The Orthopoxvirus genus, especially variola virus (VARV), monkeypox virus (MPXV), remains a significant public health threat worldwide. The development of therapeutic antibodies against orthopoxviruses is largely hampered by the high cost of antibody engineering and manufacturing processes. mRNA-encoded antibodies have emerged as a powerful and universal platform for rapid antibody production. Herein, by using the established lipid nanoparticle (LNP)-encapsulated mRNA platform, we constructed four mRNA combinations that encode monoclonal antibodies with broad neutralization activities against orthopoxviruses. In vivo characterization demonstrated that a single intravenous injection of each LNP-encapsulated mRNA antibody in mice resulted in the rapid production of neutralizing antibodies. More importantly, mRNA antibody treatments showed significant protection from weight loss and mortality in the vaccinia virus (VACV) lethal challenge mouse model, and a unique mRNA antibody cocktail, Mix2a, exhibited superior in vivo protection by targeting both intracellular mature virus (IMV)-form and extracellular enveloped virus (EEV)-form viruses. In summary, our results demonstrate the proof-of-concept production of orthopoxvirus antibodies via the LNP-mRNA platform, highlighting the great potential of tailored mRNA antibody combinations as a universal strategy to combat orthopoxvirus as well as other emerging viruses.

正痘病毒属，特别是天花病毒（VARV）、猴痘病毒（MPXV），仍然是全世界重大的公共卫生威胁。针对正痘病毒的治疗性抗体的开发在很大程度上受到抗体工程和制造过程的高成本的阻碍。 mRNA 编码的抗体已成为快速抗体生产的强大且通用的平台。在此，通过使用已建立的脂质纳米颗粒（LNP）封装的mRNA平台，我们构建了四种编码单克隆抗体的mRNA组合，这些单克隆抗体具有针对正痘病毒的广泛中和活性。体内表征表明，在小鼠中单次静脉注射每种 LNP 封装的 mRNA 抗体可导致中和抗体的快速产生。更重要的是，mRNA 抗体治疗在痘苗病毒 (VACV) 致死攻击小鼠模型中显示出显着的体重减轻和死亡率保护作用，并且独特的 mRNA 抗体混合物 Mix2a 通过靶向细胞内成熟病毒 (IMV)-型和胞外包膜病毒（EEV）型病毒。总之，我们的结果证明了通过 LNP-mRNA 平台生产正痘病毒抗体的概念验证，凸显了定制 mRNA 抗体组合作为对抗正痘病毒以及其他新兴病毒的通用策略的巨大潜力。