Abstract
Mosquito- and tick-borne pathogens including Chikungunya, Dengue, Japanese encephalitis, West Nile, Yellow fever and Zika virus, represent a new economic and public health challenge. In the absence of effective vaccines and specific therapies, only supportive regimens are administrated for most of these infections. Thus, the development of a targeted therapy is mandatory to stop the rapid progression of these pathogens and preoccupant associated burdens such as Guillain-Barre syndrome, microcephaly. For this, it is essential to develop biochemical tools to help study and target key viral enzymes involved in replication such as helicase complexes, methyl-transferases and RNA-dependent RNA polymerases. Here, we show that a highly purified ZIKV polymerase domain is active in vitro. Importantly, we show that this isolated domain is capable of de novo synthesis of the viral genome and efficient elongation without terminal nucleotide transferase activity. Altogether, this isolated polymerase domain will be a precious tool to screen and optimize specific nucleoside and non-nucleoside inhibitors to fight against Zika infections.
Highlights
Zika virus (ZIKV) is a mosquito-borne member of the genus flavivirus within the Flaviviridae family
We found that the RNA-dependent RNA polymerase (RdRp) domain is active in the absence of the methyl-transferase domain (MTase) domain and is capable of de novo synthesis that was not limited to terminal nucleotide transferase activity using both homopolymers and specific RNA templates mimicking the natural viral UTR substrate
Based on previous studies on the MTase domain of West Nile virus[15], we used the cleavage site sequence GLVKRR/GG described between NS4 and NS5 to define the ZIKV NS5 N-terminus
Summary
Zika virus (ZIKV) is a mosquito-borne member of the genus flavivirus within the Flaviviridae family. In countries where Zika infection is present, an unexpected increase of GBS has been observed. Research on Zika has been focusing on developing diagnostic tests, setting of working cellular models of ZIKV and bio-physic approaches on certain viral proteins such as the NS2B-NS3 helicase complex[7] or the MTase domain of NS58. Recently Hercik et al described the purification of a ZIKV full-length NS5 protein (MTase and RdRp domains)[10]. We found that the RdRp domain is active in the absence of the MTase domain and is capable of de novo synthesis that was not limited to terminal nucleotide transferase activity using both homopolymers and specific RNA templates mimicking the natural viral UTR substrate. Since the original submission of this work, several new studies have been published on ZIKV RdRp purification and inhibition that corroborates our results[11,12,13,14]
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