot and antibody titer assays confirmed the successful isolation of two hybridoma cell lines, 7D11 and 5H4, which stably secreted mAbs specific to Fel d 1. Antibody characterization revealed that the 5H4 mAb was of the IgG2a subtype and could recognize the amino acid region 105-163 of Fel d 1, while the 7D11 mAb was the IgG1 subtype and could recognize the amino acid region 1-59. Conclusion The high-purity recombinant Fel d 1 protein produced in this study provides a promising alternative for clinical immunotherapy of cat allergies. Furthermore, the monoclonal antibody prepared in this experiment lays a material foundation for the in-depth study of the biological function of Fel d 1 and the development of ELISA detection.
Animals ; Antibodies, Monoclonal/biosynthesis* ; Mice, Inbred BALB C ; Cats ; Mice ; Allergens/genetics* ; Glycoproteins/genetics* ; Enzyme-Linked Immunosorbent Assay ; Hybridomas/immunology* ; Recombinant Proteins/genetics* ; Female ; Antibody Specificity

Objective To prepare monoclonal antibodies against bovine CD4 and identify their basic biological characteristics. Methods Recombinant bovine CD4 (rHis-BoCD4 and rGST-BoCD4) was successfully expressed and purified by constructing a prokaryotic plasmid of bovine CD4 gene. The bovine CD4 monoclonal antibody was produced using hybridoma technology. The subtype and potency of the monoclonal antibody were identified and analyzed by ELISA, while specificity was analyzed through indirect immunofluorescence assay (IFA) and Western-blot. Results Four hybridoma cell lines, namely, 1H4, 6A10, 3F9 and 4G10, stably secreting monoclonal antibodies against BoCD4 were successfully obtained. The subclasses of the monoclonal antibodies subclass 6A10 was IgG2b and the rest of the monoclonal antibodies were of IgM type. Western-blot results showed that the four anti-bovine CD4 mAb strains were able to specifically bind to the bovine CD4 protein expressed in vitro. Indirect immunofluorescence assay showed that four monoclonal antibodies were able to specifically recognize the natural bovine CD4 protein. Flow cytometry assay showed that 3F9 was best to recognize bovine natural CD4 molecules. Conclusion Four monoclonal antibody strains with high specificity to natural bovine CD4 protein were successfully prepared, which lays the foundation for the subsequent studies on the function of bovine CD4 and diagnosis and treatment of bovine T-lymphocyte diseases.
Animals ; Antibodies, Monoclonal/isolation & purification* ; Cattle ; CD4 Antigens/genetics* ; Hybridomas/immunology* ; Antibody Specificity/immunology* ; Mice ; Mice, Inbred BALB C ; Enzyme-Linked Immunosorbent Assay ; Fluorescent Antibody Technique, Indirect

Objective The study aims to investigate the immunological functions of the nucleocapsid (N) protein of the novel coronavirus Omicron (BA.1, BA.2) and evaluate the differences among different N proteins of mutant strains in immunogenicity. Methods By aligning sequences, the mutation sites of the Omicron (BA.1, BA.2) N protein relative to prototype strain of the novel coronavirus (Wuhan-Hu-1) were determined. The pET-28a-N-Wuhan-Hu-1 plasmid was used as template to construct pET-28a-BA.1/BA.2-N through single point mutation or homologous recombination. The three kinds of N protein were expressed in prokaryotic system, purified through Ni-NTA affinity chromatography, and then immunized into mice. The titer and reactivity of the polyclonal antibody, as well as the expression level of IL-1β and IFN-γ in mouse spleen cells, were detected using indirect ELISA and Western blot assay. Results The constructed prokaryotic expression plasmids were successfully used to express the Wuhan-Hu-1 N, BA.1 N, and BA.2 N proteins in E.coli BL21(DE3) at 37 DegreesCelsius for 4 hours. The indirect ELISA test showed that the titers of polyclonal antibody prepared by three N proteins were all 1:51 200. All three N proteins can increase the expression of IFN-γ and IL-1β cytokines, but the effect of Omicron N protein in activing two cytokines was more obvious than that of Wuhan-Hu-1 N protein. Conclusion The study obtained three new coronavirus N proteins and polyclonal antibodies, and confirmed that mutations in the amino acid sites of the N protein can affect its immunogenicity. This provides a basis for developing rapid diagnostic methods targeting N protein of different novel coronavirus variants.
Animals ; Mice ; SARS-CoV-2/genetics* ; Coronavirus Nucleocapsid Proteins/immunology* ; Nucleocapsid Proteins/isolation & purification* ; COVID-19/immunology* ; Antibodies, Viral/immunology* ; Mice, Inbred BALB C ; Interferon-gamma/metabolism* ; Interleukin-1beta/metabolism* ; Female ; Escherichia coli/metabolism* ; Mutation ; Humans

