Hepeviridae

from Wikipedia, the free encyclopedia
Hepeviridae
Hepatitis E virus.jpg

Hepatitis E virus virions in the TEM

Systematics
Classification : Viruses
Area : Riboviria
Empire : Orthornavirae
Phylum : Kitrinoviricota
Class : Alsuviricetes
Order : Hepelivirales
Family : Hepeviridae
Taxonomic characteristics
Genome : (+) ss RNA linear
Baltimore : Group 4
Symmetry : icosahedral
Cover : no
Scientific name
Hepeviridae
Left
NCBI  Taxonomy: 291484
ViralZone ( ExPASy , SIB): 714

The Hepeviridae are non-enveloped viruses with a single-stranded, linear RNA with positive polarity . As of November 2018, the family comprises two genera recognized by the International Committee on Taxonomy of Viruses , Piscihepevirus (new) and Orthohepevirus (previously simply Hepevirus , originally assigned to the Caliciviridae family as hepatitis E-like viruses - the Hepeviridae family was only introduced taxonomically in 2006 ). The prototype of the family is the human pathogenic Orthohepevirus A ( hepatitis E virus , HEV).

construction

The viruses of the Hepeviridae family are icosahedral or spherical, not enveloped. The virus particles of the Hepeviridae appear in the TEM to be about 27 to 34 nm in diameter. The particles are unencapsulated capsids with probably icosahedral symmetry. The main component of the capsid is the main core protein CP (72  kDa ) , which is probably only cleaved by proteases before the capsids are assembled. Antibodies against another structural protein 1.5 kDa in size were found in infected hosts. The function of this protein is unknown. The morphology of the particles established the proximity to the Caliciviridae .

The RNA genome of the Hepeviridae is linear and not segmented with a length of about 7200  nucleotides . It is divided into three open reading frames arranged (ORFs), wherein the first non-structural proteins with the viral polymerase, helicase, protease, and replicative proteins encoded . ORF 2 codes for the main core protein CP. The ORF 2 partially overlaps the ORF 3, which codes for a phosphoprotein of unknown function. The ORF1 protein appears to be related to members of the Alphatetraviridae , while the capsid protein is related to that of the Astrovirus (family Astroviridae ). This suggests that at some point in the past a recombination event between at least two different viruses has created the ancestors of this family that is the cause of the linkage of structural and non-structural proteins.

Biological properties

Orthohepevirus A (HEV), which is pathogenic to humans, is the causative agent of a form of faecal - orally transmitted hepatitis , which occurs sporadically or in larger outbreaks, especially during floods in Southeast Asia. Antibodies against HEV could be found in many animals, so that the suspicion of an infection transmitted from animals to humans ( zoonosis ) was expressed. However, there are z. B. in pigs and birds own isolates of the virus, which can be clearly distinguished from the human subtypes. The subtype HEV-3 could be transferred experimentally from pigs to primates .

Systematics

Internal system

The following structure of the Hepeviridae follows the requirements of the International Committee on Taxonomy of Viruses (ICTV) as of November 2018, supplemented by subtypes.

  • Family Hepeviridae
  • Genus Orthohepevirus (outdated Hepevirus , Hepatitis-E-like viruses )
Hepatitis viruses pathogenic to humans (hosts: humans, including primates such as rhesus monkeys)
  • Subtype hepatitis E virus 1 (HEV-1, genotype 1a, Burma ( Myanmar ), China )
  • Subtype hepatitis E virus 2 (HEV-2, genotype 2a, Mexico)
  • Subtype Hepatitis E Virus Isolate Pakistan
  • Subtype hepatitis E virus isolate rhesus
Porcine hepatitis viruses (PHEV, hosts: domestic pigs and wild boars):
  • Subtype Hepatitis E virus 3 (alias Swine hepatitis E virus , HEV-3, genotype 3a, Meng)
  • Subtype Hepatitis E virus 3 (alias Swine hepatitis E virus , HEV-4, genotype 4a)
  • Subtype Wild boar hepatitis E virus genotype 5a
  • Subtype Wild boar hepatitis E virus genotype 6a
Camelid hepatitis viruses (hosts: camels):
  • Subtype Camel hepatitis E virus genotype 7a
  • Subtype Camel hepatitis E virus genotype 8a
  • Species Orthohepevirus C
  • Subtypes Rat hepatitis E virus (affects rats)
  • Subtypes Ferret hepatitis E virus (attacks Mustela putorius : Waldiltisse / ferret)
  • Species Orthohepevirus D
  • Subtypes Bat hepatitis E virus (attacks bats)
  • Genus Piscihepevirus
  • Genus ' Insecthepivirus ' (suggested)
  • Species ' Sogatella furcifera hepe-like virus ' (proposed)

