Fig. 2

Screening the nanobodies against the NDV-NP protein. a Titres of antibodies against NDV-NP protein in the sera from the camel after the fifth immunisation. b Alignment of amino acid sequence of 9 screened nanobodies. Numbering and CDRs are according to the previous methods [4]. The residues at positions 37, 44, 45, and 47 are indicated by red arrows. c Specific reactions between the 9 screened nanobodies and NDV-NP protein. d Titration of the 9 screened nanobodies binding with the NDV-NP protein. e Analysis of the 9 screened nanobodies blocking the binding between the chicken sera and NDV-NP protein by blocking ELISA