Ana-Sosa-Batiz Fernanda, Verma Shailendra Kumar, Shafee Norazizah, Miller Robyn, Conner Chris, Hastie Kathryn M, Timis Julia, Maule Erin, Nguyen Michael N, Tran Linda, Varghese Krithik, Madany Henry, Street Audrey Elizabeth, Zandonatti Michelle, Moi Meng Ling, Jarnagin Kurt, Webb David R, Saphire Erica Ollmann, Kim Kenneth, Shresta Sujan
Center for Vaccine Innovation, La Jolla Institute for Immunology, La Jolla, CA, 92037, USA.
Center for Vaccine Innovation, La Jolla Institute for Immunology, La Jolla, CA, 92037, USA; Synbal Inc., 1759 Yorktown Rd., San Mateo, CA, 94402, USA.
EBioMedicine. 2025 Mar;113:105619. doi: 10.1016/j.ebiom.2025.105619. Epub 2025 Feb 27.
Despite the importance of vaccination- and infection-elicited antibodies (Abs) to SARS-CoV-2 immunity, current mouse models do not fully capture the dynamics of Ab-mediated immunity in vivo, including potential contributions of the neonatal Fc receptor, encoded by FCGRT.
We generated triple knock-in (TKI) mice expressing human ACE2, TMPRSS2, and FCGRT; and evaluated the protective efficacy of anti-SARS-CoV-2 monoclonal Abs (mAbs) and plasma from individuals with immunity elicited by vaccination alone plus SARS-CoV-2 infection-induced (hybrid) immunity.
A human anti-SARS-CoV-2 mAb harbouring a half-life-extending mutation, but not the wild-type mAb, exhibited prolonged half-life in TKI mice and protected against lung infection with Omicron BA.2, validating the utility of these mice for evaluating therapeutic Abs. Pooled plasma from individuals with hybrid immunity to Delta, but not from vaccinated-only individuals, cleared infectious Delta from the lungs of TKI mice (P < 0.01), even though the two plasma pools had similar Delta-binding and -neutralising Ab titres in vitro. Similarly, plasma from individuals with hybrid Omicron BA.1/2 immunity, but not hybrid Delta immunity, decreased lung infection (P < 0.05) with BA.5 in TKI mice, despite the plasma pools having comparable BA.5-binding and -neutralising titres in vitro. Depletion of receptor-binding domain-targeting Abs from hybrid immune plasma abrogated their protection against infection.
These results demonstrate the utility of TKI mice as a tool for the development of anti-SARS-CoV-2 mAb therapeutics, show that in vitro neutralisation assays do not accurately predict in vivo protection, and highlight the importance of hybrid immunity for eliciting protective anti-receptor-binding domain Abs.
This work was funded by grants from the e-Asia Joint Research Program (N10A650706 and N10A660577 to MLM, in collaboration with SS); the NIH (U19 AI142790-02S1 to EOS and SS and R44 AI157900 to KJ); the GHR Foundation (to SS and EOS); the Overton family (to SS and EOS); the Arvin Gottlieb Foundation (to SS and EOS), the Prebys Foundation (to SS); and the American Association of Immunologists Fellowship Program for Career Reentry (to FASB).
尽管疫苗接种和感染引发的抗体（Abs）对严重急性呼吸综合征冠状病毒2（SARS-CoV-2）免疫至关重要，但目前的小鼠模型并未完全捕捉到体内抗体介导免疫的动态变化，包括由新生儿Fc受体（由FCGRT编码）的潜在作用。
我们构建了表达人血管紧张素转换酶2（ACE2）、跨膜丝氨酸蛋白酶2（TMPRSS2）和FCGRT的三基因敲入（TKI）小鼠；并评估了抗SARS-CoV-2单克隆抗体（mAbs）以及仅通过疫苗接种引发免疫的个体加上SARS-CoV-2感染诱导（混合）免疫的个体的血浆的保护效力。
一种携带延长半衰期突变的人抗SARS-CoV-2 mAb，而非野生型mAb，在TKI小鼠中表现出延长的半衰期，并能预防奥密克戎BA.2引起的肺部感染，验证了这些小鼠在评估治疗性抗体方面的实用性。来自对德尔塔有混合免疫的个体的混合血浆，而非仅接种疫苗个体的血浆，清除了TKI小鼠肺部的感染性德尔塔病毒（P < 0.01），尽管这两种血浆在体外具有相似的德尔塔结合和中和抗体滴度。同样，来自对奥密克戎BA.1/2有混合免疫的个体的血浆，而非对德尔塔有混合免疫的个体的血浆，在TKI小鼠中减少了BA.5引起的肺部感染（P < 0.05），尽管这些血浆在体外具有相当的BA.5结合和中和滴度。从混合免疫血浆中去除靶向受体结合域的抗体消除了它们对感染的保护作用。
这些结果证明了TKI小鼠作为开发抗SARS-CoV-2 mAb治疗药物工具的实用性，表明体外中和试验不能准确预测体内保护作用，并强调了混合免疫在引发保护性抗受体结合域抗体方面的重要性。
本研究由以下基金资助：东亚联合研究计划（N10A650706和N10A660577授予MLM，并与SS合作）；美国国立卫生研究院（U19 AI142790 - 02S1授予EOS和SS，R44 AI157900授予KJ）；GHR基金会（授予SS和EOS）；奥弗顿家族（授予SS和EOS）；阿尔文·戈特利布基金会（授予SS和EOS）；普雷比斯基金会（授予SS）；以及美国免疫学家协会职业再入奖学金计划（授予FASB）。
