Coltivirus

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Coltivirus
Coltivirus virion.jpg
Coltivirus virion. [1]
Virus classification Red Pencil Icon.png
(unranked): Virus
Realm: Riboviria
Kingdom: Orthornavirae
Phylum: Duplornaviricota
Class: Resentoviricetes
Order: Reovirales
Family: Reoviridae
Subfamily: Spinareovirinae
Genus:Coltivirus

Coltivirus is a genus of viruses (belonging to the Reoviridae family) that infects vertebrates and invertebrates. It includes the causative agent of Colorado tick fever. [2] Colorado tick fever virus can cause a fever, chills, headache, photophobia, myalgia, arthralgia, and lethargy. Children, in particular, may develop a hemorrhagic disease. Leukopenia with both lymphocytes and neutrophils is very common for Colorado tick fever virus. In either case, the infection can lead to encephalitis or meningitis. [3]

Contents

Virology

Coltivirus is a genus of viruses. Viruses are intracellular parasites that do not have the necessary means to reproduce on their own, so they have instead to hijack the machinery of a host cell. Only then can they synthesize their viral proteins and create progeny. There are two types of viruses, distinguished by their type of genetic material.

DNA viruses have genomes consisting of deoxyribonucleic acid (or DNA), while RNA viruses, like Coltivirus, have an RNA (ribonucleic acid) genome, which is segmented (multipartite). [4] [1]

General description

Ixodes ricinus range map, the European Eyach virus vector Ixodes ricinus range map.svg
Ixodes ricinus range map, the European Eyach virus vector

The name "Coltivirus" is derived from the type species of the genus, the Colorado tick fever virus ("Colorado tick"). Coltivirus is in the family Reoviridae, which contains eight genera. Orthoreovirus, Orbivirus, Coltivirus, Rotavirus, Aquareovirus, Cypovirus, Phytoreovirus, and Fijivirus. [5] Coltivirus and Orbivirus together contain about 109 serotypes, and only four of these cause human disease. [5] Ticks are the main vectors of coltiviruses. [6] Colorado tick fever was originally recorded in the 19th century, and today it is one of the most common tick-borne diseases in the United States. [3]

The European Eyach virus and the Colorado tick fever virus are known relatives due to cognate genes, 55% to 88% of amino acid similarity, and similarities at the microscopic level that cannot be distinguished. [6] To find these similarities, a genome sequence analysis was completed. [7] One theory of how the European Eyach virus is proposed to have come about in Europe is by the migration of lagomorphs from North America over fifty million years ago. [6] Since then, the virus took on some differences, and is now considered its own species of virus. European Eyach virus was isolated in 1976 from Ixodes ricinus ticks in Europe and in 1981 from the same species along with Ixodes ventalloi in 1981.

Taxonomy

The following five species are assigned to the genus: [8]

Other characteristics

Morphology and physiology

Tai Forest coltivirus (white arrows) with inner and outer icosahedral capsids of around 70 nm in diameter 12985 2017 843 Fig1 HTML.png
Taï Forest coltivirus (white arrows) with inner and outer icosahedral capsids of around 70 nm in diameter

The Coltivirus virions are about 60-80 nanometers in diameter and are not enveloped, and are generally a spherical shape with icosahedral symmetry. Each virion has two concentric capsid shells surrounding a core of about 50 nanometers in diameter. The surface of the particle is relatively smooth. [7] The virus loses its infectivity when the surrounding fluid becomes acidic, around a pH of three, but is stable when the pH is between seven and eight. It also stops being a threat when the temperature becomes about fifty-five degrees Celsius. [7]

GenusStructureSymmetryCapsidGenomic arrangementGenomic segmentation
ColtivirusIcosahedralT=13, T=2Non-envelopedLinearSegmented

Genome and genomic organization

Genome map of species Colorado tick fever virus (CTFV) showing several segments. Coltivirus genome.jpg
Genome map of species Colorado tick fever virus (CTFV) showing several segments.

Coltiviruses have twelve segments of linear, double-stranded RNA. When the genome is processed with gel electrophoresis, the segments migrate as three class sizes (three bands). Each segment is replicated, and the largest segment encodes RNA polymerase. [7] Locations of other proteins along the genome have yet to be determined.

