[Preparation and characterization of chicken anti-human B7-H4 IgY polyclonal antibody]

Objective To prepare anti-human B7 homolog 4 (B7-H4) egg yolk immunoglobulins (IgY) polyclonal antibody and establish a double-antibody sandwich ELISA for the detection of soluble B7-H4 (sB7-H4) protein in human serum. Methods Bioinformatics was used to screen specific B cell epitope peptides of human sB7-H4. New Hyland Grey laying hens were immunized with these peptides, and the eggs from the immunized hens were collected to purify chicken anti-human B7-H4 IgY antibody. The purity, concentration and titer of the antibody were detected, and its specificity and function of the antibodies were verified by using ELISA, Western blot analysis and flow cytometry, respectively. A double-antibody sandwich ELISA was established to detect sB7-H4 in clinical samples by using the IgY antibody. Comparative detection was performed using a commercialized ELISA kit on the same set of clinical samples. Results The chicken anti-human B7-H4 IgY antibodies were successfully prepared and proven to be highly specific for the human B7-H4 protein. The ELISA established with the IgY polyclonal antibody detected significantly higher levels of soluble B7-H4 in the serum of patients with ovarian cancer and benign ovarian tumors compared to healthy controls. These results were consistent with the detection results obtained using a commercialized ELISA kit. However, the ELISA with IgY antibody exhibited higher sensitivity than the commercialized kit. Conclusion The chicken polyclonal antibody against human B7-H4 IgY is successfully prepared, and a double-antibody sandwich ELISA suitable for detecting sB7-H4 protein in human serum is established.