SARS-CoV-2 accessory protein ORF3a (ORF3a)

SARS-CoV-2 accessory protein ORF3a is a multifunctional viral protein and the largest accessory protein encoded by the SARS-CoV-2 genome. It primarily functions as a viroporin, forming a nonselective cation channel that is permeable to calcium and potassium ions, which is essential for viral entry, replication, and egress through the lysosomal exocytosis pathway [1, 3, 10]. ORF3a is a major virulence factor that contributes to the pathogenesis of COVID-19 by activating the NLRP3 inflammasome, leading to the production of pro-inflammatory cytokines and the induction of a cytokine storm [2, 5, 9]. It also disrupts host cellular processes, including the inhibition of autophagosome-lysosome fusion and the down-regulation of MHC-I surface expression, thereby facilitating viral survival and immune evasion [8, 14]. Clinically, ORF3a is associated with severe disease outcomes, tissue damage in multiple organs, and potential long-term complications such as neuroinflammation and cardiac arrhythmias [13, 15]. Due to its critical roles in the viral life cycle and host inflammatory response, ORF3a is considered a promising therapeutic target for the development of novel antiviral drugs and the management of COVID-19 [3, 7, 10].

Other names

Protein 3aORF3a proteinViroporin 3aX1U274

Inhibition of viroporin ion channel activity to block viral release and suppression of NLRP3 inflammasome activation to reduce hyper-inflammation.