Pathogenesis and viral reproduction

Red blood cells are the target of Colorado tick fever virus Blausen 0761 RedBloodCells.png
Red blood cells are the target of Colorado tick fever virus

Coltiviruses replicate in the cytoplasm in cells of both arthropods and vertebrates, but they are only transmitted by the arthropods. [5] When the virus replicates, the virion outer shell has to be removed in order for RNA polymerase to be activated to continue the replication of the virion's RNA. Reassortment of the RNA segments in progeny is common, and this plays a role in some of the genetic diversity between the serotypes. Sometimes, this can lead to fast changes in the properties of the viruses. [5]

The main species of Coltivirus, Colorado tick fever virus (CTF), infects the Rocky Mountain wood tick (Dermacentor andersoni). This species of tick can be found in areas with shrubs, lightly wooded locations, grasslands, and on hiking or biking trails. All life stages of this tick can infect vertebrates with Colorado tick fever virus (larva, nymph, and adult). Unfortunately, mature D. andersoni prefer to feed on medium or large mammals that are walking around the knee-high plants. [9] Oftentimes, this infection takes place when the tick larvae feed on rodents, like squirrels, that are already infected with virus. The tick's saliva then contains the virus, and it becomes infectious for life. The adult tick then transmits the virus to humans through a bite, where it infects bone marrow cells. [5]

The virus replicates in those bone marrow cells, which disrupts the development and replication of leukocytes (white blood cells), eosinophils, and basophils. Because of this, thrombocytopenia could also a potential result. Erythrocytes, which are enucleated red blood cells, seem to be infected while they are erythroblasts, their nucleated precursor stage. [5] The virus stays in these red blood cells without harming it for up to four months. [7] Here, it is protected from the immune system's attacks. [3] Antibody to the virus is found only about two weeks after symptoms begin to show, but the virus can still be found in blood cells for about six weeks. [5]

GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
ColtivirusHumans; rodents; ticks; mosquitoeErythrocytesCell receptor endocytosisCell deathCytoplasmCytoplasmArthropod bite

Symptoms and diagnosis of Colorado tick fever virus (CTFV)

Colorado tick fever virus can cause a fever, chills, headache, photophobia, myalgia, arthralgia, and lethargy. Children, in particular, may develop a hemorrhagic disease. Leukopenia with both lymphocytes and neutrophils is very common for Colorado tick fever virus. In either case, the infection can lead to encephalitis or meningitis. [3]

For diagnosis, the erythrocytes can be isolated by injecting them into a tissue culture and checking to see if they are infected. Also, the antigen for Colorado tick fever virus can be identified using the immunofluorescence microscopy. In this method, the antigens on the surface of the erythrocytes are marked with fluorescence and examined under a fluorescence microscope. [5]

Epidemiology and control

Range map of Dermacentor andersoni in the United States Dermacentor andersoni range map.svg
Range map of Dermacentor andersoni in the United States
Brown shading represents the Rocky Mountain Range RockyMountainsLocatorMap.png
Brown shading represents the Rocky Mountain Range

The distribution of Colorado tick fever virus is in the Rocky Mountain area of the United States at elevations between four and ten thousand feet. [7] Not surprisingly, Colorado tick fever virus can be found in places like California, Colorado, Idaho, Montana, Nevada, Oregon, Utah, Washington, Wyoming, British Columbia, and Alberta. This is roughly the same distribution as the tick that transmits the virus, shown in the adjacent picture. [5]

The virus circulates between ticks and rodents, with humans being the secondary hosts. [5] People at risk for catching the disease are hikers and campers that are in the risk areas. Also, April, May, and June are when the infections mainly occur, because this is the time when the adult ticks are prevalent in the environment. Unfortunately, this is also when the weather is pleasant for hiking and camping. The best way to avoid getting bitten and catching this disease is wearing long sleeves or pants, avoiding high tick-infested areas, and wearing tick repellent. [5]

Treatment

Reverse transcription-polymerase chain reaction (RT-PCR) procedure Reverse transcription polymerase chain reaction.jpg
Reverse transcription-polymerase chain reaction (RT-PCR) procedure

Colorado tick fever virus can be detected in a patient with a reverse transcription polymerase chain reaction (RT-PCR), where even a single virion and its genetic material can be detected. [7] The antigens to the virus can also be detected using immunofluorescence. [5] There is currently no known vaccine or treatment available to treat these Coltiviruses, but 3'-fluoro-3'-deoxyadenosine, a nucleoside analog, halts replication of Colorado tick fever virus in vitro. [5]

Related Research Articles

<span class="mw-page-title-main">Colorado tick fever</span> Medical condition

Colorado tick fever (CTF) is a viral infection (Coltivirus) transmitted from the bite of an infected Rocky Mountain wood tick. It should not be confused with the bacterial tick-borne infection, Rocky Mountain spotted fever. Colorado tick fever is probably the same disease that American pioneers referred to as "mountain fever".

