Humanized single-chain antibody 7D of clostridium perfringens alpha-toxin

The invention discloses a humanized single-chain antibody 7D of clostridium perfringens alpha-toxin. The humanized single-chain antibody 7D is screened from a phage antibody library Source bioscience, is a full-humanized antibody of the clostridium perfringens alpha-toxin and can be used for achieving a toxin neutralization treating effect, overcoming various side effects of a heterologous antibody and eliminating complex steps and high cost of humanization modification on the heterologous antibody; and the single-chain antibody is small in molecular weight, strong in in-vivo penetrability and capable of rapidly reaching to damaged tissues and cells to exert an antitoxin effect, so that the double aims of economy and high efficiency are achieved. The alpha-toxin has a certain homology with other types of toxins of clostridium perfringens, so that the antibody drug possibly generates inhibiting and treating effects for other types of toxins and can also be used as a detecting reagent to detect the clostridium perfringens alpha-toxin.