title: Orthohepevirus
text: # Orthohepevirus
  
  Orthohepevirus is a genus of viruses assigned to the family Hepeviridae. Orthohepevirus is a fairly isolated viral genus in which the virions are characterized by round, non-enveloped and isometric capsids with a diameter of 27–34 nm. The hepatitis E virus belongs this genus as the species Orthohepevirus A
  
  ## Genome
  
  Orthohepeviruses have RNA genomes of 7176 nucleotides in length and infect vertebrates. Additionally, the genome is monopartite, linear, and single-stranded. The genome is 5' capped with a poly A tail at the 3' end. The genome possesses three main open reading frames. The first encodes non-structural proteins, the second encodes the capsid proteins, and the third encodes a small, multifunctional protein.
  
  ## Taxonomy
  
  Viruses from this genus have been isolated from a variety of mammals (including rodents, mustelids and bats) as well as birds. At least three variants of avian hepatitis E virus have been isolated from birds.
  
  A Hepatitis E-like virus has been isolated from a Swedish moose. This virus is quite distinct from the other known Hepatitis E viruses.
  
  In total, the genus has four recognized species: Orthohepevirus A, Orthohepevirus B, which was previously known as the avian hepatitis E virus, Orthohepevirus C, and Orthohepevirus D.
  
  ## History
  
  Hepatitis E was first isolated in 1990. It was thought to be restricted to humans until 1997 when it was isolated from pigs. The first isolation from birds was in 2001.
  
  ## Evolution
  
  One study has suggested that this species may have originated in birds and then spread to bats and other mammalian species.
  
  