Transmissible gastroenteritis coronavirus

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Transmissible Gastroenteritis Coronavirus
Canine coronavirus.jpg
Canine coronavirus (the same species as TGEV) antigen in canine lung tissue
Virus classification
Group:Group IV ((+)ssRNA)
Order: Nidovirales
Family: Coronaviridae
Subfamily: Coronavirinae
Genus: Alphacoronavirus
Species: Alphacoronavirus 1
Subspecies:Transmissible Gastroenteritis Coronavirus

Transmissible gastroenteritis coronavirus (TGEV) is a virus belonging to the family Coronaviridae , genus Alphacoronavirus , species Alphacoronavirus 1 . [1] TGEV are enveloped viruses with a positive-sense single-stranded RNA genome and a helical symmetry. The genomic size of coronaviruses ranges from approximately 28.6 kilobases. [2]

Virus Type of non-cellular infectious agent

A virus is a small infectious agent that replicates only inside the living cells of an organism. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea.

<i>Coronaviridae</i> family of virus

Coronaviridae is a family of enveloped, positive-sense, single-stranded RNA viruses. The viral genome is 26–32 kb in length. The particles are typically decorated with large (~20 nm), club- or petal-shaped surface projections, which in electron micrographs of spherical particles create an image reminiscent of the solar corona. Members of this family are thus referred to as coronaviruses.

Alphacoronaviruses are the first of the four genera, Alpha-, Beta-, Gamma-, and Deltacoronavirus in the subfamily Coronavirinae of the family Coronaviridae. Coronaviruses are enveloped, positive-sense, single-stranded RNA viruses that include both human and zoonotic species. Within this subfamily, viruses have spherical virions with club-shaped surface projections and a core shell. The name is from the Latin corona, meaning crown, which describes the appearance of the projections seen under electron microscopy that resemble a solar corona. This genus contains what were previously considered phylogroup 1 coronaviruses.

Contents

Proteins that contribute to the overall structure of TGEV includes the spike (S), envelope (E), membrane (M) and nucleocapsid (N). Other coronaviruses belonging to Alphacoronavirus 1 species include Feline coronavirus , Canine coronavirus and Feline infectious peritonitis virus .

Feline coronavirus (FCoV) is a positive-stranded RNA virus that is infectious to cats worldwide. This virus is part of the species Alphacoronavirus 1 of the genus Alphacoronavirus belonging to the virus family Coronaviridae. Alphacoronavirus 1 also includes the canine coronavirus (CCoV) and the porcine transmissible gastroenteritis coronavirus (TGEV). It has two different forms; the FECV that infects the intestines and the FIPV that causes the disease feline infectious peritonitis (FIP).

Canine coronavirus species of virus

Canine coronavirus is a virus of the family Coronaviridae that causes a highly contagious intestinal disease worldwide in dogs. It was discovered in 1971 in Germany during an outbreak in sentry dogs.

Biology

TGEV belongs to the family Coronaviridae, genus Alphacoronavirus, species Alphacoronavirus 1. It is an enveloped virus with a positive single stranded RNA genome. TGEV has three major structural proteins, which are phosphoprotein (N), integral membrane protein (E1), and large glycoprotein (E2). The N protein encapsulates the genomic RNA, and the S protein forms viral projections.

The 3' segment of about 8000 nucleotides encodes subgenomic RNAs. The remaining part of the genome encodes viral replicase. The three largest gene sequence from 5' to 3' is in the order of E2 to E1 to N. There are about seven other open reading frames that are not structurally related. There are very little overlaps among the genes, and is densely packed. A negative strand is synthesized to serve as a template for transcribing RNAs of one genome size and several subgenome sized RNAs.

The E2 protein forms a petal-shaped 20 nm long projection from the virus's surface. The E2 protein is thought to be involved in pathogenesis by helping the virus enter the host cytoplasm. The E2 protein initially has 1447residues, and then a short hydrophobic sequence is cleaved. After glycosylation of the protein in the golgi, the protein is then incorporated into the new virus. There are several functional domains within the E2 protein. A 20 residue hydrophobic segment at the C-terminus anchors the protein in the lipid membrane. The rest of the protein is divided into two parts, a hydrophilic stretch that is inside the virus and a cysteine rich stretch that are possibly fatty acylation sites. The E1 protein is mostly embedded in the lipid envelop and hence plays an essential role in virus architecture. The E1 protein is postulated to interact with the lymphocyte membrane, which leads to the induction of IFN-coding genes.

