3.1.3 Integrins
Recently, Sigrist et al suggested that 2019-nCoV may also use integrins as cell receptors in host cells, binding to them through a conserved RGD (403–405: Arg-Gly-Asp) motif in receptor-binding domain of S protein that is absent from other coronaviruses (Sigrist et al., 2020). The conformational changes due to ACE2 binding expose the RGD containing region. Different viruses like Ebola virus (Schornberg et al., 2009), human papillomavirus (Yoon et al., 2001), HIV-1 (Monini et al., 2012) and EBV (Tugizov et al., 2003) use integrins for cell attachment or entry. The antibody natalizumab (α4β1/β7 integrin antagonist) for the treatment of multiple sclerosis/Crohn’s disease and the small molecule tirofiban (αIIbβ3 inhibitor) for the treatment of acute coronary syndrome are the known inhibitors of integrin (Ley et al., 2016). These studies confirm that inhibiting the integrin scan impede some coronaviruses from entering the host cells is considered as a prolific target for antiviral drug discovery.