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| Title | Exploiting the Affimer platform against influenza A virus. |
|---|---|
| Journal, issue, pages | mBio, Vol. 15, Issue 8, Page e0180424, Year 2024 |
| Publish date | Aug 14, 2024 |
 Authors | Oliver Debski-Antoniak / Alex Flynn / David P Klebl / Moisés H Rojas Rechy / Christian Tiede / Ian A Wilson / Stephen P Muench / Darren Tomlinson / Juan Fontana /   |
| PubMed Abstract | Influenza A virus (IAV) is well known for its pandemic potential. While current surveillance and vaccination strategies are highly effective, therapeutic approaches are often short-lived due to the ...Influenza A virus (IAV) is well known for its pandemic potential. While current surveillance and vaccination strategies are highly effective, therapeutic approaches are often short-lived due to the high mutation rates of IAV. Recently, monoclonal antibodies (mAbs) have emerged as a promising therapeutic approach, both against current strains and future IAV pandemics. In addition to mAbs, several antibody-like alternatives exist, which aim to improve upon mAbs. Among these, Affimers stand out for their short development time, high expression levels in , and animal-free production. In this study, we utilized the Affimer platform to isolate and produce specific and potent inhibitors of IAV. Using a monomeric version of the IAV trimeric hemagglutinin (HA) fusion protein, we isolated 12 Affimers that inhibit IAV infection . Two of these Affimers were characterized in detail and exhibited nanomolar-binding affinities to the target H3 HA protein, specifically binding to the HA1 head domain. Cryo-electron microscopy (cryo-EM), employing a novel spray approach to prepare cryo-grids, allowed us to image HA-Affimer complexes. Combined with functional assays, we determined that these Affimers inhibit IAV by blocking the interaction of HA with the host-cell receptor, sialic acid. Furthermore, these Affimers inhibited IAV strains closely related to the one used for their isolation. Overall, our results support the use of Affimers as a viable alternative to existing targeted therapies for IAV and highlight their potential as diagnostic reagents. IMPORTANCE: Influenza A virus is one of the few viruses that can cause devastating pandemics. Due to the high mutation rates of this virus, annual vaccination is required, and antivirals are short-lived. Monoclonal antibodies present a promising approach to tackle influenza virus infections but are associated with some limitations. To improve on this strategy, we explored the Affimer platform, which are antibody-like proteins made in bacteria. By performing phage-display against a monomeric version of influenza virus fusion protein, an established viral target, we were able to isolate Affimers that inhibit influenza virus infection . We characterized the mechanism of inhibition of the Affimers by using assays targeting different stages of the viral replication cycle. We additionally characterized HA-Affimer complex structure, using a novel approach to prepare samples for cryo-electron microscopy. Overall, these results show that Affimers are a promising tool against influenza virus infection. |
 External links | mBio / PubMed:39037231 / PubMed Central |
| Methods | EM (single particle) |
| Resolution | 3.4 - 4.4 Å |
| Structure data | EMDB-17724, PDB-8pk3:  EMDB-17725: CryoEM reconstruction of Influenza A virus (HK68) hemagglutinin bound to an Affimer reagent  EMDB-18137: HK68 cryo-EM structure achieved via rapid-spray and vitrification for grid preparation |
| Chemicals |  ChemComp-NAG: |
| Source |
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 Keywords | ANTIVIRAL PROTEIN / Complex / Inhibitor / CryoEM / Antiviral |
influenza a virus