Notes on Genus: Marnavirus
Type member: Heterosigma akashiwo RNA virus
The genus is the only member of the family Marnaviridae
and currently consists of only one virus. Its genome features place it in the picorna-like superfamily but not within any of the currently recognised families. The virus infects a marine photosynthetic protist (Rhaphidophyte) and the name is derived from the Latin mare
(sea) and RNA (for the genome).
Virions isometric (icosahedral), not enveloped, about 25 nm in diameter.
Monopartite positive sense single-stranded RNA c.
8.5 kb in length, with a 3'-polyA tail.
Genus Genomic Organization
The RNA encodes a single polyprotein that is subsequently processed into the functional products. The major structural proteins are encoded near the C-terminus.
Type Member Genomic Organization
The genome of about 8,600 nucleotides is translated into a single polyprotein, which is subsequently processed into fuctional products. These have not been completely characterised but helicase, protease and RNA polymerase motifs have been identified in the N-terminal two thirds of the polyprotein and at least 2 structural proteins are at the C-terminus.