The invention discloses two types of ScFv (
Single Chain Variable Fragment) antibodies, encoding genes of the antibodies and applications of the antibodies for preparing the preparations for treating or preventing
infectious bursal disease of chicken. Two single-chain antibodies (namely, the
ScFv antibodies) are provided; and the
ScFv antibodies can be specially bound with the
protein 2 (VP2) (
Virus Protein 2) in an IBDV (
Infectious Bursal Disease Virus) structure and a plurality of IBDV strains to block the
cytopathic effect (CPE) of the chicken
embryo fibroblast by the IBDV so as to protect the
young chicken infected with IBDV. The immune serum and egg
yolk antibody are tedious in preparation, high in production cost, unstable in effect, difficult to control industrialized
production quality, capable of causing horizontal
disease spread and the like in a use process; the
ScFv antibodies disclosed by the invention can overcome the above disadvantages and have the advantages of strong specificity, good
treatment effect, controllable industrialized
production quality, capability of preventing the horizontal
disease spread caused by the egg
yolk antibody and the like; and therefore, by virtue of the ScFv antibodies, a new situation is opened up in the IBDV prevention and treatment history, and even in the entire prevention and treatment history for
animal virus diseases.