Construction and application of avibacterium paragallinarum gene deletion and screening system

The invention belongs to the technical field of biology, and discloses a construction method of an avibacterium paragallinarum gene deletion and screening system, which specifically comprises the following steps: step 10, introducing plasmid pSJ001 into avibacterium paragallinarum, and screening through antibiotics corresponding to resistance genes to obtain a first homologous recombination strain; step 20, introducing the plasmid pSJ002 into the primary recombinant strain, and screening through a blue-white spot screening system to obtain a secondary homologous recombinant strain; after the method is applied to strain screening, target strains containing lacZ genes and resistance genes are screened by using corresponding antibiotics through forward screening, and screening is performed by using an X-Gal blue-white system through reverse screening. After the two methods are combined, the avibacterium paragallinarum gene deletion mutant strain can be visually, simply, conveniently and efficiently screened out.