[Virus-like particles--a new strategy for production of vaccines against influenza virus].

Numerous studies demonstrated that simultaneous expression of some viral proteins in the cell with the aid of a process of self-assembly might lead to the formation of the virus-like particles (VLP) even in the absence of the viral genome. The morphological and antigenic similarity between VLP and native virions represents a promising approach to the new type of vaccines. In the last decade, the threat of the influenza strains with pandemic potential becomes more important. Therefore, the technology for obtaining a new generation of safe and effective non-embryo culture vaccines was developed on the basis of the influenza VLP produced in various expression systems. This provides great advantages in comparison with existing methods of vaccine production. Such vaccines induced full humoral and cellular immune response in animals and humans. This review is focused on the literature concerning the influenza VLPs obtained in various expression systems including insect, mammalian and plant cells.

Plant-produced recombinant influenza vaccine based on virus-like HBc particles carrying an extracellular domain of M2 protein.

Conventional influenza vaccines are based on a virus obtained in chicken embryos or its components. The high variability of the surface proteins of influenza virus, hemagglutinin and neuraminidase, requires strain-specific vaccines matching the antigenic specificity of newly emerging virus strains to be developed. A recombinant vaccine based on a highly conservative influenza virus protein M2 fused to a nanosized carrier particle can be an attractive alternative to traditional vaccines. We have constructed a recombinant viral vector based on potato X virus that provides for expression in the Nicotiana benthamiana plants of a hybrid protein M2eHBc consisting of an extracellular domain of influenza virus M2 protein (M2e) fused to hepatitis B core antigen (HBc). This vector was introduced into plant cells by infiltrating leaves with agrobacteria carrying the viral vector. The hybrid protein M2eHBc was synthesized in the infected N. benthamiana plants in an amount reaching 1-2% of the total soluble protein and formed virus-like particles with the M2e peptide presented on the surface. Methods of isolation and purification of M2eHBc particles from plant producers were elaborated. Experiments on mice have shown a high immunogenicity of the plant-produced M2eHBc particles and their protective effect against lethal influenza challenge. The developed transient expression system can be used for production of M2e-based candidate influenza vaccine in plants.

Recombinant influenza vaccines.

This review covers the problems encountered in the construction and production of new recombinant influenza vaccines. New approaches to the development of influenza vaccines are investigated; they include reverse genetics methods, production of virus-like particles, and DNA- and viral vector-based vaccines. Such approaches as the delivery of foreign genes by DNA- and viral vector-based vaccines can preserve the native structure of antigens. Adenoviral vectors are a promising gene-delivery platform for a variety of genetic vaccines. Adenoviruses can efficiently penetrate the human organism through mucosal epithelium, thus providing long-term antigen persistence and induction of the innate immune response. This review provides an overview of the practicability of the production of new recombinant influenza cross-protective vaccines on the basis of adenoviral vectors expressing hemagglutinin genes of different influenza strains.

Development of Recombinant Vaccine against A(H1N1) 2009 Influenza Based on Virus-like Nanoparticles Carrying the Extracellular Domain of M2 Protein.

The conventional vaccines currently being used to deal with influenza are based on a virus obtained in chicken embryos or its components. The high variability of the major immunogenic surface proteins - hemagglutinin and neuraminidase-require the development of strain-specific vaccines that match the antigenic specificity of a newly emerging virus. Recombinant vaccines based on single viral proteins that could be easily produced in standard expression systems are attractive alternatives to traditional influenza vaccines. We constructed recombinant nanosized virus-like particles based on a nuclear antigen of the hepatitis B virus. These particles expose on the surface the extracellular domain of the M2 protein of the highly pathogenic A(H1N1) 2009 influenza virus. The methods of production of these virus-like particles in Escherichia coli and their purification were developed. Experiments on animals show that M2sHBc particles are highly immunogenic in mice and provide complete protection against the lethal influenza challenge.

[Cowpea mosaic virus chimeric particles bearing ectodomain of matrix protein 2 (M2E) of influenza A virus: production and characteristics].

The epitope presentation system for ectodomain of M2-protein of influenza A virus (M2e) based on Cowpea Mosaic Virus (CPMV) was constructed for expression in plants Vigna unguiculata. CPMV is widely used as a vector for production of immunogenic chimeric virus particles (CVPs) bearing epitopes of different infectious human and animal pathogens. To produce chimeric CPMV virus particles in plants, two binary vectors were constructed bearing modified gene coding for S-coat protein of CPMV with insertions of M2e epitopes of human influenza and bird influenza viruses. Antigenic and immunogenic properties of CVPs obtained were investigated in mice immunization experiments and it was shown that they can induce anti-M2e IgG production and partial protection mice against challenge with low doses of flu virus. However, low infectivity and immunogenicity of CPMV chimeric particles indicate the need for further optimization of plant virus-based systems for M2e-epitopes presentation to use plants as a possible source of flu vaccines.

[Use of liposomes for vaccines design]. / Ispol'zovanie liposom dlia konstruirovaniia vaktsin.

Reviews reports on the creation of liposomal vaccines published during recent 25 years. Describes methods of antigen and immunomodulator incorporation in liposomes and their immunogenic properties. Presents data on development of influenza vaccines and prospects for their utilization as universal carriers of viral and bacterial antigens.

[The physicochemical characteristics of a chick embryo hydrolysate-based nutrient broth]. / Fiziko-khimicheskaia kharakteristika pitatel'nogo bul'ona na osnove gidrolizata kurinykh émbrionov.

The composition of dried nutrient broth, prepared on the basis of the fermentative hydrolysate of waste chick embryos, has been studied with the use of physicochemical analytical methods. The parameters of total and amino nitrogen, the content of amino acids, peptides, lipids, carbohydrates and microelements have been determined. The qualitative analysis of the peptide composition of the broth has been made. The heterogeneity of peptides with respect to their molecular weights (200--15,000 D and over) has been noted. As regards its physico-chemical composition, the broth is a valid medium, suitable for the cultivation of a wide spectrum of microorganisms.

[Physicochemical characteristics of an influenza virus population inactivated by gamma rays]. / Fiziko-khimicheskaia kharakteristika populiatsii virusa grippa, inaktivirovannogo gamma-luchami.

A study was made of the effect of 60Co-gamma-radiation on the integrity of particles of the influenza virus and on the structure of some of its proteins. The physicochemical changes in virions were shown to depend upon radiation conditions. A conclusion is made that it is possible to use gamma-rays in the production of a centrifuged virion influenza vaccine.