Influenza A virus NS1 and PI3 Kinase: A structural investigation of their biological interaction

Influenza A viruses are responsible for serious human and animal diseases, causing seasonal outbreaks and, more rarely, worldwide pandemics, the ?swine flu? being the latest example. Influenza A viruses are relatively simple viruses, making only a few virus proteins. One of these proteins, termed NS1, is not essential for virus replication (growth) in the laboratory but is required for the virus to establish infections in people or animals. It has multiple functions, including counteracting the infected individuals (host) defences against viruses, and in promoting virus replication. To perform these functions the NS1 protein has to interact with many host cell proteins. The aim of this work is to further define how the NS1 protein performs these functions by determining the shape of the protein, defining which parts of NS1 are responsible for its binding to specific host cell proteins, and to better define what roles these different interactions play during the life cycle of the virus. Using the information gained from these studies may pave the way to development of novel anti-viral drugs (which would work by blocking the function(s) of NS1) and the improvement of vaccine design. Indeed, in collaboration with the MRC Technology, part of these proposals are concerned with developing and using screens to identify compounds that interact with NS1 and which have anti-viral activity that may be subsequently developed as anti-influenza virus drugs.

The non-structural (NS1) protein of influenza A viruses is a multifunctional protein with roles that include inhibiting innate intracellular anti-viral responses, including the interferon (IFN) response, and in modulating virus replication and host-cell physiology (reviewed in Hale et al. JGV, 89, 2359). Whilst much has been learnt about the molecular mechanisms by which NS1 performs many of its multiple functions, there is still much to be learnt, especially with regards relating function to its structure, and in using the information gained for the improvement of human and animal health through the development of novel anti-viral drugs and the design of improved vaccines. The influenza NS1 protein is comprised of a RNA-binding domain and an effector domain that are joined by a flexible linker. It is unclear how a protein of such relatively small size can interact with so many distinct binding partners to elicit such a diverse range of responses. In this proposal we will use reverse and forward genetics, molecular, biochemical and cellular approaches, and structural studies to further address important questions concerning the function and structure of this essential viral virulence factor. More specifically, we will better define how and why influenza A viruses activates PI3 kinase.