Search Results (2)

Background/Objectives: Influenza vaccines require good thermal stability without the need for refrigerator storage. Although the fatty acid-conjugated hemagglutinin (Heg) vaccine antigen provides good stability in both solid and liquid states, its therapeutic effectiveness must be validated in vivo. This study aimed to investigate the immunogenicity of the thermally stabilized Heg-oleic acid conjugate (HOC) and compare it with native Heg as a reference. Method: To evaluate HOC immunogenicity, an enzyme-linked immunosorbent assay was used to measure hemagglutinin inhibition (HI) titers, serum IgG antibody titers (IgG1, IgG2a), and cytokine secretion levels (IFN-γ, IL-4) in BALB/c mice after intramuscular (IM) injection. Results: Thermally stabilized HOC induced higher and more sustained serum IgG1 and IgG2a responses than the native Heg vaccine antigen. IgG1 is typically associated with a Th2 response, whereas IgG2a is associated with a Th1 response. HOC appeared to enhance both responses, inducing a more balanced immune response. Moreover, HOC antigens stimulate broader immune responses, suggesting stronger and longer-lasting immune memory. The cytokine levels of IFN-γ (2.8-fold) and IL-4 (6-fold) were significantly increased in the HOC-immunized group compared to the Heg group. IFN-γ, a cytokine that activates the Th1 immune response, demonstrated the enhanced ability of HOC to induce a Th1 response. IL-4, a cytokine that promotes the Th2 response, indicated that HOC also strongly induced a Th2 response. The thermal stability of HOC antigens was crucial for maintaining their structural integrity, enabling the continuous exposure to the stable antigen without denaturation. This allows immune cells to recognize stable antigens efficiently and form long-term immune memory. Conclusions: The stability of HOC antigens enhanced the antigen processing efficiency of antigen-presenting cells (APCs) and stimulated immune responses. The fatty acid-conjugated vaccine antigen could provide improved storage stability but also enhance immunogenic efficacy compared to the native antigen, supporting its potential for further applications. Full article

Subunit vaccines consist of non-genetic material, such as peptides or proteins. They are considered safe because they have fewer side effects; however, they have low immunogenicity when used alone. We aimed to enhance the immune response of peptide-based vaccines by using self-assembled multimeric peptide amphiphiles (PAs). We designed two epitope PAs by conjugating epitope peptides from Enterovirus 71 (EV71) virus particle (VP) 1 and VP3 capsid proteins with different fatty acid chain lengths (VP1PA and VP3PA). These PAs self-assembled into supramolecular structures at a physiological pH, and the resulting structures were characterized using atomic force microscopy. Multi-epitope PAs (m-PAs) consisted of a 1:1 mixture of VP1PA and VP3PA solutions. To evaluate immunogenicity, m-PA constructs were injected with adjuvant subcutaneously into female Balb/c mice. Levels of antigen-specific immunoglobulin G (IgG) and IgG1 in m-PA-injected mice serum samples were analyzed using ELISA and Western blotting. Additionally, cytokine production stimulated by each antigen was measured in splenocytes cultured from immunized mice groups. We found that m-PA showed improved humoral and cellular immune responses compared to the control and peptide groups. The sera from m-PA immunized mice group could neutralize EV71 infection and protect host cells. Thus, self-assembled m-PAs can promote a protective immune response and can be developed as a potential platform technology to produce peptide vaccines against infectious viral diseases. Full article