Fig. 1

Construction of the immunized VHH library. a: Assessment of camel immunization by evaluating the presence of CD19-reactive antibodies in the serum of the animal using ELISA. The control consists of the animal’s serum before immunization with the CD19-positive cell lines. The values are presented as the mean of at least three replicates. b: Gel electrophoresis results of the first round of PCR for library construction. Lane M: DNA marker, Lane 1, 2, 3, and 4: PCR amplicons corresponding to approximately 700 bp. c: Gel electrophoresis results of the second round of PCR for library construction. Lane 1, 2, 3, 4, 5, 6, and 7: PCR amplicons corresponding to approximately 400 bp to 500 bp, Lane M: DNA marker. d: Restriction digestion of the VHH-encoding DNA fragments by SfiI. Lane 1: The SfiI-digested VHH-encoding DNA fragments, Lane M: DNA marker. e: Restriction digestion of the pComb3xSS phagemid by SfiI. The SfiI-digested pComb3xSS phagemid vector corresponding to approximately 3300 bp was later on extracted from the gel and used for the ligation process. Lane 1: SfiI-digested pComb3xSS phagemid, Lane M: DNA marker