Influenza A virus, H1N1 subtype (H1N1)

Influenza A virus, H1N1 subtype is an enveloped, negative-sense single-stranded RNA virus belonging to the Orthomyxoviridae family[2][4]. It is characterized by its surface glycoproteins hemagglutinin (H1) and neuraminidase (N1), which define the viral subtype[2][8]. H1N1 has caused notable human pandemics, including in 1918 and 2009, and is a major cause of seasonal influenza worldwide[2][3]. The viral hemagglutinin mediates attachment and entry into host epithelial cells by binding sialic acid receptors, while neuraminidase enables release of newly formed virions[1][3][5]. The H1N1 genome encodes several proteins, including the RNA-dependent RNA polymerase (PB1, PB2, PA), nucleoprotein, and matrix proteins[4][5]. Its high mutability results in frequent antigenic changes, necessitating continual surveillance and vaccine updates. H1N1 remains a principal target for antiviral drugs and seasonal vaccines, but is also associated with ongoing safety challenges due to rapid antigenic evolution and the potential for severe respiratory disease in susceptible individuals[5][8].

Other names

Influenza A H1N1H1N1 influenza virusSwine flu virus (commonly for the 2009 pandemic strain)Influenza A virus sub-type H1N1

Neuraminidase inhibitors (oseltamivir, zanamivir, peramivir): block virion release from infected cells by inhibiting viral neuraminidase Cap-dependent endonuclease inhibitor (baloxavir marboxil): inhibits viral mRNA synthesis M2 ion channel blockers (amantadine, rimantadine): block viral uncoating (but most H1N1 are now resistant)