catalytic core domain of RNA-dependent RNA polymerase (RdRp) in the family Nodaviridae of positive-sense single-stranded RNA [(+)ssRNA] viruses
This group contains the catalytic core domain of RdRp of RNA viruses belonging to the family Nodaviridae, order Nodamuvirales. The family name Nodaviridae, derives from the Japanese village of Nodamura where Nodamura virus was first isolated from Culex tritaeniorhynchus mosquitoes. Virions are non-enveloped and spherical in shape with icosahedral symmetry and diameters ranging from 25 to 33 nm. The members of the two genera in this family infect insects (Alphanodavirus) or fish (Betanodavirus). Alphanodavirus infection results in the stunting, paralysis and death of the insect host. The infection of fish by betanodaviruses such as striped jack nervous necrosis virus or red-spotted grouper nervous necrosis virus causes neural necrosis, encephalopathy or retinopathy and is associated with behavioral abnormalities and high mortality, posing significant problems for marine aquaculture. The genome consists of two molecules of (+)ssRNA: RNA1 and RNA2. The RdRp domain displays a right hand with three functional subdomains, called fingers, palm, and thumb. All RdRps contain conserved polymerase motifs (A-G), located in the palm (A-E motifs) and finger (F-G) subdomains. All these motifs have been implicated in RdRp fidelity such as processes of correct incorporation and reorganization of nucleotides.
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