Enhancing protective immunity in the respiratory tract is crucial to combat influenza infection and transmission. Developing mucosal universal influenza vaccines requires effective delivery platforms to overcome the respiratory mucosal barrier and stimulate appropriate innate immune reactions, thereby bridging adaptive immune responses with minimal necessary inflammation. Meanwhile, the vaccine platforms must be biocompatible. This study employed cell-derived extracellular vesicles (EVs) as a mucosal universal influenza vaccine platform. By conjugating influenza hemagglutinin (HA) onto EV surfaces through HA-receptor interaction, we achieved an upside-down (inverted) influenza HA configuration that exposed the conserved HA stalk region while partially hiding the globular head domain. Intranasal immunization with the resulting EVs induced robust HA stalk- and virus-specific serum antibody and mucosal immune responses in mice, protecting against heterologous virus infection. Notably, EVs derived from the lung epithelial cell line A549 induced superior cross-reactive antibodies and enhanced protection upon intranasal immunization. EVs conjugating multivalent HA elicited broadly cross-reactive antibody and cellular responses against different influenza strains. Our results demonstrated that EVs conjugating multiple inverted HAs represented an effective strategy for developing a mucosal universal influenza vaccine.

中文翻译：

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用结合倒置流感 HA 的细胞外囊泡进行免疫，在小鼠中引发 HA 茎特异性免疫和交叉保护。


增强呼吸道的保护性免疫力对于对抗流感感染和传播至关重要。开发粘膜通用流感疫苗需要有效的递送平台来克服呼吸道粘膜屏障并刺激适当的先天免疫反应，从而以最小的必要炎症弥合适应性免疫反应。同时，疫苗平台必须具有生物相容性。本研究采用细胞来源的细胞外囊泡 （EV） 作为粘膜通用流感疫苗平台。通过 HA 受体相互作用将流感血凝素 （HA） 结合到 EV 表面，我们实现了一种倒置（倒置）的流感 HA 构型，该构型暴露了保守的 HA 柄区域，同时部分隐藏了球状头部结构域。用所得 EV 进行鼻内免疫在小鼠中诱导了强大的 HA 茎和病毒特异性血清抗体和粘膜免疫反应，从而防止异源病毒感染。值得注意的是，源自肺上皮细胞系 A549 的 EVs 诱导了卓越的交叉反应性抗体，并在鼻内免疫后增强了保护作用。偶联多价 HA 的 EVs 引发了针对不同流感毒株的广泛交叉反应性抗体和细胞反应。我们的结果表明，偶联多个倒置 HA 的 EV 代表了开发粘膜通用流感疫苗的有效策略。