Method for creating a recombinant strain of enterococcus L3-SARS based on biologically active strain Enterococcus faecium L3

The current pandemic caused by the SARS-Cov-2 virus has significantly influenced the emergence of new injectable vaccines that provide a predominantly specific IgG response. However, it is generally accepted that protection against pathogens at the mucosal surface, which is the first barrier to viral entry, is predominantly dependent on the IgA response. It is now widely accepted that the use of genetically modified microorganisms, including probiotics, allows the oral or nasal mucosal delivery of therapeutic molecules, inducing an immune response in the mucous membranes. Probiotic strains are well studied for safety for the organism and are able to remain viable after passing through the gastric barrier, improve intraepithelial connections, and can generate a number of surface expressed molecules that enhance the effectiveness of vaccination.

Recombinant probiotic microorganisms capable of producing vaccine antigens by inserting specific DNA fragments into their genome are one of the potential platforms that can be used to develop an appropriate vaccine containing a specific antigen for rapid response to viral mutations. Here, we demonstrate the construction of a novel SARS-Cov-2 vaccine candidate employing the gene fragment of S1 SARS-Cov-2 gene. According to the available data on new variants of SARS-Cov-2 mutations, three amino acid substitutions were made in the chosen sequence. This DNA fragment was inserted in frame into major pili protein gene within d2 domain of enterococcal operon encoding for pili.

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