Fig. 2.

Simplified schematic of key steps and associated proteins involved in the invasion of the host cell by SARS-CoV-2. Binding of the SARS-CoV-2 spike to ACE2 is followed by action of the endosomal cysteine protease Cathepsin L [CTSL], resulting in fusion of viral and host cell membranes and release of the viral genome into the host cell cytoplasm. Amantadine has the potential to disrupt the process by down-regulation of CTSL by increasing the pH of endosomes, resulting in impaired viral entry and replication [20]