Capsid protein self-assembles to form an icosahedral capsid with a T=3 symmetry, about 32-35 nm in diameter, and consisting of 180 capsid proteins. Also acts as a suppressor of RNA-mediated gene silencing known as post-transcriptional gene silencing (PTGS), a mechanism of plant viral defense that limits the accumulation of viral RNAs. May suppress other innate immunity by binding to host TIP protein, thereby preventing it to migrate in the nucleus where it could trigger an antiviral response (PubMed:11041886, PubMed:24418554). Binds Ca(2+). Ca(2+) probably promotes virus assembly and stabilize the virus particle. Homodimer. Homomultimer. Interacts (via GW motifs) with Arabidopsis thaliana AGO1 and AGO4; these interactions inhibit RNA silencing ability of host AGOs. Interacts with host TIP (PubMed:15629774). Belongs to the icosahedral plant coat protein family.