PLASMID WITHOUT RESISTANCE TO ANTIBIOTIC Russian patent published in 2015 - IPC C12N15/63 C12N15/64 

FIELD: medicine.

SUBSTANCE: claimed invention relates to biotechnology and represents an expression plasmid without resistance to an antibiotic, containing a polynucleotide, coding a repressor protein cI. The expression of the said repressor protein regulates the expression of a toxic gene product, embedded into a non-essential section of a host genome. The claimed invention also discloses a constructed host cell, belonging to Gram-negative bacteria, which contains the said plasmid. The host cell is used to obtain the plasmid or to obtain a protein or an immunogen, if the expression plasmid additionally contains genes, coding the said protein or immunogen. The method of obtaining the expression plasmid and the method of obtaining the protein or immunogen are carried out in several stages. First, a strain of host cells, belonging to the Gram-negative bacteria, is created by embedding by the allele substitution of the gene, coding the toxic product, into the non-essential section of a host chromosome. After that, construction of the DNA-plasmid, which contains the gene, coding the repressor protein cI, and in case of necessity the gene, coding the protein or immunogen, is performed. Then, the obtained host cells are transformed by the said plasmid and grown in the presence of sucrose at a temperature of 30-42°C.

EFFECT: invention makes it possible to realise control of the toxic gene, localised on a chromosome, by means of the repressor, localised on the plasmid in the absence of selective pressure by an antibiotic.

33 cl, 31 dwg, 8 tbl, 10 ex