Mutant strain of Brucella bacterin with weak poison, constructing method, and application

This invention discloses attenuated Brucella mutant, its construction method and its application. The attenuated Brucella mutant is constructed by deleting bp26, wboA, omp31, and P39 or pgm gene from attenuated Brucella. It is proven by experiments that attenuated Brucella mutant has good immune protection effects and the same virulence as attenuated Brucella. Because certain antigen is delected in the attenuated Brucella mutant, vaccine immunity and natural infection can be differentiated according to the immunobiology of the deleted gene. The attenuated Brucella mutant can be used to manufacture preventative Brucella vaccine and marked attenuated vaccine, and prevent epidemic diseases caused by Brucella.