Identification of a target polypeptide of the CD169 receptor of bovine macrophage using a phage display peptide...

CD169, a salivary acid adhesion receptor on macrophages, plays a crucial role in enhancing the phagocytic response to pathogenic bacteria and in antibacterial immunity. To explore its potential in targeted veterinary drug applications, we used phage display technology to biopan peptide fragments specific to CD169. After several rounds of screening, 45 phage clones were selected for ELISA testing, resulting in 21 high-affinity clones. DNA sequencing revealed that 65 % of the peptides shared a common amino acid sequence (APRL∗∗∗HHH). A 12-amino acid peptide, CD169-T1, was synthesized with rhodamine B labeling at the N-terminal to assess its targeting capability. Flow cytometry and immunofluorescence assays confirmed that CD169-T1 specifically binds to HEK293T cells expressing bovine CD169 and murine macrophages, showing red fluorescence at the cell membrane. Moreover, the fluorescent marker of CD169-T1 was detected in the flow cytometry test results, thus confirming that the CD169-T1 has a significant targeting effect. The CD169-T1 obtained in this study can serve as the targeted part of the immune preparations to prevent and treat a wide variety of pathogenic bacteria, thus significantly facilitating the antigen presentation and increasing the utilization rate and the immune protection effect. Furthermore, this study provides a reference for the targeted research on CD169.