COVID-19.SARS-CoV-2, the virus that causes COVID-19, attacks the body in multiple steps. Gaining entry into cells deep within the lungs and hijacking the human host cell’s machinery to churn out copies of itself are two of the earliest steps -- both essential for viral infection.The new study, published in the journal Science Advances, found that some existing compounds can inhibit both the main protease (Mpro), a key viral protein required for SARS-CoV-2 replication inside human cells, and the lysosomal protease cathepsin L, a human protein important for viral entry into host cells."If we can develop compounds to shut down or significantly reduce both processes -- viral entry and viral replication -- such dual inhibition may enhance the.