Mamastro virus

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Human astroviruses
Astrovirus.jpg

Human astroviruses under the electron microscope

Systematics
Classification : Viruses
Area : Riboviria
Empire : Orthornavirae
Phylum : Pisuviricota
Class : Stelpaviricetes
Order : Stellavirals
Family : Astroviridae
Genre : Mamastro virus
Taxonomic characteristics
Baltimore : Group 4
Symmetry : icosahedral
Cover : no
Left
NCBI  Taxonomy: 249588
ViralZone ( ExPASy , SIB): 281


The genus Mamastrovirus includes viruses of the Astroviridae family that infect Mammalia (mammals and, in particular, humans), which explains the origin of the name. As of November 2018, the International Committee on Taxonomy of Viruses (ICTV) confirmed 19 species ( Mamastrovirus 1 to 19 ) in this genus, divided into two genogroups GI and GII; Type species is the human pathogenic Mamastrovirus 1 (GI). Human pathogenic human astroviruses of this type species were described in humans for the first time in 1975 with the help of an electron microscopic identification in stool samples from an outbreak of diarrhea . In the meantime, several different virus species have been identified as human astroviruses (ie human pathogenic mamastroviruses): Mamastrovirus 6 (also GI) and Mamastrovirus 8 and 9 (both GII). In addition, very similar viruses could also be isolated from some other mammal species, which are also placed in the genus Mamastrovirus , with hosts among the cats (feline), pigs (porcine), sea lions, dogs (canine), dolphins, mink (musteline) , Sheep (ovine) and bats. Similar pathogens that occur in birds such as ducks, chickens and turkeys are listed as a second genus Avastrovirus with three species ( Avastrovirus 1 to 3 ) within the family Astroviridae .

The Astroviridae , like Caliciviridae and Picornaviridae, are non-enveloped , single-stranded RNA viruses with positive polarity .

illness

Human astroviruses have been described worldwide as the causative agent of gastroenteritis , especially in children but also in adults. The symptoms of infection are diarrhea , vomiting , fever, and abdominal pain. The illness lasts an average of 3 to 4 days, but is generally not a dangerous situation. In rare cases, dehydration can also occur. Infected people do not need inpatient treatment as the symptoms subside on their own after a short time.

diagnosis

Electron microscopy , ELISA , immunofluorescence and PCR can be used in the course of virus diagnostics to detect virions , antigens or viral RNA in the stool of infected people.

Epidemiology

A study in the UK that was published in 1999 found an inappropriateness of 3.8 per 1000 inhabitants per year, making astrovirus the fourth most common cause of viral gastroenteritis. Studies in the United States have found astroviruses in the stool of 2 to 9 percent of children with symptoms. The disease is most common in children under 2 years of age, but there have also been outbreaks in adults. Studies from Glasgow and the USA suggest that astrovirus infection is often symptom-free . In areas with temperate climates , astrovirus infections are more common in winter, while in the tropics, most infections occur in the rainy season. Astroviruses are transmitted through contaminated water or contaminated food.

Prevention

There is no vaccination or antiviral treatment for astroviruses, but personal hygiene can reduce the risk of infection .

Host spectrum

The previously known host spectrum (synonym tropism ) of the astroviruses includes humans, goats, cattle, sheep, pigs, deer, bats and sea lions.

construction

Astroviruses are non-enveloped icosahedral viruses with a diameter of 28 to 35 nm and a characteristic star-shaped surface structure that gives them their name and which is visible under an electron microscope.

Genome

The genome of the human astrovirus consists of a single RNA strand with positive polarity and has a poly-A tail at the 3 'end , but no 5' cap structure . Without the poly A tail, the astrovirus genome is 6.8-7.9 kbp long. It contains three open reading frames , with ORF1a and ORF1b overlapping by 70 bp. The third open reading frame is called ORF2. The mutation rate was determined to be 3.7 × 10 −3 nucleotide exchanges per site and year and a synonymous rate of change of 2.8 × 10 −3 nucleotide exchanges per site and year.

