PROS1 and viral infectious disease: Taken together, the results obtained from the MD analysis, the ACE2/S protein binding analysis, and the TMPRSS-2 expression study indicate a multifunctional MOA for EF, operating on various levels, i.e., partial interaction with the S protein, and concomitant inhibition of cellular receptors required for viral attachment and invasion of the host, as well as impaired expression of a cellular protease, which is essential for SARS-CoV-2 membrane fusion and virus infection.