''Parechovirus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

viruses A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1 ...

in the family ''

Picornaviridae Picornaviruses are a group of related nonenveloped RNA viruses which infect vertebrates including fish, mammals, and birds. They are viruses that represent a large family of small, positive-sense, single-stranded RNA viruses with a 30 nm i ...

''. Humans, ferrets, and various rodents serve as natural hosts. The genus currently consists of six accepted species. Human parechoviruses may cause gastrointestinal or respiratory illness in infants, and they have been implicated in cases of

myocarditis Myocarditis, also known as inflammatory cardiomyopathy, is an acquired cardiomyopathy due to inflammation of the heart muscle. Symptoms can include shortness of breath, chest pain, decreased ability to exercise, and an irregular heartbeat. The ...

and

encephalitis Encephalitis is inflammation of the brain. The severity can be variable with symptoms including reduction or alteration in consciousness, headache, fever, confusion, a stiff neck, and vomiting. Complications may include seizures, hallucinations, ...

Taxonomy

Eighteen types of human parechovirus have been identified: human parechovirus 1 (HPeV1, formerly

echovirus Echovirus is a polyphyletic group of viruses associated with enteric disease in humans. The name is derived from "enteric cytopathic human orphan virus". These viruses were originally not associated with disease, but many have since been identifie ...

22), human parechovirus 2 (formerly

23), and HPeV3 to HPeV18. A total of 15 genotypes are currently recognised.Chieochansin T, Vichiwattana P, Korkong S, Theamboonlers A, Poovorawan Y (2011) Molecular epidemiology, genome characterization, and recombination event of human parechovirus. Virology

Species

The ICTV recognises the following six species: * ''Parechovirus A'' (formerly ''Human parechovirus''; human host) * ''

Parechovirus B ''Parechovirus B'', formerly called the ''Ljungan virus'', was first discovered in the mid-1990s after being isolated from a bank vole near the Ljungan river in Medelpad county, Sweden. It has since been established that ''Parechovirus B'', which ...

'' (formerly ''Ljungan virus''; rodent host) * ''Parechovirus C'' (formerly ''Sebokele virus 1''; rodent host) * ''Parechovirus D'' (formerly ''Ferret parechovirus'';

carnivora Carnivora is a Clade, monophyletic order of Placentalia, placental mammals consisting of the most recent common ancestor of all felidae, cat-like and canidae, dog-like animals, and all descendants of that ancestor. Members of this group are f ...

n host) * ''Parechovirus E'' * ''Parechovirus F'' An additional two species are recognised by Picornaviridae.com but not by the ICTV: * Ljungan/Sebokele-like parechovirus (LCLPV) (falcon host, Hungary) * Manhattan parechovirus (MPeV) (rodent host, United States)Picornaviridae.com: Manhatten PeV gene sequences
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Structure

Parechoviruses are non-enveloped, with icosahedral, spherical, and round geometries, and T=pseudo3 symmetry. The diameter is around 30 nm. Genomes are linear and non-segmented, around 7.3kb in length.

Life cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by attachment of the virus to host receptors, which mediates endocytosis. Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription is the method of transcription. The virus exits the host cell by lysis, and viroporins.

Clinical information

Human parechoviruses cause mild, gastrointestinal or respiratory illness, but have been implicated in cases of

and

. Human parechoviruses are commonly spread and more than 95% of human cases are infected early in life, within two to five years of age. Parechovirus B has been proposed as a zoonotic virus, associated with

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...

and intrauterine fetal death in humans. However, the data regarding these features are currently limited and need to be confirmed. Parechovirus is a Biosafety Level 2 organism.

History

The first parechoviruses (E22 and E23) were isolated in 1956, and recognized as a new genus in 1996. Parechovirus B was first isolated from

bank vole The bank vole (''Myodes glareolus'') is a small vole with red-brown fur and some grey patches, with a tail about half as long as its body. A rodent, it lives in woodland areas and is around in length. The bank vole is found in much of Europe an ...

s (''Myodes glareolus'', formerly ''Clethrionomys glareolus'') in the mid-1990s. Human parechovirus type 3 (HPeV3) was found in at least 20 U.S. young infants in 2014. Those numbers include a set of identical triplets from central

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...

, who contracted the virus and were diagnosed nearly two months later after a flurry of tests, as this was the first known case in those health systems. The 2014 outbreak is a higher number than expected, and is thought to be linked to maternal-fetal transmission.

References

External links

3D macromolecular structures of Parechoviruses from the EM Data Bank(EMDB)
{{Taxonbar, from=Q4346377 Picornaviridae Virus genera