Influenza a virus: Investigation of novel therapeutic treatments and underlying mechanisms

Influenza viruses (IVs) are one of the most widespread, medically important family of viruses. One of the key characteristics of IVs, is the large and diverse host species pool, owed to the characteristic rapid evolution this family of viruses undergo, enabling the successful global spread. This rapid evolution is especially important in influenza A virus (IAV) infections. All current antiviral drugs, which target the viral proteins directly, lead to resistance. Seasonal infection by IVs are the cause of up to 650,000 deaths worldwide annually, whilst the potential for a pandemic variant emerging, which would likely lead to an even greater magnitude of mortalities, is high. Therefore, the requirement for novel treatments is essential. Here Affimer molecules, often termed ‘antibody mimics’, due to characteristic high affinity and specificity were investigated. Affimer molecules were isolated, specific to the IAV glycoprotein hemagglutinin (HA), which is crucial for facilitating entry to host cells. Potent neutralisers of multiple IAV strains have been isolated and characterised both biochemically and structurally. In which Affimer molecules were found to prevent entry, through the disruption of IAVs interaction with the host-cell receptor. Further still, structural information reveals the interaction between one Affimer molecule and HA induces a rare conformational change to HA. These findings, give promise to a novel method of treating IAV infection, with the potency of antibody treatment, whilst removing many of the drawbacks of these molecules. The investigation of IAV therapeutics, through indirect methods are also investigated here, in which the role of potassium ions (K+) during IAV infection was explored. Ion channel modulators are a large family of FDA approved drugs used for the treatment of channelopathies. Here, broad-spectrum potassium channel (K+ channel) inhibitors were exploited, revealing inhibition of multiple strains of IAV, suggesting inhibition of a conserved mechanism required for infection. This mechanism was further characterised by biochemical and visual investigation, which agree with recent findings in the literature, that K+ plays a role in the early stages of IAV infection, specifically as it passes through the endocytic pathway. Strucutral work shows this ionic prompt, increases the efficiency of the disassembly of the matrix layer, crucial for the release of viral ribonuclearproteins (vRNPs). Ultimately, this work highlights the potential for alternative treatments of IAV infection, alongside providing further insight into IAVs mechanism of infection.