Influenza A virus H5N1 subtype (H5N1)

The Influenza A virus H5N1 subtype, commonly known as "avian influenza" or "bird flu," is a highly pathogenic zoonotic virus that poses a significant threat to global health due to its potential for high mortality in humans and its risk of initiating a pandemic [12, 17]. Strictly speaking, H5N1 is a whole pathogen rather than a single molecular target; however, it contains several critical proteins that are the focus of therapeutic intervention, most notably the surface glycoproteins Hemagglutinin (HA) and Neuraminidase (NA), as well as the M2 ion channel and the viral polymerase complex [1, 13, 15]. Hemagglutinin mediates viral entry by binding to host sialic acid receptors, while Neuraminidase facilitates the release of progeny virions by cleaving sialic acid residues [5, 15]. Pharmacological agents such as oseltamivir and zanamivir target the NA enzyme to prevent viral spread, whereas adamantanes like amantadine inhibit the M2 channel to prevent viral uncoating [1, 10, 11]. Recent advancements have also introduced baloxavir marboxil, which targets the viral cap-dependent endonuclease to inhibit genome replication [7, 10]. A major challenge in targeting H5N1 is its high mutation rate, which leads to the frequent emergence of drug-resistant variants and necessitates the development of universal vaccines and combination therapies [1, 14, 17].

Other names

H5N1Bird flu virusHighly pathogenic avian influenza virusHPAI H5N1Avian influenza A(H5N1)

Inhibition of viral neuraminidase to prevent virion release; blocking of M2 proton channels to inhibit viral uncoating; and inhibition of the viral polymerase complex (e.g., cap-dependent endonuclease or RNA-dependent RNA polymerase) to block viral genome replication.