TMPRSS2 and infection: Moreover, other crucial proteins for the infection and spread of SARS-CoV-2 in the CNS have also been identified, including NRP1, transmembrane protease serine 2 (TMPRSS2), basigin, and cathepsin L (Burks et al., 2021; Song et al., 2021; Welcome and Mastorakis, 2021).