Adjuvants are chemical/
biological substances that are used in
vaccines to increase the immunogenicity of
antigens. A few adjuvants have been developed for use in human
vaccines because of their limitations including lack of efficacy, unacceptable local or systemic toxicity, the difficulty of manufacturing, poor stability, and high cost. For that reasons, novel adjuvants/adjuvant systems are under search.
Astragaloside VII (AST-VII), isolated from Astragalus trojanus, exhibited significant cellular and humoral immune responses. The
polysaccharides (APS) obtained from the roots of Astragalus species have been used in
traditional Chinese medicine and possess strong immunomodulatory properties. In the present study, the immunomodulatory effects of a newly developed nanocarrier system (APNS: APS containing carrier) and its AST-VII containing formulation (ANS: AST-VII + APNS), on seasonal
influenza A (H3N2)
vaccine were investigated. Inactivated H3N2 alone or its combinations with test compounds/formulations were intramuscularly injected into Swiss albino mice. Four weeks after immunization, the immune responses were evaluated in terms of antibody and
cytokine responses as well as splenocyte proliferation. APNS demonstrated Th2 mediated response by increasing
IgG1 antibody titers, whereas ANS showed response towards Th1/Th2 balance and Th17 by producing of IFN-γ,
IL-17A and
IgG2a. Based on these results, we propose that APNS and ANS are good candidates to be utilized in seasonal
influenza A
vaccines as adjuvants/carrier systems.