Influenza A Virus


Influenza A viruses are important pathogens that still rank among the significant global health problems. Seasonal strains of influenza virus are estimated to result in the death of over 50.000 people per year. As recently demonstrated by the outbreak of H1N1 swine-origin human influenza A (H1N1) virus in 2009, pandemic strains are capable of rapidly spreading around the world, infecting millions of people. The development of a vaccine against an emerging influenza strain requires up to one year and the efficiency of the existing antiviral agents is limited by the increasing viral resistance. Therefore, novel targets for drug development are urgently needed, which will be indentified by the detailed molecular elucidation of the multi-step viral replication cycle. The virions of the enveloped influenza viruses contain single-stranded negative-sense RNA encoding 11 proteins. While the structure and the function of some viral proteins are already known, particularly their specific interactions and the associated processes within the viral life cycle remain to be investigated. The interactions of the viral protein M1, which is supposed to play a key role in the replication process of the influenza virus, will be in the main focus of this project. According to the prevailing model of viral assembly, M1 is membrane associated, forming a matrix layer under the virion envelope by multiple protein-protein and lipid-M1 protein interactions. Particularly the investigation of the self-assembly and disassembly process of M1, the structural characterization of the M1-NS2 complex, and the analysis of specific interactions of M1 with lipid bilayers, are in the focus.
Crystallographic approaches failed so far due to the increased flexibility proposed for specific domains of full-length M1 and NS2. More promising is the application of scattering techniques in solution to gain insights into structural aspects of assembly and interactions of M1. Small-angle X-ray scattering (SAXS) is sometimes the only method able to characterize the structure of complex objects, although the resolution of the obtained data is restricted to the determination of the size and the shape of a biomolecule to date. However, this technique is non-destructive, does not require special sample preparation and allows to readily modify the environmental conditions of the sample including temperature, pressure, ionic strength, pH, and addition of active substances. A new BioSAXS beamline (P12) was recently commissioned at the novel third-generation synchrotron source PETRA 3 at DESY (Hamburg), which is supposed to push the limits of synchrotron SAXS technique based on the exceptional high brilliance of the produced X-rays. This technical innovation will be applied to obtain new insights into the assembly and interactions of the influenza A M1 protein on maximum spatial resolution, supplemented by the application of well-established standard techniques of biochemistry and structural biology. Moreover, these investigations will significantly contribute to the development of advanced experimental technologies on the high brilliance BioSAXS beamline, including the establishment and the validation of time-resolved SAXS experiments. This challenging technical objective of the project will be performed in close cooperation with project partners from the EMBL in Hamburg and the University of Moscow, Russia, and is suggested to provide initial information of the dynamic interactions of the M1 protein and its binding partners, which will contribute to a more comprehensive understanding of the replication cycle of the influenza A virus.

 

Contact person for this project: Jens Klingbeil