Algal Marnaviruses (Marnaviridae)

The family Marnaviridae represents a group of positive-sense, single-stranded RNA viruses, falling within the order Picornavirales . They are mono- or dicistronic, have a polyadenylate tail and have conserved motifs for RNA helicase, RNA-dependent RNA polymerase (RdRp) and structural protein domains. This family previously contained a single representative species, Heterosigma akashiwo RNA virus , and genus, Marnavirus . However, it has recently undergone a major taxonomic revision and now includes 20 species within 7 genera. These 20 viruses include cultured representatives infecting single-celled eukaryote (protist) hosts while others are only known from marine RNA virus metagenomic studies, although these metagenomic viruses are also believed to infect protists.