Viral influenza, particularly the H5N1 strain of influenza A virus, is a serious threat to human health. Currently there are two different classes of approved anti-influenza drugs, which target different viral proteins: amantadine targets a protein called the M2 proton channel, while Tamiflu (oseltamivir) targets neuraminidase. In the last flu season, most strains of the influenza virus (including H5N1) have become resistant to the amantadine class of drugs, causing the CDC to issue a recommendation to discontinue their use. Thus, there is an urgent need for a second-generation amantadine-like drug that will be useful prophylactically against new mutant strains of the virus including H5N1. We will take a variety of approaches to design second generation M2 blockers. To accomplish this goal a team of investigators has been assembled (DeGrado, Cristian, Diamond, Klein, Lamb, Paessler, Pinto, Winkler), each with special expertise. This team, led by DeGrado, will build on important preliminary results to design second generation M2 blockers. To this end, we have crystallized the proton channel, both in the presence and absence of amantadine, and the structures will be solved in Aim 1. The availability of crystal structures of the protein will be used in structure-based drug design in Aim 2. In parallel, state-of-the-art high throughput screening methodologies will be employed to discover novel lead inhibitors (Aim 3). The in vitro potency of the lead compounds will be optimized in Aim 4. The goal of Aims 5 and 6 is to identify compounds or compound classes that demonstrate antiviral in vivo efficacy against M2 without obvious toxicity. These studies will evaluate acute toxicity, pharmacokinetic properties, metabolic stability and in vivo efficacy of the discovery lead compounds. The results from these studies will be used to select a few lead compounds for more complete drug development evaluations suitable for regulatory submission (Aims 7, 8). The ultimate goal of the program is to complete all studies to enable filing an IND. In addition to overseeing the overall program, DeGrado's group will be responsible for structural biology and the chemical aspects of the project.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project--Cooperative Agreements (U01)
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Special Emphasis Panel (ZAI1-TP-M (J2))
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Krafft, Amy
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University of Pennsylvania
Schools of Medicine
United States
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Li, Fang; Ma, Chunlong; DeGrado, William F et al. (2016) Discovery of Highly Potent Inhibitors Targeting the Predominant Drug-Resistant S31N Mutant of the Influenza A Virus M2 Proton Channel. J Med Chem 59:1207-16
Wu, Yibing; Canturk, Belgin; Jo, Hyunil et al. (2014) Flipping in the pore: discovery of dual inhibitors that bind in different orientations to the wild-type versus the amantadine-resistant S31N mutant of the influenza A virus M2 proton channel. J Am Chem Soc 136:17987-95
Polishchuk, Alexei L; Cristian, Lidia; Pinto, Lawrence H et al. (2014) Mechanistic insights from functional characterization of an unnatural His37 mutant of the influenza A/M2 protein. Biochim Biophys Acta 1838:1082-7
Williams, Jonathan K; Tietze, Daniel; Wang, Jun et al. (2013) Drug-induced conformational and dynamical changes of the S31N mutant of the influenza M2 proton channel investigated by solid-state NMR. J Am Chem Soc 135:9885-97
Mao, Lili; Wang, Jun; DeGrado, William F et al. (2013) An assay suitable for high throughput screening of anti-influenza drugs. PLoS One 8:e54070
Schmidt, Nathan W; Mishra, Abhijit; Wang, Jun et al. (2013) Influenza virus A M2 protein generates negative Gaussian membrane curvature necessary for budding and scission. J Am Chem Soc 135:13710-9
Ma, Chunlong; Fiorin, Giacomo; Carnevale, Vincenzo et al. (2013) Asp44 stabilizes the Trp41 gate of the M2 proton channel of influenza A virus. Structure 21:2033-41
Bankura, Arindam; Klein, Michael L; Carnevale, Vincenzo (2013) Proton affinity of the histidine-tryptophan cluster motif from the influenza A virus from ab initio molecular dynamics. Chem Phys 422:156-164
Dong, Hao; Fiorin, Giacomo; Degrado, William F et al. (2013) Exploring Histidine Conformations in the M2 Channel Lumen of the Influenza A Virus at Neutral pH via Molecular Simulations. J Phys Chem Lett 4:3067-3071
Wang, Jizhou; Ma, Chunlong; Wang, Jun et al. (2013) Discovery of novel dual inhibitors of the wild-type and the most prevalent drug-resistant mutant, S31N, of the M2 proton channel from influenza A virus. J Med Chem 56:2804-12

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