catalytic core domain of RNA-dependent RNA polymerase (RdRp) in the family Hepeviridae of positive-sense single-stranded RNA [(+)ssRNA] viruses
This group contains the catalytic core domain of RdRp of RNA viruses belonging to the family Hepeviridae, order Hepelivirales. The family Hepeviridae includes enterically transmitted small non-enveloped [(+)ssRNA viruses. It includes the genera Piscihepevirus, whose members infect fish, and Orthohepevirus, whose members infect mammals and birds. Members of the genus Orthohepevirus include hepatitis E virus, which is responsible for self-limiting acute hepatitis in humans and several mammalian species; the infection may become chronic in immunocompromised individuals. Avian hepatitis E virus causes hepatitis-splenomegaly syndrome in chickens. Hepeviridae genomes (approximately 7.2 kb) have 5' methyl G caps and 3' poly (A) tails, and contain three ORFS. They have two mRNAs, a genome length and a subgenomic mRNA: the genome-length mRNA is translated to produce proteins required for RNA replication while the subgenomic mRNA is used to produce the capsid protein. Some of the capsid protein is glycosylated, which is an unusual finding for an unenveloped virus. 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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