External system

In 2015, Koonin et al taxonomically assigned the Hepeviridae (due to their relationship) to the supergroup 'Alphavirus-like superfamily' they postulated. The sister group is thereafter the family Togaviridae . The members of this proposed supergroup belong to different groups of the Baltimore classification , usually they are single-stranded RNA viruses of positive polarity ((+) ssRNA, Baltimore group 4), but there are also double-stranded representatives (marked with dsRNA, Find Baltimore Group 3).

This suggestion has now been replaced by the ICTV Master Species List # 35 of March 2020. A comparison of the cladograms can be found in Tymovirales §ICTV Master Species List # 35 .

Individual evidence

  1. ↑ ICTV Master Species List 2018b v1 MSL # 34, Feb. 2019
  2. ↑ a b c d e ICTV: ICTV Master Species List 2019.v1 , New MSL including all taxa updates since the 2018b release, March 2020 (MSL # 35)
  3. ↑ GC Schlauder, IK Mushahwar: Genetic heterogeneity of Hepatitis E virus Journal of Medical Virology 2001, 65, PMID 11536234 , pp. 282-292
  4. ^ Andrew G Kelly, Natalie E Netzler, Peter A White: Ancient recombination events and the origins of hepatitis E virus . In: BMC Evolutionary Biology . 16, No. 1, 2016, p. 210. doi : 10.1186 / s12862-016-0785-y . PMID 27733122 . PMC 5062859 (free full text).
  5. ↑ X.-J. Meng: Novel strains of Hepatitis E virus identified from humans and other animal species: is hepatitis E a zoonosis? Journal of Hepatology 2000, 33, PMID 11097496 , pp. 842-845
  6. ↑ ICTV : Master Species List 2018a v1 , MSL (# 33) including all taxa updates since the 2017 release. Fall 2018
  7. ↑ Positive-sense RNA Viruses> Hepeviridae: Genus: Orthohepevirus , on: ICTV online
  8. ↑ Baoyuan Liu et al. : Avian hepatitis E virus infection of duck, goose, and rabbit in northwest China , in: Nature> Emerging Microbes & Infections, Volume 7, 76, May 2, 2018, doi: 10.1038 / s41426-018-0075-4
  9. ↑ a b Nan Wu, Peipei Zhang, Wenwen Liu, Xifeng Wang: Sogatella furcifera hepe-like virus: First member of a novel hepeviridae clade identified in an insect . In: Virus Research . 250, 2018, pp. 81-86. doi : 10.1016 / j.virusres.2018.03.018 . PMID 29605729 .
  10. ↑ Since this group (referred to by the authors as English superfamily ) contains an order with the Tymovirales , their rank must be higher than this and should not be understood as a superfamily . Ranks higher than order were not given by the ICTV at the time of the work.
  11. ^ Eugene V. Koonin, Valerian V. Dolja, Mart Krupovic: Origins and evolution of viruses of eukaryotes: The ultimate modularity , in: Virology from May 2015; 479-480. 2-25, Epub March 12, 2015, PMC 5898234 (free full text), PMID 25771806

literature

Web links