Expression and characterization of RNA-dependent RNA polymerase of Ectropis obliqua virus.

Replication of positive-strand RNA virus is mediated by a virus- encoded RNA-dependent RNA polymerase (RdRp). To study the replication of Ectropis obliqua virus (EoV), a newly identified insect virus belonging to the family Iflaviradae, we expressed the RNA polymerase domain in Escherichia coli and purified it on a Ni-chelating HisTrap affinity column. It is demonstrated that EoV RdRp initiated RNA synthesis in a primerand poly (A)-dependent manner in vitro. Furthermore, the effect of primer concentration, temperature, metal ions (Mg2+, Mn2+, and K+) on enzymatic activity were determined. Our study represented a first step towards understanding the mechanism of EoV replication.