Early cross-coronavirus reactive signatures of humoral immunity against COVID-19
https://www.science.org/doi/10.1126/sciimmunol.abj2901
>S2-specific responses are selectively enriched in survivors of COVID-19
>cCoV responses are enriched in survivors early in infection course
>Expanded S2-specific FcR binding antibodies are selectively enriched in asymptomatic infection

COVID-19生存者ではS2への免疫反応が強く
特に感染初期でHCoV-OC43交差反応がある
とりわけ無症状感染者ではFc受容体に結合する抗体価が高い

>Unlike the potent neutralizing activity of antibodies against RBD,
>S2-specific antibodies are more weakly neutralizing (66–68) and thus
>likely provide protection through additional humoral mechanisms (16).

RBD抗体と比べS2抗体の中和活性は弱いので他の機構による防御作用がある

>In our cohort of patients with acute COVID-19, S2-specific antibodies
>with FcR binding capabilities, rather than S2-titers alone,
>were among the strongest correlates of protective immunity against death.
>Moreover, S2-specific antibody functions were selectively augmented
>in asymptomatic SARS-CoV-2 infection, suggesting that the ability of
>these antibodies to recruit specific innate immune effector functions
>may be key to their protective activity.

その機構はFc受容体への結合であり防御能力と強い相関がある
とりわけ無症状感染者では自然免疫を誘導するエフェクターが抗体で励起されている