ACE2 and viral infectious disease: However, ACE2-IgG Fc fusion protein is endowed with FcRγ binding activity, which will promote viral invasion into FcRγ-expressing phagocytic cells, leading to increased viral infection and replication, or mediate immune complex formation, causing enhanced inflammation and immunopathology, an effect termed antibody-dependent enhancement (ADE), which is detrimental to COVID-19 patients [65,66].