Influenza A virus nonstructural protein 1 and nonstructural protein 2 (NS1/NS2)

Influenza A virus nonstructural proteins NS1 and NS2 (also known as Nuclear Export Protein, NEP) are essential viral factors encoded by the eighth genomic segment through alternative splicing [1, 2]. NS1 is a multifunctional virulence factor that primarily functions as an antagonist of the host's innate immune response, specifically by inhibiting the production and activity of type I interferons (IFN) [1, 3]. It achieves this by sequestering double-stranded RNA and interacting with host proteins such as RIG-I, TRIM25, and CPSF30, thereby preventing the detection of viral RNA and the processing of host mRNAs [1, 4]. NS2/NEP acts as an adaptor for the nuclear export of viral ribonucleoprotein (vRNP) complexes, a critical step for the assembly of new virions, and also plays a role in regulating the balance between viral transcription and replication [2, 5]. Due to their essential roles in viral pathogenesis and replication, both proteins are attractive targets for the development of novel antiviral therapies, particularly to overcome resistance to existing drugs like neuraminidase inhibitors [1, 4]. Experimental small molecules such as JJ3297 and A22 have been shown to inhibit NS1 by disrupting its interaction with host factors, though no drugs targeting these proteins are currently FDA-approved [4, 5]. Targeting these nonstructural proteins offers a strategy to restore the host's natural antiviral defenses while simultaneously blocking the viral replication cycle.

Other names

NS1NS2NEPNuclear export proteinNon-structural protein 1Non-structural protein 2Segment 8 proteins

Inhibition of the NS1-CPSF30 interaction to restore host mRNA processing, sequestration of the NS1 RNA-binding domain to prevent interferon antagonism, and disruption of NS2-mediated nuclear export of viral ribonucleoproteins.