Morphology

The morphology of TGEV was mostly determined by electron microscopy techniques. The morphology is similar to myxovirus and oncogenic virus in that they have surface projections and an envelop. The viruses are mainly circular in shape with a diameter ranging from 100 to 150 nm including the surface projections. The projections were mainly petal-shaped attached by a very narrow stalk. The projections seemed to be very easily detached from the virus and were only found on select areas.

Pathology

TGEV infects pigs. However, in young pigs, the mortality rate is close to 100%. The pathology of TGEV is similar to that of other coronaviruses. Coronaviruses enter the host by first attaching to the host cell using the spike glycoprotein. The S protein interacts with the porcine aminopeptidase N (pAPN), a cellular receptor, to aide in its entry. The same cell receptor is also a point of contact for Human Coronaviruses. A domain in the S spike protein is recognized by pAPN, and transfection of pAPN occurs to nonpermissive cells and infects them with TGEV. Once the virus infects the host, it multiplies in the cell lining of the small intestine resulting in the loss of absorptive cells that in turn leads to shortening of villi. The infected swine then has reduced capability for digesting food and die from dehydration.

Engineering TGEV coronavirus

The Transmissible Gastroenteritis Virus has been engineered as an expression vector. The vector was constructed by replacing the nonessential 3a and 3b ORF, which is driven by the transcription-regulating sequences (TRS) with green fluorescent protein. The resulting construct was still enteropathogenic, but with reduced growth. The infection of cells with this altered virus elicits a specific lactogenic immune response against the heterologous protein. The application of this vector is in the development of a vaccine or even gene therapy. The motivation for engineering the TGEV genome is that coronaviruses have large genomes, so they have room for insertion of foreign genes. Coronaviruses also infect the respiratory tract, and they can be used to target antigens to that area and generate some immune response.

Respiratory tract Organs involved in transmission of air to and from the point where gases diffuse into tissue

In humans, the respiratory tract is the part of the anatomy of the respiratory system involved with the process of respiration. Air is breathed in through the nose or the mouth. In the nasal cavity, a layer of mucous membrane acts as a filter and traps pollutants and other harmful substances found in the air. Next, air moves into the pharynx, a passage that contains the intersection between the esophagus and the larynx. The opening of the larynx has a special flap of cartilage, the epiglottis, that opens to allow air to pass through but closes to prevent food from moving into the airway.

Related Research Articles

Retrovirus family of viruses

A retrovirus is a type of RNA virus that inserts a copy of its genome into the DNA of a host cell that it invades, thus changing the genome of that cell. Such viruses are specifically classified as single-stranded positive-sense RNA viruses.

Coronavirus genus of viruses

Coronaviruses are species of virus belonging to the subfamily Coronavirinae in the family Coronaviridae, in the order Nidovirales. Coronaviruses are enveloped viruses with a positive-sense single-stranded RNA genome and with a nucleocapsid of helical symmetry. The genomic size of coronaviruses ranges from approximately 26 to 32 kilobases, the largest for an RNA virus.

<i>Severe acute respiratory syndrome-related coronavirus</i> species of virus

The Severe acute respiratory syndrome-related coronavirus, sometimes shortened to SARS-CoV, is the virus that causes severe acute respiratory syndrome (SARS). On April 16, 2003, following the outbreak of SARS in Asia and secondary cases elsewhere in the world, the World Health Organization (WHO) issued a press release stating that the coronavirus identified by a number of laboratories was the official cause of SARS. Samples of the virus are being held in laboratories in New York City, San Francisco, Manila, Hong Kong, and Toronto.

Okavirus is a genus of viruses in the order Nidovirales, in the family Roniviridae. Okaviruses infect crustaceans, mostly prawns. There is currently only one species in this genus: the type species Gill-associated virus. Diseases associated with this genus include: GAV: reddening, biofouling with exoparasites, emaciation, massive mortality; YHV: yellow head, arrest of feeding. massive mortality. The name is derived from the 'Oka' or lymphoid organ in which the viruses are commonly detected and in which pathology occurs during acute infections. Lymphoid organs are anatomical structures common to penaeid shrimp.

Nidovirales is an order of viruses with animal and human hosts. It includes the families Coronaviridae, Arteriviridae,Roniviridae and Mesoniviridae.

<i>Alphavirus</i> genus of viruses

In biology and immunology, an Alphavirus belongs to group IV of the Baltimore classification of the Togaviridae family of viruses, according to the system of classification based on viral genome composition introduced by David Baltimore in 1971. Alphaviruses, like all other group IV viruses, have a positive sense, single-stranded RNA genome. There are thirty alphaviruses able to infect various vertebrates such as humans, rodents, fish, birds, and larger mammals such as horses as well as invertebrates. Transmission between species and individuals occurs mainly via mosquitoes, making the alphaviruses a member of the collection of arboviruses – or arthropod-borne viruses. Alphavirus particles are enveloped, have a 70 nm diameter, tend to be spherical, and have a 40 nm isometric nucleocapsid.

