The invention discloses a cattle
Brucella recombination strain S19-
delta bp 26-BL and preparation method and application thereof. According to the invention, a cattle
Brucella S19
genome DNA is used as a template, an upstream homologous arm of a bp26
genome is obtained, and a downstream homologous arm of a BLS
gene, a L7 / L12
gene and a bp 26
gene is obtained; the gene fragments are connected in sequence, and a fragment
delta-bp 26-BL is obtained; a pRE112 and the fragment
delta-bp 26-BL are separately subjected to a double
digestion and are connected, and a suicide homologous recombinant
plasmid is obtained; the
plasmid is introduced into a
competent cell of a S19-delta bp 26
bacterial strain, in the selection pressure of
chloramphenicol, and a homologous recombinant single recon is obtained, and then the homologous recombinant single recon is coated on a selection medium for culture, and the cattle
Brucella recombination strain S19-delta bp 26-BL is obtained. The strain has the advantages of good
heredity stability, growth characteristic and appropriate
virulence, and can be used as a mark
vaccine strain for clinic.