Binds double-strand RNA (dsRNA) with high affinity. Suppresses the host RNA silencing-based antiviral response. Homodimer. Expressed at high levels early in the viral replication cycle. The dsRNA-binding region is required for suppression of RNA silencing. Encoded on a subgenomic RNA (RNA3) synthesized during replication and which is co-terminal with RNA1. Belongs to the nodaviridae B2 protein family.