Systematics

According to ICTV (November 2018) and Donato / Vijaykrishna (2017), the system is as follows:

  • Genus Mamastrovirus
  • Genogroup GI
  • Species Mamastrovirus 1 ( human astrovirus GI-A , type species, GI.A-human)
  • Species Mamastrovirus 2 ( cat astrovirus , GI.B-feline)
  • Species Mamastrovirus 3 ( porcine astrovirus , GI.C-porcine)
  • Species Mamastrovirus 4 ( Sea Lion Astrovirus GI-D , GI.D-California sea lion)
  • Species Mamastrovirus 5 ( canine astrovirus , GI.E-canine)
  • Species Mamastrovirus 6 ( human astrovirus GI-F , GI.F-human)
  • Species Mamastrovirus 7 ( bottlenose dolphin astrovirus , GI.G-bottlenose dolphin)
  • Genogroup GII
  • Species Mamastrovirus 8 ( human astrovirus GII-A , GII.A-human)
  • Species Mamastrovirus 9 ( Human Astrovirus GII-B , GII.B-human)
  • Species Mamastrovirus 10 ( Mink Astrovirus , GII.C-mink)
  • Species Mamastrovirus 11 ( Sea Lion Astrovirus GII-D , GII.D-California sea lion)
  • Species Mamastrovirus 12 ( bat astrovirus GII-E , GII.E-bat)
  • Species Mamastrovirus 13 ( Sheep Astrovirus , GII.F-ovine)
  • Species Mamastrovirus 14 - 19 ( bat astrovirus GII-G to GII-L , GII.G-bat to GII.L-bat)

In addition to these officially recognized species, there are a number of other suggestions.

literature

Individual evidence

  1. ↑ ICTV Master Species List 2018b v2 MSL # 34v, March 2019
  2. ↑ a b c d ICTV: ICTV Master Species List 2019.v1 , New MSL including all taxa updates since the 2018b release, March 2020 (MSL # 35)
  3. ↑ SIB: Astroviridae , on: ViralZone
  4. ↑ a b Celeste Donato, Dhanasekaran Vijaykrishna: The Broad Host Range and Genetic Diversity of Mammalian and Avian Astroviruses , in: Viruses 2017, 9 (5), 102; doi: 10.3390 / v9050102 (Review)
  5. ^ DW Brown, KB Gunning, DM Henry, ZL Awdeh, JP Brinker, S. Tzipori, JE Herrmann: A DNA oligonucleotide microarray for detecting human astrovirus serotypes. In: J Virol Methods (2008), Vol. 147 (1), pp. 86-92. PMID 17905448 , PMC 2238180 (free full text).
  6. ↑ P. De Benedictis, S. Schultz-Cherry, A. Burnham, G. Cattoli: Astrovirus infections in humans and animals - molecular biology, genetic diversity, and interspecies transmissions. In: Infect Genet Evol. (2011), Vol. 11 (7), pp. 1529-44. PMID 21843659 .
  7. ↑ Madeley CR: Virus diarrhea in hospital . In: J. Hosp. Infect. . 12, No. 3, 1988, pp. 145-9. doi : 10.1016 / 0195-6701 (88) 90001-1 . PMID 2904454 .
  8. ^ Glass RI, Noel J, Mitchell D et al. : The changing epidemiology of astrovirus-associated gastroenteritis: a review . In: Arch. Virol. Suppl. . 12, 1996, pp. 287-300. PMID 9015126 .
  9. ^ NK Krishna: Identification of structural domains involved in astrovirus capsid biology. In: Viral Immunol. (2005), Vol. 18 (1), pp. 17-26. PMID 15802951 ; PMC 1393289 (free full text).
  10. ↑ Willcocks MM, Brown TD, Madeley CR, Carter MJ: The complete sequence of a human astrovirus . In: J. Gen. Virol. . 75 (pt 7), No. 7, 1994, pp. 1785-8. doi : 10.1099 / 0022-1317-75-7-1785 . PMID 8021608 .
  11. ↑ IV Babkin, AY Tikunov, EV Zhirakovskaia, SV Netesov, NV Tikunova: high evolutionary rate of human astrovirus. In: Infect Genet Evol. (2012), Vol. 12 (2), pp. 435-42. PMID 22326537 .
  12. ↑ ICTV : Master Species List 2018a v1 , MSL including all taxa updates since the 2017 release. Fall 2018 (MSL # 33)
  13. ↑ ICTV : Positive Sense RNA Viruses> Positive Sense RNA Viruses: Astroviridae , ICTV 9th Report (2011)