**4. Antiviral molecular targets and drug development strategies against COVID-19**

Generally, a probable antiviral drug target is a molecule (often a protein) with a vital role in the life cycle of the planned virus [14, 15]. Accordingly, to date, several structural and accessory proteins from *SARS-CoV-2* have been subjected to the drug-discovery process. Consistent with the approved information about the *SARS-CoV-2* life cycle, eight steps including virus binding, fusion to host cell, RNA release, translation, proteolysis, replication and translation, viral assembly, and release could be planned to investigate potential anti-COVID-19 drugs. Among the mentioned steps, virus attachment and entry, proteolysis, and replication have received more attention due to more available data about the key proteins in the steps as well as the high similarity of these steps between coronaviruses [16, 17].

In the following sections, the key steps in *SARS-CoV-2* life cycle are discussed in the light of drug development against COVID-19.
