FIELD: biotechnology, molecular biology, genetic engineering. SUBSTANCE: for preparing protein C of alpha-antigen of Streptococcus group B or its functional derivative recombinant DNA molecule is used. This DNA encodes an antigen taken among the group: N, C, N-C, Rx, N-Rx, Rx-C, N- Rx-C and N-R9-C where N means 5'-flanking amino acid sequence and in Rx x means a whole number and represents number of repeating copies of sequence consisting of 82 amino acids; R9 means amino acid sequence consisting of the combination of sequence R9 with additionally partially repeating sequence. Functional derivative of antigen is taken among the group: N, C, R1,R2,R3,R4,R5,R6,R7,R8,R9,R9 and Rx or N-C, N-R1 before N-Rx, or R1-C before Rx-C, or N-R1-C before N- -R9-C and derivative comprises at least 10 repeating R-units. Recombinant DNA is able to express protein, its fragment or its derivative in bacterial cells being DNA nucleotide sequence can be linked with promoter operatively. Plasmid vector is used for expression of protein in cells. The use of invention allows preparing vaccine able to confer in patient immunity against infection causing by Streptococcus group B. Invention can be used for preparing conjugated vaccine able to produce immunity against infection of Streptococcus group B. EFFECT: improved preparing method of vaccine, valuable medicinal properties. 9 cl, 13 dwg
