Influenza A virus nonstructural protein 1 (NS1)

Influenza A virus nonstructural protein 1 (NS1) is a multifunctional viral protein, highly conserved among influenza A strains, and ranges in size from 215–237 amino acids. It is essential for efficient viral replication and pathogenesis by antagonizing host antiviral defenses, particularly the type I interferon response. NS1 acts by multiple mechanisms, including binding double-stranded RNA, inhibiting host mRNA maturation and export (via interactions with factors such as CPSF30 and the NXF1–NXT1 mRNA export complex), and blocking activation of the dsRNA-activated protein kinase PKR. NS1 has two main domains—an N-terminal RNA-binding domain and a C-terminal effector domain—joined by a flexible linker, allowing it to interact with a variety of host cellular factors. Its ability to structurally adapt enables broad interactions needed for immune evasion and successful viral propagation in host cells. Targeting NS1 is a promising antiviral strategy, as it is critical for virus survival but not present in the host, though no NS1-targeted therapies are yet approved.

Other names

NS1Influenza nonstructural protein 1IAV NS1Non-structural protein 1NS1A protein

Inhibitors would act by blocking NS1’s RNA-binding function or its interaction with host factors, thereby restoring host antiviral responses and blocking viral replication.