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Nidovirales
''Nidovirales'' is an order of Viral envelope, enveloped, positive-strand RNA viruses which infect vertebrates and invertebrates. Host organisms include mammals, birds, reptiles, amphibians, fish, arthropods, Mollusca, molluscs, and helminths. The order includes the families ''Coronaviridae'', ''Arteriviridae, Roniviridae,'' ''Tobaniviridae'', and ''Mesoniviridae''. Member viruses have a viral envelope and a Sense (molecular biology), positive-sense, single-stranded RNA, RNA genome which is Five-prime cap, capped and Polyadenylation, polyadenylated. Nidoviruses are named for the Latin ''nidus'', meaning nest, as all viruses in this order produce a 3' co-terminal nested set of subgenomic mRNAs during infection. Virology Structure Nidoviruses have a viral envelope and a positive-sense, single-stranded RNA genome which is capped and polyadenylated. The group expresses structural proteins separately from the nonstructural ones. The structural proteins are encoded at the 3' reg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronaviridae
''Coronaviridae'' is a family (biology), family of Viral envelope, enveloped, positive-strand RNA viruses which infect fish, amphibians, birds, and mammals. The group includes the subfamilies ''Letovirinae,'' ''Orthocoronavirinae'', and ''Pitovirinae''. The members of the subfamily ''Orthocoronavirinae'' are known as Coronavirus, coronaviruses. The viral genome is 26–32 kilobases in length. The particles are typically decorated with large (~20 nm), club- or petal-shaped surface projections (the "peplomers" or "spikes"), which in electron micrographs of spherical particles create an image reminiscent of the solar corona. Virology The 5' and 3' ends of the genome have a Five-prime cap, cap and poly(A) tract, respectively. The viral envelope, obtained by budding through membranes of the endoplasmic reticulum (ER) or Golgi apparatus, invariably contains two virus-specified glycoprotein species, known as the spike (S) and membrane (M) proteins. The coronavirus spike protein, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesoniviridae
''Mesoniviridae'' is a family of enveloped, positive-strand RNA viruses in the order ''Nidovirales'' which infect mosquitoes Mosquitoes, the Culicidae, are a family of small flies consisting of 3,600 species. The word ''mosquito'' (formed by '' mosca'' and diminutive ''-ito'') is Spanish and Portuguese for ''little fly''. Mosquitoes have a slender segmented body, .... The family is named after the size of the genomes relative to other nidoviruses, with ''meso-'' coming from the Greek language, Greek word ''mesos'', which means medium, and -''ni'' being an abbreviation of ''nido''. History The family is relatively new, having only been discovered in 2011. The first virus, which was named ''Nam Dinh virus'', was found in the Vietnamese province of Nam Định Province, Nam Định. The second virus, named ''Cavally virus'', was then found in Côte d'Ivoire. These two viruses were later found to be of the same species. A third member of this first species, named ''Dak Nong ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tobaniviridae
''Tobaniviridae'' is a family of enveloped, positive-strand RNA viruses in the order ''Nidovirales'' which infect vertebrates. The most common host organisms include mammals, fish, and snakes, with some infections observed in other reptiles. The genome size of tobaniviruses ranges from 20 to 32 kilobases. The family is the only member of the suborder ''Tornidovirineae''. Taxonomy The family ''Tobaniviridae'' has four subfamilies and eleven genera: *'' Piscanivirinae'' **'' Bafinivirus'' **'' Oncotshavirus'' *'' Remotovirinae'' **'' Bostovirus'' *'' Serpentovirinae'' ** '' Infratovirus'' ** '' Lyctovirus'' ** '' Pregotovirus'' ** '' Sectovirus'' ** '' Septovirus'' ** '' Sertovirus'' ** '' Vebetovirus'' *'' Torovirinae'' **''Torovirus ''Torovirus'' is a genus of Viral envelope, enveloped, positive-strand RNA viruses in the order ''Nidovirales'' and family ''Tobaniviridae''. They primarily infect vertebrates, especially cattle, pigs, and horses. Diseases associated with this g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arteriviridae
''Arteriviridae'' is a family of enveloped, positive-strand RNA viruses in the order '' Nidovirales'' which infect vertebrates. Host organisms include equids, pigs, Possums, nonhuman primates, and rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...s. The family includes, for example, equine arteritis virus in horses which causes mild-to-severe respiratory disease and reproductive failure, porcine reproductive and respiratory syndrome virus type 1 and type 2 in pigs which causes a similar disease, simian hemorrhagic fever virus which causes a highly lethal fever, lactate dehydrogenase–elevating virus which affects mice, and wobbly possum disease virus. Structure Member viruses are enveloped, spherical, and 45–60 nm in diameter. Genome Arteriviruses hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subgenomic MRNA
Subgenomic mRNAs are essentially smaller sections of the original transcribed template strand. 3' to 5' DNA or RNA During transcription, the original template strand is usually read from the 3' to the 5' end from beginning to end. Subgenomic mRNAs are created when transcription begins at the 3' end of the template strand (or 5' of the to-be-newly synthesized template) and begins to copy towards the 5' end of the template strand before "jumping" to the end of the template and copying the last nucleotides of the 5' end of the template, (finishing the 3' tail for the newly created strand). As a result, the translated strand will have a similar 5' end to varying degrees with the original template (depending on which part of the template the transcription jumped over) and a similar 3' end to the template. 5' to 3' (positive sense) viral RNA Positive-sense (5' to 3') viral RNA which may be directly translated into the desired viral proteins, undergoes a similar process as described ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positive-strand RNA Virus