<i>Reoviridae</i> Family of viruses

Reoviridae is a family of double-stranded RNA viruses. Member viruses have a wide host range, including vertebrates, invertebrates, plants, protists and fungi. They lack lipid envelopes and package their segmented genome within multi-layered capsids. Lack of a lipid envelope has allowed three-dimensional structures of these large complex viruses to be obtained, revealing a structural and likely evolutionary relationship to the cystovirus family of bacteriophage. There are currently 97 species in this family, divided among 15 genera in two subfamilies. Reoviruses can affect the gastrointestinal system and respiratory tract. The name "reo-" is an acronym for "respiratory enteric orphan" viruses. The term "orphan virus" refers to the fact that some of these viruses have been observed not associated with any known disease. Even though viruses in the family Reoviridae have more recently been identified with various diseases, the original name is still used.

<i>Bunyavirales</i> Order of RNA viruses

Bunyavirales is an order of segmented negative-strand RNA viruses with mainly tripartite genomes. Member viruses infect arthropods, plants, protozoans, and vertebrates. It is the only order in the class Ellioviricetes. The name Bunyavirales derives from Bunyamwera, where the original type species Bunyamwera orthobunyavirus was first discovered. Ellioviricetes is named in honor of late virologist Richard M. Elliott for his early work on bunyaviruses.

<i>Thogotovirus</i> Genus of viruses

Thogotovirus is a genus of enveloped RNA viruses, one of seven genera in the virus family Orthomyxoviridae. Their single-stranded, negative-sense RNA genome has six or seven segments. Thogotoviruses are distinguished from most other orthomyxoviruses by being arboviruses – viruses that are transmitted by arthropods, in this case usually ticks. Thogotoviruses can replicate in both tick cells and vertebrate cells; one subtype has also been isolated from mosquitoes. A consequence of being transmitted by blood-sucking vectors is that the virus must spread systemically in the vertebrate host – unlike influenza viruses, which are transmitted by respiratory droplets and are usually confined to the respiratory system.

<i>Orbivirus</i> Genus of viruses

Orbivirus is a genus of double-stranded RNA viruses in the family Reoviridae and subfamily Sedoreovirinae. Unlike other reoviruses, orbiviruses are arboviruses. They can infect and replicate within a wide range of arthropod and vertebrate hosts. Orbiviruses are named after their characteristic doughnut-shaped capsomers.

<span class="mw-page-title-main">Golden shiner virus</span> Species of virus

The golden shiner virus is an aquatic virus that infects a bait fish known as the golden shiner and to a lesser extent, aquatic animals like crustaceans and molluscs. About 6 virus species have been identified in this genus since the late 1970s. It causes death through a hemorrhagic shock. Symptoms include bleeding from the back eyes and the head. The virus is 70 nm in diameter and replicates best at 20-30 degrees Celsius. The virus has properties similar to those of the pancreatic necrosis virus. This could mean that golden shiners are more susceptible in the summer.

<span class="mw-page-title-main">Veterinary virology</span> Study of viruses affecting animals

Veterinary virology is the study of viruses in non-human animals. It is an important branch of veterinary medicine.

<span class="mw-page-title-main">Double-stranded RNA viruses</span> Type of virus according to Baltimore classification

Double-stranded RNA viruses are a polyphyletic group of viruses that have double-stranded genomes made of ribonucleic acid. The double-stranded genome is used to transcribe a positive-strand RNA by the viral RNA-dependent RNA polymerase (RdRp). The positive-strand RNA may be used as messenger RNA (mRNA) which can be translated into viral proteins by the host cell's ribosomes. The positive-strand RNA can also be replicated by the RdRp to create a new double-stranded viral genome.

<i>Banna virus</i> Species of virus

Banna virus (BAV) is a virus belonging to Reoviridae, a family of segmented, non-enveloped, double-stranded RNA viruses. It is an arbovirus, being primarily transmitted to humans from the bite of infected mosquitoes of the genus Culex. Pigs and cattle have also been shown to become infected. The most common symptom of infection is fever, but in some cases encephalitis may occur. There is no specific treatment for infection, so treatment is aimed at alleviating the severity of symptoms until the immune system has cleared the infection.

<i>Seadornavirus</i> Genus of viruses

Seadornavirus is a genus of viruses, in the family Reoviridae, in the subfamily Sedoreovirinae. Human, cattle, pig, and mosquitoes serve as natural hosts. There are three species in this genus: Banna virus (BAV), Kadipiro virus and Liao ning virus. Each of these viruses has been isolated from Aedes, Anopheles and Culex mosquito populations, but only BAV has been shown to cause infection in humans, in which the symptoms are similar to Japanese encephalitis—fever, malaise and encephalitis. The word seadornavirus is an portmanteau, meaning Southeast Asian dodeca RNA virus.