Objective To prepare CD318-specific monoclonal antibodies and evaluate their specificity, affinity, and application in immunological detection, laying the foundation for the development of CD318-targeted antibody drugs. MethodsCD318 protein was expressed and purified, and was used as an antigen to immunize mice, then mice with higher antiserum titers were screened. We prepared CD318-specific monoclonal antibodies through cell fusion and monoclonal screening, and the specificity, affinity, and application of the obtained monoclonal antibodies in immunological assays were evaluated. Then we constructed a CD318/CD3-targeting bispecific antibody and assessed its impact on T-cell cytotoxicity. Results Thirteen monoclonal antibodies were successfully generated, with the hybridoma clone 13-8-G2 exhibiting the highest titer, strongest specificity, and broadest applicability. The antibody was identified as an IgG1 isotype with a kappa light chain. The variable region of the light chain measured 318 bp, while the heavy chain variable region was 357 bp, yielding an affinity constant of approximately 7.68×10⁹. The specificity of CD318 was confirmed using flow cytometry and immunofluorescence assays. Additionally, a CD318/CD3-targeting bispecific antibody was constructed using the variable regions of this CD318 monoclonal antibody, which demonstrated enhanced T-cell cytotoxicity. Conclusion High-affinity and highly specific CD318 monoclonal antibodies were successfully prepared, laying a foundation for the development of therapeutic antibodies targeting CD318.
Animals ; Antibodies, Monoclonal/biosynthesis* ; Mice ; Antibodies, Bispecific/immunology* ; Humans ; Mice, Inbred BALB C ; Antibody Specificity/immunology* ; CD3 Complex/immunology* ; Antigens, CD/genetics* ; T-Lymphocytes/immunology* ; Hybridomas/immunology* ; Female

Objective Analyze the human leukocyte antigen(HLA) class-I antibody specificity and antigenic determinants in patients with ineffective platelet transfusion, to provide theoretical basis for the establishment and application of platelet donor bank in Shandong Province. Methods 69 patients with ineffective platelet transfusion, the patients specimens were subjected to specific detection of HLA class-I antibody, and the possible antigenic determinants were analyzed using HLA Matchmaker software, and the relative immunogenicity of the antigen was calculated. Results A total of 113 specific antibodies were detected in 69 patient specimens. Among which 33 were antibodies to the HLA-A loci, with the highest frequency of HLA-A*69:01 (54%), 54 were antibodies to the HLA-B loci, and the highest frequency of HLA-B*15:12 (64%); 25 antibodies against Cw loci with low platelet expression were detected, with HLA-C*17:01 having the highest frequency (38%). Using HLA Matchmaker software, a total of 221 HLA class I epitopes were detected, among which 163LG and 163L had the highest probability, reaching 59.4%. Among the HLA-A loci, the allele HLA-A*02:03 has the highest relative immunogenicity at 137.157, while the allele HLA-A*02:05 has the lowest relative immunogenicity at 0.1450. In the HLA-B locus, the relative immunogenicity of HLA-B*73:01 allele is the highest, reaching 229.885, while the relative immunogenicity of HLA-B*13:02 allele is the lowest, reaching 0.121. Conclusion This study obtained the distribution characteristics of HLA class-I antibodies in PTR patients in Shandong population, providing theoretical basis for precise platelet transfusion, improving transfusion efficiency, and establishing and applying platelet supply banks.
Humans ; Platelet Transfusion ; Male ; Female ; Middle Aged ; Epitopes/genetics* ; China ; Adult ; Histocompatibility Antigens Class I/genetics* ; Antibodies/blood* ; Aged ; Young Adult ; HLA-A Antigens/genetics* ; Adolescent ; HLA-B Antigens/genetics*

