Investigation of the Role of Interaction between Influenza a Virus Pa and Mitochondrial Proteins in Regulating Mitochondrial Functions, Mitochondrion-Mediated Innate Immune Response, and Viral Pathogenicity

Influenza A virus could cause pandemics and threat public health. Infection of the virus may result in severe respiratory complications in human. Interaction between the viral proteins and host factors is highly correlated with viral replication and pathogenicity. Previous studies have shown that the viral PA protein, which is a subunit of influenza viral polymerase and contains endonuclease activity, is involved in determination of virulence during influenza A virus infection. To further investigate the role of the PA protein in regulation of host biological processes, which may cause pathogenicity during influenza A virus infection, we have applied immunoprecipitation and proteomic approach to explore host proteins that interact with PA protein encoded by influenza A virus H1N1, pandemic H1N1, H3N2 and H7N9 subtypes, respectively. Our preliminary results and analyses highlighted that around 30% of the identified PA-interacting host proteins are mitochondrial proteins. In addition, we found that the PA protein is partly located in mitochondria, and that overexpression of the PA protein affects the mitochondrial respiration. Moreover, our study demonstrated that the PA protein could suppress the expression of type I and III interferons initiated by the RNA with 5’ triphosphate. These results imply that PA protein of influenza A virus not only serves as a subunit of viral polymerase, but may also interfere with mitochondrial functions and mitochondrion-mediated antiviral innate immunity. Therefore, we hypothesize that influenza A viral PA protein interacts with mitochondrial proteins, such as PYCR2 and NDUFS7, and affects mitochondrial functions and subsequently dysregulates host antiviral innate immune response to facilitate viral replication and cause pathogenicity. In this grant proposal, we intend to investigate the role of PA protein of influenza A virus in regulation of mitochondrial functions and to determine whether the PA protein attenuates mitochondrial functions to suppress host antiviral innate immune response during influenza A virus infection. The results obtained from this research will evidence that influenza PA-induced virulence is due to not only its endonuclease/polymerase activity but also dysregulation of mitochondrial functions and mitochondrion-mediated antiviral response. Since the endonuclease activity of influenza PA protein has been used as a target to develop new generation of antivirals against influenza viruses, the novel concept obtained in this research will be applied to advance the antiviral drugs targeting on PA protein. Collectively, the main goals of this proposal are summarized and specifically described as the following: Specific aim 1: To determine the role of PA protein of influenza A virus in regulation of mitochondrial functions, membrane potential, and antiviral immune response.Specific aim 2: To investigate the impact of the interaction between PA and mitochondrial proteins in interfering with mitochondrial functions and mitochondrion-mediated antiviral innate immune response.Specific aim 3: To determine whether the interaction between PA and mitochondrial proteins is involved in pathogenicity in vitro and in vivo during influenza A virus infection.

Project ID:PC10907-1515
External Project ID:MOST109-2320-B182-030-MY3