Cardiovirus are a group of

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 ...

within order ''

Picornavirales ''Picornavirales'' is an order of viruses with vertebrate, invertebrate, protist and plant hosts. The name has a dual etymology. First, ''picorna-'' is an acronym for poliovirus, insensitivity to ether, coxsackievirus, orphan virus, rhinovirus, ...

'', 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 ...

''.

Vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

serve as natural hosts for these viruses.

Taxonomy

There are currently six species in the genus: * ''

Cardiovirus A Cardiovirus A is a member of the ''Picornaviridae'' family. Infection with the virus causes encephalomyocarditis and reproductive disease in pigs. Although a variety of mammals may host the virus, pigs are classed as the domestic host as they ar ...

'' * '' Cardiovirus B'' * ''

Cardiovirus C Cardiovirus are a group of viruses within order ''Picornavirales'', family ''Picornaviridae''. Vertebrates serve as natural hosts for these viruses. Taxonomy There are currently six species in the genus: * ''Cardiovirus A'' * '' Cardiovirus B'' ...

'' * ''

Cardiovirus D Cardiovirus are a group of viruses within order ''Picornavirales'', family ''Picornaviridae''. Vertebrates serve as natural hosts for these viruses. Taxonomy There are currently six species in the genus: * ''Cardiovirus A'' * '' Cardiovirus B'' ...

'' * ''

Cardiovirus E Cardiovirus are a group of viruses within order ''Picornavirales'', family ''Picornaviridae''. Vertebrates serve as natural hosts for these viruses. Taxonomy There are currently six species in the genus: * ''Cardiovirus A'' * '' Cardiovirus B'' ...

'' * '' Cardiovirus F'' ''Cardiovirus A'' is composed of only one serotype,

encephalomyocarditis virus Cardiovirus A is a member of the ''Picornaviridae'' family. Infection with the virus causes encephalomyocarditis and reproductive disease in pigs. Although a variety of mammals may host the virus, pigs are classed as the domestic host as they are ...

(EMCV). ''Cardiovirus B'' consists of four viruses that are most probably serologically distinct. These are Theiler's Murine encephalomyelitis virus (TMEV), Vilyuisk human encephalomyelitis virus (VHEV), a Theiler-like rat virus (TRV) (which has yet to be named) and Saffold virus (SAF-V). Of these 4, only VHEV and SAF-V are thought to cause infection in humans. Thus far, ''Cardiovirus C'' has only been observed in the

brown rat The brown rat (''Rattus norvegicus''), also known as the common rat, street rat, sewer rat, wharf rat, Hanover rat, Norway rat, Norwegian rat and Parisian rat, is a widespread species of common rat. One of the largest muroids, it is a brown o ...

Structure

Cardioviruses are single-stranded RNA, non-enveloped viruses with icosahedral or spherical geometries, and a T=pseudo3 icosahedral capsid protein geometry. The diameter is around 30 nm. Genomes are linear and non-segmented, around 7.8 kb in length. The T=pseudo3 icosahedral capsid of Cadiovirus is made of 60

protomer In structural biology, a protomer is the structural unit of an oligomeric protein. It is the smallest unit composed of at least two different protein chains that form a larger hetero-oligomer by association of two or more copies of this unit. The ...

s, each of which contains 4 polypeptides: VP1, VP2, VP3, and VP4. Inside the capsid of the virus there is a single linear, positive single-stranded RNA. On both the 3' and 5' ends of the genome there are untranslated regions . These untranslated regions of genome are important for the DNA replication, with the untranslated region on the 5' side being the location of internal ribosomal entry site (IRES).

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. Translation takes place by −1 ribosomal frameshifting, viral initiation, and ribosomal skipping. The virus exits the host cell by lysis, and viroporins. Human and vertebrates serve as the natural host. Transmission routes are

zoonosis A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a bacterium, virus, parasite or prion) that has jumped from a non-human (usually a vertebrate) to a human. ...

and fomite. The 3’ end of the genome encodes a

polyA Polyadenylation is the addition of a poly(A) tail to an RNA transcript, typically a messenger RNA (mRNA). The poly(A) tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In euka ...

tail while the 5’ end encodes a genome-linked protein. A unique feature of this genus is the presence of the L* protein, 18kDa, that is made out of frame from the polyprotein and is present in the DA subgroup of TMEV. It has been found to be important for the virus pathogenesis. In the case of ''Cardiovirus A'', the virus can cause encephalitis and myocarditis, mostly in rodents, which are natural

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

s. The virus is transmitted from rodents to other animals. Severe epidemics have been seen in swine and

elephant Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae an ...

s. Replication of cardioviruses is dependent on a structured RNA element called the

Cardiovirus cis-acting replication element (CRE) This family represents a Cardiovirus cis-acting replication element (CRE) which is located within the region encoding the capsid protein VP2 and is required for viral replication Viral replication is the formation of biological viruses during ...

Clinical

Human cardioviruses were first isolated in 1981. Seven additional isolates have since been described in North America, Europe and South Asia. They have been associated with gastroenteritis, influenza-like symptoms and non-

polio Poliomyelitis, commonly shortened to polio, is an infectious disease caused by the poliovirus. Approximately 70% of cases are asymptomatic; mild symptoms which can occur include sore throat and fever; in a proportion of cases more severe s ...

-associated

acute flaccid paralysis Flaccid paralysis is a neurological condition characterized by weakness or paralysis and reduced muscle tone without other obvious cause (e.g., trauma). This abnormal condition may be caused by disease or by trauma affecting the nerves associate ...

. The first infection of cardiovirus in humans was identified in 2007 in a stool sample of an infant that was experiencing fever of unknown origin. It was subsequently named the Saffold virus after the lead researcher,

Morris Saffold Jones Morris may refer to: Places Australia *St Morris, South Australia, place in South Australia Canada * Morris Township, Ontario, now part of the municipality of Morris-Turnberry * Rural Municipality of Morris, Manitoba ** Morris, Manitob ...

. Other pathogenic cardioviruses isolated from humans include the

Syr-Darya valley fever virus The Syr Darya (, ),, , ; rus, Сырдарья́, Syrdarjja, p=sɨrdɐˈrʲja; fa, سيردريا, Sirdaryâ; tg, Сирдарё, Sirdaryo; tr, Seyhun, Siri Derya; ar, سيحون, Seyḥūn; uz, Sirdaryo, script-Latn/. historically known ...

and Vilyuisk human encephalomyelitis virus.Anonymous. (2014) Genetic characterization of the Syr-Darya valley fever virus (SDVFV) (Picornaviridae, Cardiovirus) isolated from the blood of the patients and ticks ''Hyalomma as. asiaticum'' (Hyalomminae), ''Dermacentor daghestanicus'' (Rhipicephalinae) (Ixodidae) and ''Ornithodoros coniceps'' (Argasidae) in Kazakhstan and Turkmenistan. Vopr Virusol 59(4):15–19Diseases associated with cardioviruses include:

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 ...

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, ...

multiple sclerosis Multiple (cerebral) sclerosis (MS), also known as encephalomyelitis disseminata or disseminated sclerosis, is the most common demyelinating disease, in which the insulating covers of nerve cells in the brain and spinal cord are damaged. This d ...

, and

type 1 diabetes Type 1 diabetes (T1D), formerly known as juvenile diabetes, is an autoimmune disease that originates when cells that make insulin (beta cells) are destroyed by the immune system. Insulin is a hormone required for the cells to use blood sugar for ...

References

External links