RNA-dependent RNA polymerase which is found both free and covalently attached to the genomic RNA. May also contain guanylyl and methyl transferase activities (By similarity). a ribonucleoside 5'-triphosphate + RNA(n) = diphosphate + RNA(n+1) Interacts with VP3 in the cytoplasm. Minor amounts are incorporated in the virion. May exist in multiple phosphorylated forms.