Existing flu treatments only work after the virus has infected the body. But what if a medication could stop the infection from happening in the first place? Researchers at Scripps Research and the Albert Einstein College of Medicine have created drug-like molecules that can do just that, by stopping the initial stage of influenza infection.
The drug-like inhibitors prevent the virus from entering the body’s respiratory cells by targeting hemagglutinin, a protein on the surface of type A influenza viruses. The results, which were published in the Proceedings of the National Academy of Sciences on May 16, 2024, represent a significant advancement in creating a drug that can stop influenza infection.
The goal is to target the initial stage of influenza infection as it is better to prevent infection from occurring in the first place. However, these molecules could also be used to stop the spread of the virus.
According to Ian Wilson, DPhil, the Hansen Professor of Structural Biology at Scripps Research, the inhibitors will need further testing and optimization before they can be considered as antivirals for humans. However, these molecules have the potential to help prevent and treat seasonal flu infections and may not need annual updating like vaccines. The researchers had previously found a small molecule, F0045(S), with some ability to bind and inhibit H1N1 type A influenza viruses. They started by creating a highDennis Wolan, PhD, a senior principal scientist at Genentech and former associate professor at Scripps Research, explains that they used a high-throughput hemagglutinin binding assay to quickly screen large libraries of small molecules and identified the lead compound F0045(S). The goal of the study was to improve the chemical structure of F0045(S) in order to create molecules with better drug-like properties and a more specific binding ability to the virus. The Wolan lab utilized “SuFEx click-chemistry,” developed by Nobel laureate K. Barry Sharpless, PhD, to generate a large lThe researchers created a library of candidate molecules with different modifications to the original structure of F0045(S). After screening the library, they found two molecules, 4(R) and 6(R), that had better binding affinity than F0045(S).
Wilson’s team then generated X-ray crystal structures of 4(R) and 6(R) when they were attached to the flu hemagglutinin protein. This allowed them to pinpoint the binding sites of the molecules, understand why they had better binding ability, and identify areas where they could make improvements.
“We demonstrated that these inhibitors bind much more tightly to the viral antigen hemagglutinin than the original F0045(S) structure,” said the researchers.Wilson stated that the original lead molecule had limitations in its ability to interact with influenza. By using click-chemistry, they were able to enhance the compounds’ effectiveness by targeting additional pockets on the antigen surface.
The researchers conducted tests on 4(R) and 6(R) in cell culture to confirm their antiviral properties and safety. They found that 6(R) was non-toxic and had over 200 times greater cellular antiviral potency compared to F0045(S).
Finally, the researchers utilized a targeted approach to optimize 6(R) and create compound 7, which demonstrated even greater antiviral effectiveness.
Wilson emphasized that compound 7 is the most potent small-molecule hemagglutin.the most potent inhibitor developed so far,” mentioned Seiya Kitamura, an author involved in the project while working at Scripps Research as a postdoctoral fellow and currently serving as an assistant professor at the Albert Einstein College of Medicine.
In upcoming research, the team aims to refine compound 7 and evaluate the inhibitor’s effectiveness in influenza animal models.
<p”Improving the molecule’s potency any further will be challenging, but there are numerous other factors to consider and enhance, such as pharmacokinetics, metabolism, and aqueous solubility,” explained Kitamura.
Given that the inhibitors in this study specifically target H1N1 influenza strains, scientists are also aiming to create similar drug-like inhibitors to target different influenza strains like H3N2 and H5N1. This research received support from the NIH, the Nathan Shock Institute of Aging Research, and Einstein-Montefiore.
