[Adjuvant effect of dispersed fullerene C60 on the immune response to constructs harboring amino acid and nucleotide sequences of hepatitis C virus nonstructural NS5B protein].

INTRODUCTION: A vaccine against hepatitis C has not yet been developed. Recombinant proteins and plasmids encoding hepatitis C virus (HCV) proteins, the components of candidate vaccines, induce a weak immune response and require the use of adjuvants. The aim of the work was to study the adjuvant action of an aqueous solution of fullerene C60 during immunization of mice with HCV recombinant protein NS5B (rNS5B) that is an RNA-dependent RNA polymerase, or with NS5B-encoding pcNS5B plasmid. MATERIALS AND METHODS: An aqueous solution of dispersed fullerene (dnC60) was obtained by ultrafiltration. C57BL/6 mice were immunized with rNS5B subcutaneously, pcNS5B intramuscularly mixed with different doses of dnC60 three times, then the humoral and cellular response to HCV was evaluated. RESULTS: Mice immunization with rNS5B in a mixture with dnC60 at doses of 250 g/mouse significantly induced humoral response: a dose-dependent increase in IgG1 antibody titers was 720 times higher than in the absence of fullerene. There was no increase in the cellular response to rNS5B when administered with dnC60. The humoral response to DNA immunization was weak in mice of all groups receiving pcNS5B. The cellular response was suppressed when the plasmid was injected in a mixture with dnC60. CONCLUSIONS: Dispersed fullerene dnC60 is a promising adjuvant for increasing the immunostimulating activity of weakly immunogenic proteins including surface and other HCV proteins, important for a protective response. Further research is needed to enhance the ability of dnC60 to boost the cellular immune response to the components of the candidate vaccine.

Immunological properties of allergen chemically modified with synthetic copolymer of N-vinylpyrrolidone and maleic anhydride.

Several conjugates of model allergen ovalbumin (OA) and the copolymer of N-vinyl pyrrolidone and maleic anhydride (VMA) modified with epsilon-aminocaproic acid (Acp) were prepared in different OA/Acp-VMA ratios. All conjugates were separated by ultrafiltration and analyzed by HPLC. Their compositions were determined by amino acid analysis and UV spectrometry. To detect immunogenicity, all conjugates were injected intraperitoneally into (CBAxC57BL/6)F1 mice three times in 3-week intervals in OA doses equivalent to 0.5, 10, and 100 micrograms/mouse. Only the conjugate containing 20%OA (OA(20%)-Acp-VMA) did not induce significant quantities of anti-OA IgE, but did induce anti-OA IgG antibodies in dose-dependent manner comparable to that of unmodified OA. Mixtures of OA and Acp-VMA or OA modified only with VMA without Acp activation with Acp induced dose-dependent anti-OA IgE and IgG antibody formation comparable to that of OA. Using passive cutaneous anaphylaxis, RAST inhibition and leukocyte histamine release, a significant reduction of allergenicity was noted using OA(20%)-Acp-VMA. This conjugate stimulated activation of the OA-specific T-cell hybrid 3DO-548 comparable to that of unconjugated OA. During experimental allergen-specific hyposensitization with OA(20%)-Acp-VMA, suppression of anti-OA IgE response and elevation of anti-OA IgG responses were noted when compared with unmodified OA. Selective blockade of B-cell epitopes of allergen may occur using the carrier Acp-VMA to reduce allergenicity while not affecting T-cell epitopes, thereby preserving immunogenicity. This approach of chemical modification of allergen suggests new opportunities in the creation of preparations for allergen-specific immunotherapy.