ISG15 fighting viral heart disease

• Antragstellerin: Professorin Dr. Antje Beling
• Fachliche Zuordnung: Virologie
• Förderung: Förderung von 2014 bis 2017
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 256633380

A robust innate immune response is essential to offend viral infection. Type I Interferons induce antiviral pathways both improving cardiac function and long-term survival in CoxsackievirusB3 (CVB3)-myocarditis. This project studies the function of the ubiquitin-like modifier Interferon-Stimulated Gene 15 kDa (ISG15) in the pathogenesis of acute myocarditis and its long-term sequel inflammatory cardiomyopathy in mice. Protein modification with ISG15 was identified to act as a critical innate response mechanism in cardiomyocytes to fight the battle against CVB3. Both ISG15-/- and ISG15-E1-activating enzyme Ube1L-/- mice displayed detrimental cardiac injury with impairment of cardiac function and mortality that was attributed to highly replicating CVB3 during acute myocarditis. Induction of ISG15 during acute disease prevented the development of chronic myocarditis. The major aim of this proposal is to determine molecular mechanisms how the ISG15-conjugation machinery functions against CVB3 infection. Several reports demonstrated antiviral effects of ISG15 that were attributed to ISG15-modification of viral proteins. Our preliminary data point towards ISG15-modification of CVB3 2A protease and 3D polymerase. We shall utilize epitope-tagged ISG15 in cell culture experiments to perform immunoprecipitations and affinity-purification studies combined with mass spectroscopy to define actual targets of the ISG15-system within the CVB3 proteome. Lysine-scanning approaches will be carried out to map ISG15-modification sites within the distinct CVB3 proteins. To provide evidence that ISG15-conjugation of viral proteins affects viral titers in CVB3-myocarditis, reverse genetic studies are planned. CVB3 K-to-R point mutants shall be generated and infection studies will be performed in vivo. We shall determine how the ISG15-system modulates host-pathogen interactions and thereby takes action in the battle against CVB3-infection. In addition to the direct cytopathic effects that are exerted by CVB3, the invasion of immune cells contributes to organ failure during acute myocarditis. ISG15-conjugation-deficient mice were characterized by increased numbers of immune cells in CVB3-infected hearts with macrophages representing the predominant cell type. Given that ISG15 is known to regulate macrophage functionality against viral infection, we aim to study the role of ISG15 in the regulation of macrophage function in CVB3 infection. Bone marrow chimera shall be generated from ISG15-/-, Ube1L-/- and wt mice and CVB3 myocarditis shall be monitored in these chimeras. We shall test whether ISG15-dependent processes in macrophages additionally contribute to the antiviral effects of ISG15 in CVB3-infection. In conclusion, this project shall elucidate mechanisms how interference with the ISG15-modification apparatus may attenuate disease progression in viral cardiomyopathy.

• DFG-Verfahren: Sachbeihilfen