Marnaviridae

Marnaviridae is a family of positive-stranded RNA viruses in the order Picornavirales. The first marnavirus that was isolated, and which is the type species for the family, infects a Microphyte: the toxic bloom-forming Raphidophyte, Heterosigma akashiwo. Algae therefore seem to serve as natural hosts. There is only one genus (Marnavirus) and one species in this family, the type species Heterosigma akashiwo RNA virus (HaRNAV). HaRNAV was isolated from water collected in the Strait of Georgia in British Columbia, Canada, from a concentrated virus assemblage using the host Heterosigma akashiwo (NEPCC 522). Although the International Committee on the Taxonomy of Viruses currently only recognizes one member of the family, environmental sequencing of the RNA-dependent RNA polymerase has shown that there are many related viruses in the sea that show a high degree of temporal and spatial diversity. Viruses in Marnaviridae are non-enveloped, with icosahedral geometries, and T=pseudo3 symmetry. The diameter is around 25 nm. Genomes are linear and non-segmented, around 8.6kb in length.