This is a proof-of-principle study demonstrating that the combination of a cholera toxin derived adjuvant, CTA1-DD, and lipid nanoparticles (LNP) can significantly improve the immunogenicity and protective capacity of an intranasal vaccine. We explored the self-adjuvanted universal influenza vaccine candidate, CTA1-3M2e-DD (FPM2e), linked to LNPs. We found that the combined vector greatly enhanced survival against a highly virulent PR8 strain of influenza virus as compared to when mice were immunized with FPM2e alone. The combined vaccine vector enhanced early endosomal processing and peptide presentation in dendritic cells and upregulated co-stimulation. The augmenting effect was CTA1-enzyme dependent. Whereas systemic anti-M2e antibody and CD4⁺ T-cell responses were comparable to those of the soluble protein, the local respiratory tract IgA and the specific Th1 and Th17 responses were strongly enhanced. Surprisingly, the lung tissue did not exhibit gross pathology upon recovery from infection and M2e-specific lung resident CD4⁺ T cells were threefold higher than in FPM2e-immunized mice. This study conveys optimism as to the protective ability of a combination vaccine based on LNPs and various forms of the CTA1-DD adjuvant platform, in general, and, more specifically, an important way forward to develop a universal vaccine against influenza.

这是一项原理验证研究，证明霍乱毒素衍生佐剂 CTA1-DD 和脂质纳米颗粒 (LNP) 的组合可以显着提高鼻内疫苗的免疫原性和保护能力。我们探索了与 LNP 相关的自佐剂通用流感候选疫苗 CTA1-3M2e-DD (FPM2e)。我们发现，与仅用 FPM2e 免疫小鼠相比，组合载体大大提高了针对高毒性 PR8 流感病毒株的存活率。联合疫苗载体增强了树突状细胞的早期内体加工和肽呈递，并上调了共刺激。增强效应是 CTA1 酶依赖性的。而全身抗 M2e 抗体和 CD4 ⁺T 细胞反应与可溶性蛋白的反应相当，局部呼吸道 IgA 和特异性 Th1 和 Th17 反应得到强烈增强。令人惊讶的是，肺组织在从感染中恢复后没有表现出大体病理学，并且 M2e 特异性肺驻留 CD4 ⁺ T 细胞比 FPM2e 免疫小鼠高三倍。这项研究对基于 LNP 和各种形式的 CTA1-DD 佐剂平台的联合疫苗的保护能力表示乐观，总的来说，更具体地说，这是开发通用流感疫苗的重要途径。