FIG. 7.

Proposed model of HDV antigenomic RNA replication by RNAP II. Briefly, unphosphorylated SHDAg binds viral RNA through its RNA-binding domain and interacts with RNAP IIA at the initiation site to promote antigenomic RNA replication. At the preinitiation/initiation stage, the HDV antigenomic RNA replication complex is unphospho-enriched. The phosphorylation of SHDAg by a certain cellular kinase(s) stimulates the transition of viral antigenomic RNA replication from the initiation into the elongation complex, which is phospho-enriched.