FIELD: chemistry.;SUBSTANCE: invention relates to recombinant plasmid pVA891-2[mutR], a method of producing mutR gene-mutant strains of Streptococcus pyogenes and recombinant strains of Streptococcus pyogenes. The plasmid pVA891-2[mutR] is constructed based on the vector pVA891-2 which is incapable of replicating in cells of gram-positive microorganisms and contains an erythromycin resistance marker gene, by introducing a Pstl-Sacl fragment of the mutR gene of the Streptococcus pyogenes SF370 strain with size of 520 bps, shown on fig.1. To obtain mutant avirulent strains of Streptococcus pyogenes (SF3 70[mutR], No.97[mutR], No.152[mutR), the obtained plasmid is introduced into corresponding strains of S. pyogenes, which results in violation of the structural region of the mutR gene in the genome of such strains. Selection of clones with an inactivated mutR gene enabled to obtain strains in which exhibition of virulent properties is absent or considerably reduced.;EFFECT: group of inventions can be used in preventive medicine when producing vaccines.;5 cl, 8 dwg
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