The major concern for severe acute respiratory syndrome (SARS), caused by the SARS-associated coronavirus (SARS-CoV), is the lack of diagnostic and therapeutic agents. Using a phage display technology in a chicken system, high-affinity monoclonal antibody fragments against the SARS-CoV spike protein were characterized. Ten truncated spike protein gene fragments were expressed in Escherichia coli cells. Following the immunization of chickens with these recombinant spike proteins, two single-chain variable fragment (scFv) antibody libraries were established with short or long linkers to contain 5 × 10 7 and 9 × 10 6 transformants, respectively. After four rounds of panning selection, the scFv antibodies of randomly chosen clones were demonstrated by Coomassie blue staining, and verified by western blot analysis. In a comparison of nucleotide sequences with the chicken germline gene, we found that all clones varied in the complementarity-determining regions, that two scFv antibodies reacted significantly with SARS-CoV-infected Vero cells, and that those two specific scFv antibodies recognized the same region of the spike protein spanning amino acid residues 750-1000. In conclusion, the results suggest that the chicken scFv phage display system can be a potential model for mass production of high-affinity antibodies against the SARS-CoV spike protein.
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Lee, Y. C., Leu, S. J. C., Hu, C. J., Shih, N. Y., Huang, I. J., Wu, H. H., Hsieh, W. S., Chiang, B. L., Chiu, W. T., & Yang, Y. Y. (2007). Chicken single-chain variable fragments against the SARS-CoV spike protein. Journal of Virological Methods, 146(1-2), 104-111. https://doi.org/10.1016/j.jviromet.2007.06.010