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Realm (virology)
In virology, realm is the highest taxonomic rank established for viruses by the International Committee on Taxonomy of Viruses (ICTV), which oversees virus taxonomy. Six virus realms are recognized and united by specific Conserved sequence, highly conserved traits: * ''Adnaviria'', which contains archaeal filamentous viruses with A-form double-stranded (ds) DNA genomes encoding a unique alpha-helical major capsid protein; * ''Duplodnaviria'', which contains all dsDNA viruses that encode the HK97-fold major capsid protein; * ''Monodnaviria'', which contains all single-stranded DNA (ssDNA) viruses that encode a HUH-tag, HUH superfamily endonuclease and their descendants; * ''Riboviria'', which contains all RNA viruses that encode RNA-dependent RNA polymerase and all viruses that encode reverse transcriptase; * ''Ribozyviria'', which contains hepatitis delta-like viruses with circular, negative-sense ssRNA genomes; * and ''Varidnaviria'', which contains all dsDNA viruses that en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virus Classification L Pengo Vflip
A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898, more than 16,000 of the millions of List of virus species, virus species have been described in detail. The study of viruses is known as virology, a subspeciality of microbiology. When infected, a host cell is often forced to rapidly produce thousands of copies of the original virus. When not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent viral particles, or ''virions'', consisting of (i) genetic material, i.e., long ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Descent
Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. According to modern evolutionary biology, all living beings could be descendants of a unique ancestor commonly referred to as the last universal common ancestor (LUCA) of all life on Earth. Common descent is an effect of speciation, in which multiple species derive from a single ancestral population. The more recent the ancestral population two species have in common, the more closely they are related. The most recent common ancestor of all currently living organisms is the last universal ancestor, which lived about 3.9 billion years ago. The two earliest pieces of evidence for life on Earth are graphite found to be biogenic in 3.7 billion-year-old metasedimentary rocks discovered in western Greenland and microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia. All currently living organisms on Earth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endonuclease
In molecular biology, endonucleases are enzymes that cleave the phosphodiester bond within a polynucleotide chain (namely DNA or RNA). Some, such as deoxyribonuclease I, cut DNA relatively nonspecifically (with regard to sequence), while many, typically called '' restriction endonucleases'' or ''restriction enzymes'', cleave only at very specific nucleotide sequences. Endonucleases differ from exonucleases, which cleave the ends of recognition sequences instead of the middle (''endo'') portion. Some enzymes known as "exo-endonucleases", however, are not limited to either nuclease function, displaying qualities that are both endo- and exo-like. Evidence suggests that endonuclease activity experiences a lag compared to exonuclease activity. Restriction enzymes are endonucleases from eubacteria and archaea that recognize a specific DNA sequence. The nucleotide sequence recognized for cleavage by a restriction enzyme is called the ''restriction site''. Typically, a restriction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kaposi's Sarcoma
Kaposi's sarcoma (KS) is a type of cancer that can form masses on the skin, in lymph nodes, in the mouth, or in other organs. The skin lesions are usually painless, purple and may be flat or raised. Lesions can occur singly, multiply in a limited area, or may be widespread. Depending on the sub-type of disease and level of immune suppression, KS may worsen either gradually or quickly. Except for classic KS where there is generally no immune suppression, KS is caused by a combination of Immunosuppression, immune suppression (such as due to HIV/AIDS) and infection by Human herpesvirus 8 (HHV8 – also called KS-associated herpesvirus (KSHV)). Classic, endemic, immunosuppression therapy-related (also known as iatrogenic), and epidemic (also known as AIDS-related) sub-types are all described. Classic KS tends to affect older men in regions where KSHV is highly prevalent (Mediterranean, Eastern Europe, Middle East), is usually slow-growing, and most often affects only the legs. Endem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shingles
Shingles, also known as herpes zoster or zona, is a viral disease characterized by a painful skin rash with blisters in a localized area. Typically the rash occurs in a single, wide mark either on the left or right side of the body or face. Two to four days before the rash occurs there may be paresthesia, tingling or local pain in the area. Other common symptoms are fever, headache, and tiredness. The rash usually heals within two to four weeks, but some people develop ongoing neuropathy, nerve pain which can last for months or years, a condition called postherpetic neuralgia (PHN). In those with Immunosuppression, poor immune function the #Disseminated shingles, rash may occur widely. If the rash involves the eye, vision loss may occur. Shingles is caused by the varicella zoster virus (VZV) that also causes chickenpox. In the case of chickenpox, also called varicella, the initial infection with the virus typically occurs during childhood or adolescence. Once the chickenpox ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chickenpox
Chickenpox, also known as varicella ( ), is a highly contagious disease caused by varicella zoster virus (VZV), a member of the herpesvirus family. The disease results in a characteristic skin rash that forms small, itchy blisters, which eventually scab over. It usually starts on the chest, back, and face. It then spreads to the rest of the body. The rash and other symptoms, such as fever, tiredness, and headaches, usually last five to seven days. Complications may occasionally include pneumonia, inflammation of the brain, and bacterial skin infections. The disease is usually more severe in adults than in children. Chickenpox is an airborne disease which easily spreads via human-to-human transmission, typically through the coughs and sneezes of an infected person. The incubation period is 10–21 days, after which the characteristic rash appears. It may be spread from one to two days before the rash appears until all lesions have crusted over. It may also spread through ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herpes Simplex
