Cyclamen europaeum (Cyclamen purpurascens) extract as adjuvant for nasal immunization of mice with influenza antigens

The article describes the first attempt to use the juice and extract of Cyclamen europaeum (Cyclamen purpurascens) tubers as an adjuvant for intranasal immunization of mice with influenza antigens. The concentration of antigens used for immunization was 300 μg/ml for each subtype. The adjuvant was added at the concentration of 10 and 20 mg/ml. Blood serum was studied using the hemagglutination inhibition reaction (HI) and enzyme immunoassay (ELISA). After two immunizations with a dose of 7.5 μg, the maximum inverse titers to the H1/H3/B components in the HI were 320/80/80, respectively. The administration of an intranasal comparator without an adjuvant did not result in seroconversion which can be detected by the HI. The analysis of the blood sera of mice, immunized intranasally by the antigen only, showed no increase in the antibody levels between the first and second injections. For mice immunized intranasally by a preparation containing 10 mg/ml (0.5 mg per 50 μl dose) of adjuvant the ELISA detected a significant growth of antibody levels for all components, and GMT antibody levels were comparable to GMT antibody levels after a single intramuscular injection of 5 μg of each antigen. Despite a significant serum titer dispersion (which the authors explain by the impossibility of ensuring absolute uniformity in administration of 50 μl of substance via the nasal route) the use of the extract as an adjuvant for intranasal immunization of mice with highly concentrated influenza antigens showed a significant humoral response. The level of this response after two immunizations in some animals was comparable to that after intramuscular administration. The obtained data open the possibility of using Cyclamen europaeum tuber extract or its chemical analogues in further studies in guinea pigs, ferrets or other animal models in order to develop an efficacious adjuvant for intranasal immunization.

экстракт, цикламен, вакцина, адъювант, интраназальный, иммунизация, грипп, респираторный, инфекция, extract, cyclamen, vaccine, adjuvant, intranasal, immunization, influenza, respiratory, infection

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