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 investigate the improvement effect mechanism of Xibining prescription （XBN） on knee osteoarthritis （KOA） model rats based on AMP-activated protein kinase（AMPK）/mammalian target of rapamycin （mTOR） signaling pathway. METHODS Totally 36 rats were randomly divided into blank group， model group， XBN group （12.56 g/kg）， XBN+metformin （AMPK agonist） group （12.56 g/kg XBN+100 mg/kg metformin）， with 9 rats in each group. Except for blank group， KOA model was induced by anterior cruciate ligament transection in other groups. After modeling， each group was given relevant medicine/normal saline， XBN and normal saline intragastrically， once a day， and metformin intraperitoneally， every other day， for 4 consecutive weeks. The pathomorphological changes of cartilage tissue in rats were observed and Mankin scoring was conducted. The expression level of Aggrecan in rat cartilage， mRNA and protein expressions of platelet reactive protein disintegrin and metalloproteinase with thrombospondin motifs 4 （ADAMTS-4）， ADAMTS-5， matrix metalloproteinase 3 （MMP-3） and MMP- 13， and the phosphorylation level of AMPK and mTOR proteins were detected. RESULTS Compared with blank group， the structure of cartilage tissue in the model group was disordered， the matrix of cartilage layer was lightly stained，the tide line was distorted or interrupted， and Mankin score was significantly increased （P＜0.05）. The protein expression of Aggrecan in cartilage tissue and the phosphorylation level of AMPK protein were all decreased significantly （P＜0.05）； mRNA and protein expressions of ADAMTS-4， ADAMTS-5， MMP-3 and MMP-13 and the phosphorylation levels of mTOR protein were significantly increased in cartilage tissues （P＜0.05）. Compared with model group， the pathological morphology of cartilage was improved significantly in each administration group， and above score or indexes were reversed significantly （P＜0.05）. Compared with XBN group， the degree of cartilage lesions in rats was further alleviated in XBN+ metformin group， and the levels of above score or indicators were further improved （P＜0.05）. CONCLUSIONS XBN can ameliorate cartilage injury in KOA model rats， promote cartilage synthesis and reduce cartilage degradation， the mechanism of which may be associated with activating AMPK/mTOR signaling pathway.