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Background: Antibodies have been proven effective as diagnostic agents for detecting zoonotic diseases. The variable domain of camel heavy chain antibody (VHH), as an antibody derivative, may be used as an alternative for traditional antibodies in existing immunodiagnostic reagents for detecting rapidly spreading infectious diseases. Objectives: To expedite the isolation of specific antibodies for diagnostic purposes, we constructed a semi‐synthetic camel single domain antibody library based on the phage display technique platform (PDT) and verified the validity of this study. Methods: The semi‐synthetic single domain antibody sequences consist of two parts: one is the FR1‐FR3 region amplified by RT‐PCR from healthy camel peripheral blood lymphocytes (PBLs), and the other part is the CDR3‐FR4 region synthesised as an oligonucleotide containing CDR3 randomised region. The two parts were fused by overlapping PCR, resulting in the rearranged variable domain of heavy‐chain antibodies (VHHs). Y. pestis low‐calcium response V protein (LcrV) is an optional biomarker to detect the Y. pestis infection. The semi‐synthetic library herein was screened using recombinant (LcrV) as a target antigen. Results: After four cycles of panning the library, four VHH binders targeting 1–270 aa residues of LcrV were isolated. The four VHH genes with unique sequences were recloned into an expression vector and expressed as VHH‐hFc chimeric antibodies. The purified antibodies were identified and used to develop a lateral flow immunoassay (LFA) test strip using latex microspheres (LM) for the rapid and visual detection of Y. pestis infection. Conclusions: These data demonstrate the great potential of the semi‐synthetic library for use in isolation of antigen‐specific nanobodies and the isolated specific VHHs can be used in antigen‐capture immunoassays. [ABSTRACT FROM AUTHOR]

Neoantigen delivery using extracellular vesicles (EVs) has gained extensive interest in recent years. EVs derived from tumour cells or immune cells have been used to deliver tumour antigens or antitumor stimulation signals. However, potential DNA contamination from the host cell and the cost of large‐scale EV production hinder their therapeutic applications in clinical settings. Here, we develop an antigen delivery platform for cancer vaccines from red blood cell‐derived EVs (RBCEVs) targeting splenic DEC‐205+ dendritic cells (DCs) to boost the antitumor effect. By loading ovalbumin (OVA) protein onto RBCEVs and delivering the protein to DCs, we were able to stimulate and present antigenic OVA peptide onto major histocompatibility complex (MHC) class I, subsequently priming activated antigen‐reactive T cells. Importantly, targeted delivery of OVA using RBCEVs engineered with anti‐DEC‐205 antibody robustly enhanced antigen presentation of DCs and T cell activation. This platform is potentially useful for producing personalised cancer vaccines in clinical settings. [ABSTRACT FROM AUTHOR]

Nanoparticle‐based electrochemical immunosensors are fascinating and promising screening systems that rely on the affinity binding between antibodies and antigens, allowing the specific detection of diverse types of targets (e. g., proteins, hormones, antibodies). The employment of nanoparticles in the realization of such devices dramatically improves the selectivity, sensitivity, and the transducer surface area for effectively immobilizing the bioreceptor or target molecules. During the last years, the nanoparticles design and fabrication was mainly focused on taking advantage from synergistic effects due to the coupling of different materials. In this review, we summarize the very recent advancements in this regard, with specific emphasis to nanoparticle syntheses procedures, antibody oriented immobilization strategies and transduction techniques. Moreover, the last trends and applications have been extensively discussed along with the remaining challenges and future perspectives. [ABSTRACT FROM AUTHOR]