This study investigated the specific immune response of BALB/c mice that was induced by a circular RNA (circRNA) vaccine expressing the herpes simplex virus type II (HSV-2) glycoprotein D (gD). The aim was to evaluate the immunological potential of this vaccine and lay a foundation for developing an mRNA vaccine against HSV-2. PCR and homologous recombination were employed to integrate the gD gene obtained from the pT7AMP-gD ectodomain plasmid into pUC57 to generate the recombinant plasmid pUC57-circ-gD, which was then sequenced and characterized. In vitro transcription and cyclization were performed on the template DNA to generate pUC57-circ-gD mRNA. To validate the formation of circular RNA, we cleaved the pUC57-circ-gD mRNA with RNase R and employed RT-PCR to validate the cyclization. The pUC57-circ-gD mRNA was then transfected into 293T cells. After 72 h, the cell supernatant was collected, and Western blotting was employed to measure the protein level of gD. Subsequently, the mRNA was encapsulated in lipid nanoparticles (LNPs) by microfluidic encapsulation. BALB/c mice were administrated with the encapsulated mRNA, and blood was collected from the fundus venous plexus after 21 and 35 days, and from the enucleated eyeballs after 49 days. Enzyme-linked immunosorbent assay was employed to measure the titers of antibodies, including virus-neutralizing antibodies. After 49 days, spleens were harvested and assessed for secretion of interferon-gamma (IFN-γ) by solid-phase enzyme-linked immunospot. The results showed successful construction and sequencing of the recombinant plasmid. RNase R digestion confirmed the presence of circular RNAs. Western blotting of the 293T cells transfected with the mRNA showed clear specific bands. The quality of the vaccine was tested by size exclusion chromatography-high performance liquid chromatography, which showed that the purity of the vaccine was about 90%. The mRNA-LNP showcased the particle size of 82.76 nm and an encapsulation rate of approximately 98%. Following three-dose vaccination, all immunized mice exhibited steady weight gain with 100% survival rate throughout the 28-day observation period, indicating no significant acute toxicity associated with the vaccine formulation. The immunized mice showed dose-dependent increases in serum IgG antibody titer and IFN-γ secretion by splenocytes and they were resistant to virus attacks. These findings indicate good immunogenicity and persistence of the pUC57-circ-gD mRNA vaccine, providing a reference for further studies on circRNA vaccines.
Animals ; Mice, Inbred BALB C ; RNA, Circular ; Mice ; Humans ; Herpesvirus 2, Human/genetics* ; Viral Envelope Proteins/genetics* ; Antibodies, Viral/blood* ; HEK293 Cells ; Female ; Nanoparticles ; Plasmids

To prepare antibodies that specifically recognize the conserved domain in the large extracellular loop of the CD63 protein, we expressed anti-CD63 single-chain variable fragment (scFv) antibody in Pichia pastoris in a secreted form. The purified expression product was found to bind specifically with CD63 protein and recognize CD63 on the surface of SK-MEL-28 cells. The variable region of the anti-CD63 monoclonal antibody in an anti-CD63-positive cell line was sequenced. The anti-CD63 scFv consisted of a variable heavy chain and a variable light chain linked by a flexible peptide was then designed. After codon optimization, the gene was synthesized and cloned into the expression plasmid pPICZα-A. The SacI-linearized plasmid was electroporated into P. pastoris X33, and 1% methanol were used to induce the expression of scFv. The fermentation supernatant was purified by Ni column. Anti-CD63 scFv was identified by SDS-PAGE and Western blotting, and its biological activities were analyzed by immunoblotting, immunofluorescence, cell-based ELISA, and flow cytometry. A P. pastoris strain capable of expressing and secreting anti-CD63 scFv was successfully obtained. The antibody had a molecular weight of approximately 30 kDa and specifically recognized CD63 protein. The expression of anti-CD63 scFv in P. pastoris paves the way for the production of anti-CD63 antibodies on a large-scale, which is undoubtedly an economical and effective way of antibody acquisition.
Single-Chain Antibodies/immunology* ; Humans ; Tetraspanin 30/immunology* ; Recombinant Proteins/immunology* ; Pichia/genetics* ; Saccharomycetales/metabolism*