Herpes simplex, often known simply as herpes, is a viral disease, viral infection caused by the herpes simplex virus. Herpes infections are categorized by the area of the body that is infected. The two major types of herpes are Cold sore, oral herpes and genital herpes, though Herpes simplex#Types of herpes, other forms also exist. Oral herpes involves the face or mouth. It may result in small blisters in groups, often called cold sores or fever blisters, or may just cause a sore throat. Genital herpes involves the genitalia. It may have minimal symptoms or form blisters that break open and result in small ulcers. These typically heal over two to four weeks. Tingling or shooting pains may occur before the blisters appear. Herpes cycles between periods of active disease followed by periods without symptoms. The first episode is often more severe and may be associated with fever, muscle pains, swollen lymph nodes and headaches. Over time, episodes of active disease decrease in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herpesvirales
''Herpesvirales'' is an order of dsDNA viruses (Baltimore group I) with animal hosts, characterised by a common morphology consisting of an icosahedral capsid enclosed in a glycoprotein-containing lipid envelope. Common infections in humans caused by members of this order include cold sores, genital herpes, chickenpox, shingles, and glandular fever. ''Herpesvirales'' is the sole order in the class ''Herviviricetes'', which is the sole class in the phylum ''Peploviricota''. Virology Morphology All members of the order have a virion structure that consists of a DNA core surrounded by an icosahedral capsid composed of 12 pentavalent and 150 hexavalent capsomeres (T = 16). The capsid has a diameter of ~110 nanometers (nm) and is embedded in a proteinaceous matrix called the tegument, which in its turn is enclosed by a glycoprotein-containing lipid envelope with a diameter of about 200 nm. The DNA genome is linear and double stranded, with sizes in the range 125–290 kbp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caudovirales
''Caudoviricetes'' is a class of viruses known as tailed viruses and head-tail viruses (''cauda'' is Latin for "tail"). It is the sole representative of its own phylum, ''Uroviricota'' (from ''ouros'' (ουρος), a Greek word for "tailed" + -viricota). Under the Baltimore classification scheme, the ''Caudoviricetes'' are group I viruses as they have double stranded DNA (dsDNA) genomes, which can be anywhere from 18,000 base pairs to 500,000 base pairs in length. The virus particles have a distinct shape; each virion has an icosahedral head that contains the viral genome, and is attached to a flexible tail by a connector protein. The order encompasses a wide range of viruses, many containing genes of similar nucleotide sequence and function. However, some tailed bacteriophage genomes can vary quite significantly in nucleotide sequence, even among the same genus. Due to their characteristic structure and possession of potentially homologous genes, it is believed these viruse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duplodnaviria Virion Morphology
''Duplodnaviria'' is a realm of viruses that includes all double-stranded DNA viruses that encode the HK97 fold major capsid protein. The HK97 fold major capsid protein (HK97 MCP) is the primary component of the viral capsid, which stores the viral deoxyribonucleic acid (DNA). Viruses in the realm also share a number of other characteristics, such as an icosahedral capsid, an opening in the capsid called a portal, a protease enzyme that empties the inside of the capsid prior to DNA packaging, and a terminase enzyme that packages viral DNA into the capsid. There are three groups of viruses in the realm: caudoviruses, herpesviruses, and the putative group mirusviruses. Caudoviruses are one of the most abundant group of viruses on Earth and are ubiquitous worldwide. They infect prokaryotes and are a major cause of death in them, which contributes to the recycling of organic material in a process called viral shunt. Caudoviruses have been used as model organisms to study biologi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellite (biology)
A satellite is a subviral agent that depends on the coinfection of a host cell with a helper virus for its replication. Satellites can be divided into two major groups: satellite viruses and satellite nucleic acids. Satellite viruses, which are most commonly associated with plants, are also found in mammals, arthropods, and bacteria. They encode structural proteins to enclose their genetic material, which are therefore distinct from the structural proteins of their helper viruses. Satellite nucleic acids, in contrast, do not encode their own structural proteins, but instead are encapsulated by proteins encoded by their helper viruses. The genomes of satellites range upward from 359 nucleotides in length for satellite tobacco ringspot virus RNA (STobRV). Most viruses have the capability to use host enzymes or their own replication machinery to independently replicate their own viral RNA. Satellites, in contrast, are completely dependent on a helper virus for replication. The sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viroid
Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most cause diseases, whose respective economic importance to humans varies widely. A recent metatranscriptomics study suggests that the host diversity of viroids and viroid-like elements is broader than previously thought and that it would not be limited to plants, encompassing even the prokaryotes. The first discoveries of viroids in the 1970s triggered the historically third major extension of the biosphere—to include smaller lifelike entities—after the discoveries in 1675 by Antonie van Leeuwenhoek (of the "subvisible" microorganisms) and in 1892–1898 by Dmitri Iosifovich Ivanovsky and Martinus Beijerinck (of the "submicroscopic" viruses). The unique properties of viroids have been recognized by the International Committee on Taxonomy of Viruses, in creating a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
