Characterization of the influenza virus polymerase using T-705 and ribavirin and design of RNA chain terminating prodrugs of these unique antiviral agents

The novel antiviral agent T-705 (favipiravir) and distantly related carboxamide compound ribavirin are both clinically used for the therapy of influenza virus infections. Mechanistically, both may act by inhibiting the viral RNA-dependent RNA polymerase or by causing lethal virus mutagenesis. In the first part of this project, I want to gain insight in the influenza virus polymerase complex, using T-705 and ribavirin as unique tools. Viruses carrying T-705- and ribavirin-associated mutations in the viral polymerase complex will be selected, and an in-depth analysis of the impact of these mutations on viral fitness and polymerase activity will be carried out. This will be done by a combination of cell culture and biochemical (enzymatic) studies. In the second part, I will evaluate the long-term toxic effects of T-705 and ribavirin. Their potential cytotoxic effects related to their RNA-mutagenic properties, will be studied in cell culture, by measuring cell proliferation and primary mitochondrial toxicity, as well as in enzymatic assays with the human mitochondrial RNA polymerase. Finally, in collaboration with medicinal chemists, I will design prodrugs derived from (ribo) monophosphorylated T-705 and ribavirin, in order to convert T-705 and ribavirin into obligate chain terminators. Antiviral evaluation of the synthesized compounds will help to further optimize the chemical structures. This may ultimately lead to a new concept of potent and safer anti-RNA virus agents.