Positive-strand RNA viruses (+ssRNA viruses) are a group of related viruses that have Sense (molecular biology), positive-sense, single-stranded genomes made of ribonucleic acid. The positive-sense genome can act as messenger RNA (mRNA) and can be directly translation (biology), translated into viral proteins by the host cell, host cell's ribosomes. Positive-strand RNA viruses encode an RNA-dependent RNA polymerase (RdRp) which is used during replication of the genome to synthesize a negative-sense antigenome that is then used as a template to create a new positive-sense viral genome. Positive-strand RNA viruses are divided between the phyla ''Kitrinoviricota'', ''Lenarviricota'', and ''Pisuviricota'' (specifically classes ''Pisoniviricetes'' and ''Stelpaviricetes, Stelpavirictes'') all of which are in the kingdom ''Orthornavirae'' and Realm (virology), realm ''Riboviria''. They are Monophyly, monophyletic and descended from a common RNA virus ancestor. In the Baltimore classi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3C-like Protease
The 3C-like protease (3CLpro) or main protease (Mpro), formally known as C30 endopeptidase or 3-chymotrypsin-like protease, is the main protease found in coronaviruses. It cleaves the coronavirus polyprotein at eleven conserved sites. It is a cysteine protease and a member of the PA clan of proteases. It has a cysteine-histidine catalytic dyad at its active site and cleaves a Gln–( Ser/ Ala/ Gly) peptide bond. The Enzyme Commission refers to this family as SARS coronavirus main proteinase (Mpro; ). The 3CL protease corresponds to coronavirus nonstructural protein 5 (nsp5). The "3C" in the common name refers to the 3C protease (3Cpro) which is a homologous protease found in picornaviruses. Function The 3C-like protease is able to catalytically cleave a peptide bond between a glutamine at position P1 and a small amino acid (serine, alanine, or glycine) at position P1'. The SARS coronavirus 3CLpro can for instance self-cleave the following peptides: The protease is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphibian
Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excluding the amniotes (tetrapods with an amniotic membrane, such as modern reptiles, birds and mammals). All extant taxon, extant (living) amphibians belong to the monophyletic subclass (biology), subclass Lissamphibia, with three living order (biology), orders: Anura (frogs and toads), Urodela (salamanders), and Gymnophiona (caecilians). Evolved to be mostly semiaquatic, amphibians have adapted to inhabit a wide variety of habitats, with most species living in freshwater ecosystem, freshwater, wetland or terrestrial ecosystems (such as riparian woodland, fossorial and even arboreal habitats). Their biological life cycle, life cycle typically starts out as aquatic animal, aquatic larvae with gills known as tadpoles, but some species have devel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyadenylation
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 eukaryotes, polyadenylation is part of the process that produces mature mRNA for translation. In many bacteria, the poly(A) tail promotes degradation of the mRNA. It, therefore, forms part of the larger process of gene expression. The process of polyadenylation begins as the transcription of a gene terminates. The 3′-most segment of the newly made pre-mRNA is first cleaved off by a set of proteins; these proteins then synthesize the poly(A) tail at the RNA's 3′ end. In some genes these proteins add a poly(A) tail at one of several possible sites. Therefore, polyadenylation can produce more than one transcript from a single gene (alternative polyadenylation), similar to alternative splicing. The poly(A) tail is important for the nuclea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helicase
Helicases are a class of enzymes that are vital to all organisms. Their main function is to unpack an organism's genetic material. Helicases are motor proteins that move directionally along a nucleic double helix, separating the two hybridized nucleic acid strands (hence '' helic- + -ase''), via the energy gained from ATP hydrolysis. There are many helicases, representing the great variety of processes in which strand separation must be catalyzed. Approximately 1% of eukaryotic genes code for helicases. The human genome codes for 95 non-redundant helicases: 64 RNA helicases and 31 DNA helicases. Many cellular processes, such as DNA replication, transcription, translation, recombination, DNA repair and ribosome biogenesis involve the separation of nucleic acid strands that necessitates the use of helicases. Some specialized helicases are also involved in sensing viral nucleic acids during infection and fulfill an immunological function. Genetic mutations that affect helicase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNA-dependent RNA Polymerase
RNA-dependent RNA polymerase (RdRp) or RNA replicase is an enzyme that catalyzes the self-replication, replication of RNA from an RNA template. Specifically, it catalyzes synthesis of the RNA strand Complementarity (molecular biology), complementary to a given RNA template. This is in contrast to typical DNA-dependent RNA polymerases, which all organisms use to catalyze the transcription (genetics), transcription of RNA from a DNA template. RdRp is an essential protein encoded in the genomes of most RNA-containing viruses that lack a DNA stage, including SARS-CoV-2. Some eukaryotes also contain RdRps, which are involved in RNA interference and differ structurally from viral RdRps. History Viral RdRps were discovered in the early 1960s from studies on mengovirus and polio virus when it was observed that these viruses were not sensitive to actinomycin D, a drug that inhibits cellular DNA-directed RNA synthesis. This lack of sensitivity suggested the action of a virus-specific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmembrane Protein
A transmembrane protein is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the membrane. They frequently undergo significant conformational changes to move a substance through the membrane. They are usually highly hydrophobic and aggregate and precipitate in water. They require detergents or nonpolar solvents for extraction, although some of them ( beta-barrels) can be also extracted using denaturing agents. The peptide sequence that spans the membrane, or the transmembrane segment, is largely hydrophobic and can be visualized using the hydropathy plot. Depending on the number of transmembrane segments, transmembrane proteins can be classified as single-pass membrane proteins, or as multipass membrane proteins. Some other integral membrane proteins are called monotopic, meaning that they are also permanently attached to the membrane, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
