Nelfinavir is an orally bioavailable competitive inhibitor of the human immunodeficiency virus. It potently inhibits HIV-1 (Ki=2nM) and HIV-2 protease in vitro. HIV-1 protease is important for the replication of the virus within the cell and the release of mature viral particles from the infected cell. Formulations containing nelfinavir have been used in combination with HIV reverse transcriptase inhibitors for the treatment of AIDS. Nelfinavir shows other antimicrobial and antiviral activity. It inhibits maturation and export of the Herpes Simplex 1 virus and the Kaposi's Sarcoma virus, replication of SARS-CoV and also replication of SARS-CoV-2, cause for the epidemic COVID-19. Has potent anti-cancer activity against a broad selection fo cancer cell types. Shown to induce apoptosis, autophagy, cell cycle arrest and endoplasmic reticulum stress, which consequently leads to cancer cell death. Shown to inhibit the Akt/PKB signaling pathway. It acts as an antifibrotic agent and is used to treat pulmonary fibrosis in patients with systemic sclerosis (SSc) and reduces inflammation by activating protein phosphatase 2 (PP-2) and blocking mitogen-activated protein kinases (MAPK) signaling in macrophages.