Liao ning virus (LNV) is a virus belonging to the genus Seadornavirus within the family Reoviridae, a family of segmented, non-enveloped, double-stranded RNA viruses. LNV was first discovered in Aedes dorsalis populations in the Liaoning province of the People's Republic of China in 2006 from mosquito samples obtained in 1997. Its geographic distribution was previously thought to be limited to China, but it has since been found in mosquito populations in Australia. In addition to Aedes dorsalis, LNV has been isolated from Culex species.

<i>Sedoreovirinae</i> Subfamily of viruses

Sedoreovirinae is a subfamily of the Reoviridae family of viruses. Viruses in this subfamily are distinguished by the absence of a turreted protein on the inner capsid to produce a smooth surface.

Batai orthobunyavirus (BATV) is a RNA virus belonging to order Bunyavirales, genus Orthobunyavirus.

Epizootic hemorrhagic disease virus, often abbreviated to EHDV, is a species of the genus Orbivirus, a member of the family Reoviridae. It is the causative agent of epizootic hemorrhagic disease, an acute, infectious, and often fatal disease of wild ruminants. In North America, the most severely affected ruminant is the white-tailed deer, although it may also infect mule deer, black-tailed deer, elk, bighorn sheep, and pronghorn antelope. It is often mistakenly referred to as “bluetongue virus” (BTV), another Orbivirus that like EHDV causes the host to develop a characteristic blue tongue due to systemic hemorrhaging and lack of oxygen in the blood. Despite showing clinical similarities, these two viruses are genetically distinct.

Mimoreovirus is a genus of viruses, in the family Reoviridae, in the subfamily Sedoreovirinae. The only isolate infects the marine photosynthetic protist Micromonas pusilla, a prasinophyte. There is only one species in this genus: Micromonas pusilla reovirus.

<i>Nodamura virus</i> Species of virus

Nodamura virus (NoV) is a member of the family Nodaviridae, which was originally isolated from mosquitoes in Japan near the village of Nodamura in 1956. Other members of Nodaviridae are flock house virus (FHV) and black beetle virus (BBV). NoV has been found to multiply in several insect and tick species; however, these infected individuals seem to be asymptomatic. Nodamura virus is the only member of the genus Alphanodavirus that can infect insects, fish, and mammals.

Eyach virus (EYAV) is a viral infection in the Reoviridae family transmitted by a tick vector. It has been isolated from Ixodes ricinus and I. ventalloi ticks in Europe.

Mammalian orthoreovirus (MRV) is a double-stranded RNA virus. It is a part of the family Reoviridae, as well as the subfamily Spinareovirinae. As seen in the name, the Mammalian Ortheoreovirus infects numerous mammalian species and vertebrates which serve as natural hosts. Some diseases that occur as a result of this virus or are associated with this virus include mild upper respiratory illness, and gastrointestinal illness. Examples of these are: upper respiratory tract syndromes, gastroenteritis, biliary atresia, obstructive hydrocephalus, jaundice, alopecia, conjunctivitis, and ‘oily hair’ associated with steatorrhea.

<i>Sepik virus</i> Mosquito transmitted virus endemic to Papua New Guinea

Sepik virus (SEPV) is an arthropod-borne virus (arbovirus) of the genus Flavivirus and family Flaviviridae. Flaviviridae is one of the most well characterized viral families, as it contains many well-known viruses that cause diseases that have become very prevalent in the world, like Dengue virus. The genus Flavivirus is one of the largest viral genera and encompasses over 50 viral species, including tick and mosquito borne viruses like Yellow fever virus and West Nile virus. Sepik virus is much less well known and has not been as well-classified as other viruses because it has not been known of for very long. Sepik virus was first isolated in 1966 from the mosquito Mansoniaseptempunctata, and it derives its name from the Sepik River area in Papua New Guinea, where it was first found. The geographic range of Sepik virus is limited to Papua New Guinea, due to its isolation.

<i>Orthornavirae</i> Kingdom of viruses

Orthornavirae is a kingdom of viruses that have genomes made of ribonucleic acid (RNA), those genomes encoding an RNA-dependent RNA polymerase (RdRp). The RdRp is used to transcribe the viral RNA genome into messenger RNA (mRNA) and to replicate the genome. Viruses in this kingdom also share a number of characteristics involving evolution, including high rates of genetic mutations, recombinations, and reassortments.

References

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