There are more than 250,000 influenza-related deaths each year. Of special concern are the influenza H1N1 and H5N1 strains, which harbor H1 and H5 hemagglutinin (HA) and present potential for future pandemic outbreaks. Current treatments include Tamiflu (oseltamivir) and Relenza (zanamivir), which target the membrane protein neuraminidase (NA). Unfortunately, resistance is increasing in circulating influenza strains. For example, the 2008-2009 H1N1 strain exhibited ~100% resistance against Tamiflu, and thus influenza may be considered as a drug-resistant pathogen. As a consequence, new targets in influenza are urgently needed. HA plays a critical role in influenza entry and thus it i an attractive and novel target for therapeutic intervention. In the first step of influenza entry, A binds to the cellular receptor, sialic acid. Subsequently, the virus enters the cell via receptor-mediated endocytosis. In the endosome, the resulting low pH triggers a large conformational change in HA, which subsequently causes the viral membrane to fuse with the endosomal membrane to allow escape from the endosome. Entry inhibitors could conceivably target either the receptor binding step (binding inhibitors) or the membrane fusion step (fusion inhibitors). In this project we will develop NMR-based screening methods of small molecule libraries to influenza H1 and H5 HA with the long-term goal of developing binding and fusion inhibitors.
The Specific Aims are: (1) discovery of chemical probes that bind to influenza H1 and H5 HA in the neutral pH conformation;(2) discovery of chemical probes that bind to influenza H1 and H5 HA in the low pH conformation;(3) identify the site of probe binding by NMR competition experiments. Importantly, the NMR methods could be exploited to identify and improve small molecule therapeutics, characterize probe-envelope interactions in whole virus, and be applied to other viruses such as Ebola, HIV and SARS-CoV.

Public Health Relevance

Hemagglutinin plays a critical role in the entry of influenza. This application is designed to develop NMR techniques to give new insights into hemagglutinin structure and function, which may be exploited for the development of novel drug therapies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21AI101676-01
Application #
8354992
Study Section
Macromolecular Structure and Function E Study Section (MSFE)
Program Officer
Krafft, Amy
Project Start
2012-07-01
Project End
2014-06-30
Budget Start
2012-07-01
Budget End
2013-06-30
Support Year
1
Fiscal Year
2012
Total Cost
$239,250
Indirect Cost
$89,250
Name
University of Illinois at Chicago
Department
Biochemistry
Type
Schools of Medicine
DUNS #
098987217
City
Chicago
State
IL
Country
United States
Zip Code
60612
Antanasijevic, Aleksandar; Ramirez, Benjamin; Caffrey, Michael (2014) Comparison of the sensitivities of WaterLOGSY and saturation transfer difference NMR experiments. J Biomol NMR 60:37-44
Antanasijevic, Aleksandar; Basu, Arnab; Bowlin, Terry L et al. (2014) Mutagenesis studies of the H5 influenza hemagglutinin stem loop region. J Biol Chem 289:22237-45
Basu, Arnab; Antanasijevic, Aleksandar; Wang, Minxiu et al. (2014) New small molecule entry inhibitors targeting hemagglutinin-mediated influenza a virus fusion. J Virol 88:1447-60