The aim of the study was to develop amphiphilic poly(N-vinylpyrrolidone) (PVP) nanoparticles (NPs) loaded with DNA plasmids encoding Gn and Gc glycoproteins of the Rift Valley fever virus (RVFV) and to study the humoral response in vivo. DNA plasmids were protected from extracellular nucleases by loading in NPs from PVP derivatives modified with amino acids β-alanine (Ala7-PVPOD4000) or glycine (Gly7.5-PVP-OD4000) fabricated by the original self-assembly technique. The obtained NPs were administered in mice and the enhancement of humoral response compared to this one in case of immunization with native DNA plasmids was demonstrated. The NPs loaded with DNA plasmids are promising for the fabrication of various DNA particulate vaccines.

Objectives The aim of the current study was to develop biodegradable alginate (ALG)/poly- l -lysine (PLL) microcapsules (MC) with entrapped plasmids expressing Gn and Gc glycoproteins of Rift Valley Fever virus (RVFV) and to evaluate the humoral immune response in mice. Results Expressing phRVF/Gn and phRVF/Gc plasmids which encode full-sized Gn and Gc glycoproteins and contain signal fusion protein F sequences of human parainfluenza (HPIV-1) were constructed. To protect the plasmids from cleavage by extracellular nucleases, they were entrapped into multilayer ALG/PLL microcapsules by layer-by-layer technique. To study the efficacy of humoral immune response, both native and microencapsulated plasmids were injected intramuscular into BALB/c mice. The humoral response in the mice immunized with free plasmids was characterized by virus-neutralizing antibody induction (with titres 1:4 to 1:8), while the injection of microencapsulated plasmids allowed to increase the titre level (from 1:16 to 1:32). Conclusion The plasmids microencapsulated in biodegradable MC could be promising for development of DNA vaccines against RVFV.

In this study an universal method for preparation of biodegradable microcapsules for antigen entrapment was proposed and optimized. The multilayer microcapsules were prepared by layer-by-layer adsorption of various polyelectrolytes (such as alginate, poly- L -lysine, κ-carrageenan, chitosan and dextran derivatives). High entrapment efficiency of protein and plasmid DNA (non less than 90%) was shown. To carry out in vivo tests, a set of microcapsules with entrapped pTKShi plasmid encoding the E2 polypeptide of classical swine fever was prepared. It was shown that an injection of these microcapsules into mice induced an immune response. The highest antibody titers of mouse blood sera were got after immunization by microcapsules based on modified dextran/carrageenan and modified chitosan/carrageenan. The proposed method for antigen entrapment in biodegradable microcapsules could be used for development of encapsulated vaccines of a new generation (DNA-vaccines).

A general method for the preparation of biodegradable microcapsules capable of antigen inclusion is suggested. Multilayer microcapsules were obtained by the method of level-by-level sorption of various polyelectrolytes (alginate, poly-L-lysine, kappa-carrageenan, and chitosan and dextran derivatives). High inclusion efficiency was found for protein and plasmid DNA (no less than 90%). A series of microcapsules with included pTKShi plasmid that incorporated a genome site encoding the E(2) polypeptide of the classic pig plague virus were obtained for carrying out in vivo experiments. It was shown that introduction to mice of microcapsules with the included pTKShi plasmid induced an immune response. The highest antibody titers of the mouse blood sera were obtained in immunization by microcapsules based on the modified dextran/carrageenan and modified chitosan/carrageenan. The method of antigen inclusion into biodegradable microcapsules could be used for the development of encapsulated vaccines of a new generation (DNA vaccines).

Potentially hemocompatible alginate-chitiosan microparticles and microcapsules coated with a semipermeable membrane with incorporated glycoconjugates were synthesized. The membrane acts as a barrier, which keeps the incorporated glycoconjugate from going outside but permits antibodies to penetrate inside and specifically bind to antigens, high-molecular polysaccharide conjugates. The supports obtained are highly competitive in sorption capacity with Sepharose modified by the same oligosaccharides.