Fig. 2

Construction and identification of a phage display VHH library. A The VHH genes (approximately 400 bp) were amplified via PCR using the total RNA extracted from the PBMCs as a template. M, DNA Marker 2000; 1–10, different RNA extracted from the PBMC samples. B Evaluation of the correct insertion rate of VHH genes into the pMECS vector via PCR. M, DNA Marker 2000; 1–24, different clones. C The VHH library presented a distinct VHH sequence and good diversity. The residues at positions 37, 44, 45 and 47 are indicated by red arrows, and hydrophilic amino acids are features of nanobodies