Torovirus genus of viruses

Torovirus is a genus of viruses in the order Nidovirales, in the family Tobaniviridae, in the subfamily Torovirinae. They primarily infect vertebrates., especially cattle, pig, and horse. There are currently three species in this genus including the type species Equine torovirus. Diseases associated with this genus include: gastroenteritis, which commonly presents in mammals, but rarely in humans. Torovirus is the sole genus in the monotypic subfamily Torovirinae. Torovirus is also a monotypic taxon, containing only one subgenus, Renitovirus.

<i>Betacoronavirus</i> genus of viruses

Betacoronaviruses are one of four genera of coronaviruses of the subfamily Orthocoronavirinae in the family Coronaviridae, of the order Nidovirales. They are enveloped, positive-sense, single-stranded RNA viruses of zoonotic origin. The coronavirus genera are each composed of varying viral lineages with the betacoronavirus genus containing four such lineages.

Human coronavirus OC43 is a subspecies of enveloped, positive-stranded RNA virus in the species Betacoronavirus 1.

Orthocoronavirinae is one of two subfamilies in the family Coronaviridae. It is subdivided into the genera Alphacoronavirus, Betacoronavirus, Gammacoronavirus, and Deltacoronavirus. These include phylogenetically compact genogroups of enveloped, positive-sense, single-stranded RNA and with a nucleocapsid of helical symmetry. The genomic size of coronaviruses ranges from approximately 26 to 32 kilobases, extraordinarily large for an RNA virus. Their numbers are growing rapidly with several novel coronaviruses being recently discovered including Middle East respiratory syndrome coronavirus MERS-CoV discovered in 2012.

Deltacoronavirus is one of the four genera, Alpha-, Beta-, Gamma-, and Delta- in the subfamily Orthocoronavirinae of the family Coronaviridae. They are enveloped, positive-sense, single-stranded RNA viruses of zoonotic origin. Coronaviruses infect both animals and humans. While the alpha and beta genera are derived from the bat gene pool, the gamma and delta genera are derived from the avian and pig gene pools.

Gammacoronavirus is one of the four genera, Alpha-, Beta-, Gamma-, and Delta-, in the subfamily Orthocoronavirinae of the family Coronaviridae. They are enveloped, positive-sense, single-stranded RNA viruses of zoonotic origin. Coronaviruses infect both animals and humans. While the alpha and beta genera are derived from the bat gene pool, the gamma and delta genera are derived from the avian and pig gene pools.

Human coronavirus 229E is a single-stranded, positive-sense, RNA virus species in the genus Alphacoronavirus of the subfamily Coronavirinae, in the family Coronaviridae, of the order Nidovirales. Along with Human coronavirus OC43, it is responsible for the common cold.

Miniopterus bat coronavirus 1 is a novel enveloped, single-stranded positive-sense RNA virus species in the Alphacoronavirus, or Group 1, genus with a corona-like morphology. It causes severe acute respiratory syndrome in bats. Isolates have not been found in humans.

Rhinolophus bat coronavirus HKU2 is a novel enveloped, single-stranded positive-sense RNA virus species in the Alphacoronavirus, or Group 1, genus with a corona-like morphology.

Scotophilus bat coronavirus 512 is an enveloped, single-stranded positive-sense RNA virus species in the Alphacoronavirus, or Group 1, genus with a corona-like morphology. It was isolated from a Lesser Asiatic Yellow House Bat discovered in southern China.

Positive-sense single-stranded RNA virus type of virus according to Baltimore

A positive-sense single-stranded RNA virus is a virus that uses positive sense, single-stranded RNA as its genetic material. Single stranded RNA viruses are classified as positive or negative depending on the sense or polarity of the RNA. The positive-sense viral RNA genome can also serve as messenger RNA and can be translated into protein in the host cell. Positive-sense ssRNA viruses belong to Group IV in the Baltimore classification. Positive-sense RNA viruses account for a large fraction of known viruses, including many pathogens such as the hepatitis C virus, West Nile virus, dengue virus, and SARS and MERS coronaviruses, as well as less clinically serious pathogens such as the rhinoviruses that cause the common cold.

References

  1. ↑ "ICTV Taxonomy History for Alphacoronavirus 1". ICTV. Retrieved 5 July 2014.
  2. ↑ Thiel V, ed. (2007). Coronaviruses: Molecular and Cellular Biology (1st ed.). Caister Academic Press. ISBN   978-1-904455-16-5.[ page needed ]
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