Adenovirus belongs to the family of Adenoviridae. As a vaccine carrier, it has high safety and stimulates the body to produce cellular immunity and humoral immunity. This study prepared an adenoviral vector-specific single-domain antibody for use in adenovirus identification and purification. We successfully constructed a single domain antibody phage display library with a capacity of 1.8 × 10⁹ by immunizing and cloning the VHH gene from Bactrian camel. After the second round of biopanning, clones specific for adenovirus were screened using phage ELISA. Twenty-two positive clones were obtained, and two clones with the highest binding affinity from ELISA were selected and named sdAb 5 and sdAb 31 for further application. The recombinant single-domain antibody was solublely expressed in E. coli and specifically bound to adenoviruses rAd26, ChAd63 and HAd5 in ELISA and live cell immunofluorescence assays. We established an effective method for immunoaffinity purification of adenovirus by immobilizing the single domain antibody to Sepharose beads, and it may be used to selectively capture adenoviruses from cell culture medium. The preparation of the adenovirus-specific single-domain antibody lays a foundation for the one-step immunoaffinity purification and identification of adenoviruses.

Background This article aims to study the changes of CTX-II and C2C biomarker concentrations during the pathogenesis of osteoarthritis with SD rats as the research object. Through the longitudinal and joint detection of the content of CTX-II and C2C markers in the serum of anterior cruciate ligament resection (ACLT) rats, the evaluation and early diagnosis of OA disease can be realized, and the theoretical basis for the rapid diagnosis technology of OA can be provided. Methods SD rats were randomly divided into two groups: Sham operation group and OA model group. The OA model was established by anterior cruciate ligament excision (ACLT) for 2, 4, 6, 8, and 10 weeks, respectively. The cartilage gross score and Mankin score were used to evaluate the model. The tibia of the right hind limb was sampled for pathological histology and HE staining. The collected blood samples are used to detect changes in the concentration of CTX-II and C2C in serum. The receiver operating characteristic curve (ROC) was used to compare the area under the curve (AUC) of CTX-II, C2C and combined biomarkers. Results In the model group, the content of CTX-II and C2C in SD rat serum increased significantly, and the content of CTX-II and C2C increased with the prolonged modeling time, which was time dependent; The levels of CTX-II and C2C in the serum of rats in the sham operation group did not change significantly; both macroscopic observations and Mankin scores increased significantly. The AUC of the combined biomarker is higher than that of CTX-II and C2C. Finally, CTX-II and C2C levels were positively correlated with Mankin score. Conclusion Early combined detection of serum CTX-II and C2C concentrations has potential value for the evaluation and diagnosis of osteoarthritis.