Flu Fighters: High-Throughput Screening Uncovers New Influenza A Inhibitors

200,000 Compounds Screened, 3 Novel Drug Scaffolds Identified, and Deep Learning on the Horizon

Birmingham, AL – As seasonal and pandemic influenza strains continue to threaten public health worldwide, a team of researchers at Southern Research and the University of Alabama at Birmingham has completed a major milestone in antiviral discovery: screening a massive chemical library of 200,000 compounds using a high-throughput, cell-based immunofluorescence assay. The study, published in Antiviral Research (IF = 7.6), not only identified three novel chemical scaffolds with potent anti-influenza activity, but also laid the groundwork for deep learning–based drug discovery powered by the resulting 200,000+ data points.

🧾 Read the article here: https://doi.org/10.1016/j.antiviral.2025.106209

Discovery Highlights

Using a duplex immunofluorescence assay, the team measured both viral inhibition and cytotoxicity in the same well. The screening campaign against the H3N2 strain A/Udorn/72 yielded:

• 1,735 initial hits showing ≥54% virus inhibition

• 161 confirmed hits with favorable cytotoxicity profiles

• 3 major structural clusters (including thiadiazole and imidazoazepine scaffolds)

• 3 lead candidates (SRI-44211, SRI-44215, SRI-44221) with high potency against the pandemic H1N1 strain A/California/07/09

Impact & Next Steps

What sets this effort apart is not just the scale, but its translation potential:

• 🧠 200,000 data points generated will fuel a deep learning model now under development for virtual screening.

• 💥 The lead compounds showed IC₅₀ values <1 µM and selectivity indices up to 252 for A/Ca/07/09.

• 🧬 The screening framework supports rapid adaptation to emerging strains by swapping out antibodies for other subtypes.

A library of 200,000 compounds was screened using the influenza immunofluorescence assay, from which 191,384 valid antiviral results were obtained. From them, 1,735 met the cut-off criteria of 54 % inhibition or higher, and viability data was available for 1,545. The top 640 compounds based on percentage of inhibition were tested in the concentration-response confirmation antiviral and cytotoxicity assays. The selected set of 640 included a subset of 184 compounds with no cytotoxicity data. One-hundred and sixty-one compounds with low or no cytotoxicity were confirmed as active against the screen strain.

Behind the Scenes

This work is supported by NIH grant U19 AI142759. The full list of authors includes Yohanka Martinez-Gzegozewsk , Lynn Rasmussen, N. Miranda Nebane, Sara McKellip, Dee Radzieta, Anna Manuvakhova, Andrew J. Reece, Pedro Ruiz, Sixue Zhang , Omar Moukha-Chafiq, Melinda Sosa, Corinne Augelli-Szafran, Richard Whitley, Robert Bostwick, Paige Vinson.

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