Abstract
When testing anti-brucellosis vaccines, an important role is played by studying the infecting dose of control strains. To restore the virulent properties of the control strains Brucella melitensis 16 M and Brucella abortus 544, it is necessary to carry out multiple successive passages in different doses (starting from 1,000,000 colony-forming units, CFU/cm3 to 5 CFU/cm3), through the body of sensitive laboratory animals. In this case, for experimental work, we took 54 heads of guinea pigs (males) weighing 350-380 g, from which we created 9 groups of 6 heads each. The article reflects the progress and results of research into determining the minimum fixing infectious dose of the control reference strains Brucella melitensis 16 M and Brucella abortus 544.Based on the results of the studies, the minimum infectious dose (5 CFU) of Brucella after the ninth passage, which causes the generalized form of brucellosis, was determined. Spent virulent fixing doses (5 CFU/cm3) strains of Brucella melitensis 16 M and Brucella abortus 544 can be used for control infection when setting up various experiments to determine and evaluate the immunogenicity of anti-brucellosis vaccines and chemoprophylaxis.