Human immunodeficiency virus (HIV) is a lentivirus that causes acquired immunodeficiency syndrome (AIDS), a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections. Envelope glycoprotein GP120 (or gp120) is a glycoprotein exposed on the surface of the HIV envelope. The 120 in its name comes from its molecular weight of 120 kDa. gp120 is essential for virus entry into cells as it plays a vital role in seeking out specific cell surface receptors for entry. Synonyms: Monoclonal HIV1 integrase antibody, Anti-HIV1 integrase antibody, HIV-1 Integrase antibody, HIV antibody, Human Immunodeficiency virus 1 antibody, IN antibody, Integrase antibody, p31 antibody.