The invention discloses a nanobody capable of resisting H9N2 subtype avian influenza viruses, a preparation method and an application. The
amino acid sequence of the nanobody is as shown in SEQID NO:1. The nucleocapsid
protein of the H9N2 subtype avian influenza viruses is expressed through a
prokaryotic expression technique, then the nucleocapsid
protein is used as an
immunogen for immunizing Bactrian camels, a phage
library is constructed, then a nanobody capable of resisting H9N2 nucleocapsid
protein is obtained through screening by a
phage display technique, then the nanobody and
horse radish peroxidase (HRP) are subjected to fusion expression, and a
fusion protein of the nanobody and the HRP is successfully prepared. When the
fusion protein is applied to detection of antibodies capable of resisting H9N2 subtype avian influenza viruses (AIV) in
chicken serum, the inventor finds that a detection method constructed through the
fusion protein is high in sensitivity, and has the advantages that the operation is simple, secondary antibodies do not need to be used, and time consumed for detecting samples is short.