NS1; influenza; signaling; virus; PI3K; phosphorylation; proteomics; immunity; virulence
Turkington Hannah L., Juozapaitis Mindaugas, Tsolakos Nikos, Corrales-Aguilar Eugenia, Schwemmle Martin, Hale Benjamin G. (2018), Unexpected Functional Divergence of Bat Influenza Virus NS1 Proteins, in Journal of Virology
, 92(5), e02097-17-e02097-17.
Lopes Antonio M., Domingues Patricia, Zell Roland, Hale Benjamin G. (2017), Structure-Guided Functional Annotation of the Influenza A Virus NS1 Protein Reveals Dynamic Evolution of the p85beta-Binding Site during Circulation in Humans, in JOURNAL OF VIROLOGY
, 91(21), e01081-17.
Patzina Corinna, Botting Catherine H., Garcia-Sastre Adolfo, Randall Richard E., Hale Benjamin G. (2017), Human Interactome of the Influenza B Virus NS1 Protein, in JOURNAL OF GENERAL VIROLOGY
, 98(9), 2267-2273.
Turkington Hannah L., Juozapaitis Mindaugas, Kerry Philip S., Aydillo Teresa, Ayllon Juan, García-Sastre Adolfo, Schwemmle Martin, Hale Benjamin G. (2015), Novel Bat Influenza Virus NS1 Proteins Bind Double-Stranded RNA and Antagonize Host Innate Immunity, in Journal of Virology
, 89(20), 10696-10701.
Influenza viruses generate a high human and animal disease burden with significant economic consequences. Zoonotic transmission of influenza viruses from animal reservoirs continually threatens to cause severe human outbreaks, and such spillovers can act as precursors to pandemics. A feature of influenza virus strains is their variability in disease causing potential, of which virus-encoded virulence factors play a major role. Thus, defining key viral genomic sequences associated with pathogenicity is essential for surveillance efforts to identify and eliminate viruses of concern before they infect humans. Understanding the fundamental molecular mechanisms underlying the interaction of viral virulence factors with host-cells may also suggest new targets for therapeutic strategies to limit disease.Our research focuses on the multifunctional influenza virus NS1 virulence factor, which exquisitely re-wires host signaling cascades in the infected cell. A major function of NS1 is to disable host innate immune defenses, a process achieved by multiple well-established mechanisms that vary in efficiency between strains and impact pathogenicity. NS1 also binds and activates the p85ß subunit of human phosphoinositide 3-kinase (PI3K), a host lipid kinase implicated in regulating cell growth, metabolism and survival. This interaction is important for virus replication and virulence, and recent studies have highlighted strain-dependent effects of this event on influenza disease in animal models. Nevertheless, the precise molecular mechanisms and cell biological consequences of NS1 binding p85ß remain to be determined. Furthermore, although broad-spectrum PI3K inhibitors have been proposed as new host-targeted antivirals, there are indications that efficacy may be NS1-genotype dependent. Thus, a thorough understanding of the interplay between NS1 and host p85ß is essential.In preliminary work, we have used a structure-guided alanine-scanning approach to comprehensively identify the ‘molecular footprint’ of the NS1:p85ß interaction. Furthermore, by assessing polymorphisms in NS1 at this site, we have identified several amino-acid substitutions that specifically destabilize or enhance p85ß-binding, suggesting unexplored natural diversity in this NS1 function. Here, we will:Aim A1. Generate influenza viruses expressing NS1 proteins with amino-acid substitutions causing p85ß-binding variation, and characterize the ability of each virus to activate PI3K and replicate efficiently.Aim A2. Determine if phenotypes of the mutant viruses can be compensated by heterologous PI3K, and if so use specific PI3K activating mechanisms to understand those most relevant to influenza viruses.Aim A3. Assess potential roles for NS1-activated PI3K in antagonizing host antiviral stress responses.Aim B. Combine the newly developed viral tools with state-of-the-art quantitative phospho-proteomics to understand the cell signaling consequences of NS1-mediated PI3K activation in an unbiased manner.Our fundamental studies should help elucidate the impact of newly identified strain variation on influenza virus NS1 virulence factor function. By studying these variants with both rational and unbiased approaches, we will reveal the basic molecular mechanisms and biological consequences underlying NS1 hijack of host PI3K. This knowledge will provide a framework for understanding influenza disease markers and virulence determinants, and could provide novel perspectives on basic cell biology systems.