[A genetic and molecular biological study of the pathogenicity factors in Brucella]

The use of gene engineering techniques made it possible to obtain strain GSE830, capable of a higher level of expression of the gene of 38-kD protein in immunoblotting with sheep and rabbit antibrucellar sera in comparison with the expression of this gene of other Escherichia coli strains, containing recombinant plasmids with this gene. Due to the presence of the gene of 38-kD protein, recombinant E.coli strains were capable of survival in macrophage-like cell line U937 3.6-6.3 times more effectively. The model of interaction of Brucella pathogenic and nonpathogenic species with HeLa cells was studied. The bank of insertion mutants of B.suis virulent strain 1330 was studied with the use of transposon TnblaM. Out of 380 insertion mutants, 7 clones expressing beta-lactamase and having decreased capacity for multiplication in HeLa cells 48 hours after inoculation were selected. Detailed analysis revealed that 3 of them had lower adhesive capacity, 1 of them had lower invasive capacity and 3 other mutants were less capable of intracellular multiplication in HeLa cells than the initial B.suis strain 1330. All these 7 mutants had different sites of TnblaM insertion into the chromosome of B.suis strain 1330.