Immunogenicity of experimental DNA vaccines encoding hemagglutinin and hemagglutinin stalk of influenza A (H5N8) virus

   Avian influenza A virus subtype H5 is widespread in the bird population, and there is a risk of its transmission to humans, therefore, it is necessary to develop an effective vaccine to prevent virus spread.

   The aim of the work was to develop prototypes of DNA vaccines encoding modified variants of the hemagglutinin trimer of highly pathogenic avian influenza A virus (H5N8) and its fragment (stem) and to study their immunogenic properties.

   Material and methods. DNA constructs were designed, produced and purified, their expression was analyzed in eukaryotic cells using reverse transcription PCR and Western blot analysis. Laboratory animals (Syrian hamsters) were immunized with experimental DNA vaccines using the jet injection method, the antibody titer in their sera was determined using ELISA. The sera were also tested in the virus neutralization reaction in MDCK cell culture.

   Results and discussion. Expression of target genes in experimental DNA vaccines was confirmed at the transcription and translation levels. Immunogenicity analysis showed that immunization of Syrian hamsters with pVAX-H5 and pVAX-H5 delT4 constructs encoding hemagglutinin ectodomain variants with and without the fibritin trimerizing domain of bacteriophage T4 using jet injection resulted in the formation of specific antibodies (average titer 1:3×104 and 1:5×103, respectively) with virus-neutralizing activity (average 50 % neutralizing titer 1:40). At the same time, specific antibodies were not detected in the group of animals immunized with the DNA vaccine encoding the hemagglutinin stalk.

   Conclusions. In the course of the work, DNA vaccines encoding variants of the hemagglutinin trimer of the influenza virus subtype A (H5N8) and its fragment (stem) were designed and obtained. A comparison of the immunogenicity of experimental DNA vaccines was conducted and the most promising variant of the design – pVAX-H5, encoding a modified trimer of the hemagglutinin of the influenza virus with a trimerizing domain of the fibritin of the bacteriophage T4 – was established.

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