Enzymatic Characterization of the Zika Virus RNA-Dependent RNA Polymerase, NS5
The relevance of Zika virus (ZIKV) to public health quickly became apparent after its epidemic in the Americas. This outbreak has raised its presence to over 60 countries and has revealed the role of Zika as a neuropathological agent, with the emergence of congenital microcephaly when women are infected during pregnancy and Guillian-Barre Syndrome in adults. In 2016 the WHO declared ZIKV a Public Health Emergency of International Concern. Currently, there is no vaccine for ZIKV, and the infection can be spread rapidly by mosquito vector as well as by sexual contact. Therefore, the development of antivirals is urgently needed. Structural and mechanistic studies of the viral components are paramount to the development of such antivirals.
An attractive target for ZIKV is the RNA-dependent RNA polymerase (RdRp), NS5. It replicates the ZIKV genome through its RdRp domain, stabilizes the newly synthesized genome through its methyltransferase domain by capping the RNA, as well as immunosuppression of the host antiviral defense. Enzymatic studies and structural analysis provide an understanding of the mechanisms of this enzyme, which facilitate the development of antiviral drugs. To this end, I have optimized reaction conditions for NS5 in vitro. Interestingly, this enzyme prefers Mn2+ instead of Mg2+ for full-length extension of RNA primers. To further my investigation of NS5, enzyme kinetic assays including steady-state and pre-steady state kinetics will be conducted to characterize the efficiency and fidelity of this enzyme to allow comparison to other important viral RdRps such as that from Hepatitis C.