Adeno-associated virus with site-directed mutagenesis and site-directed modification and preparation method and application thereof

A site-specifically mutated adeno-associated virus capsid protein VP1 or a fragment thereof, wherein an amino acid at a specific site of a corresponding wild type adeno-associated virus capsid protein VP1 or a fragment thereof is mutated as an non-natural amino acid, and the specific site is at least one site selected from sites R447, G453, S578, N587, N587+1, S662 of VP1 or fragment thereof;

• wherein the non-natural amino acid is an azido-containing non-natural amino acid, Nε-2-azideoethyloxycarbonyl-L-lysine (NAEK),
• or the non-natural amino acid is an non-natural amino acid with structure DiZPK;
• wherein the NAEK and the amino acid sequence of VP1 or fragment thereof are linked as shown in Formula I:
• wherein the direction from R1 to R2 is the direction from N-terminal to C-terminal of the amino acid sequence, in which amino acid at site N is one of amino acids at sites selected from site R447, site G453, site S578, site N587, site N587+1, site S662, R1 is an amino acid residue at site 1 to site N-1 of the amino acid sequence of VP1 or fragment thereof, R2 is an amino acid residue at site N+1 to C-terminal of the amino acid sequence of VP1 or fragment thereof;
• wherein the DiZPK and the amino acid sequence of VP1 or fragment thereof are linked as shown in Formula II:
• wherein the direction from R1 to R2 is the direction from N-terminal to C-terminal of the amino acid sequence, in which amino acid at site N is one of amino acids at sites selected from site R447, site G453, site S578, site N587, site N587+1, site S662, R1 is an amino acid residue at site 1 to site N-1 of the amino acid sequence of VP1 protein or fragment thereof, R2 is an amino acid residue at site N+1 to C-terminal of the amino acid sequence of VP1 protein or fragment thereof,
• R3 is