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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. 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 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 molecules of DNA or RNA that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthocoronavirinae
Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the common cold (which is also caused by other viruses, predominantly rhinoviruses), while more lethal varieties can cause SARS, MERS and COVID-19. In cows and pigs they cause diarrhea, while in mice they cause hepatitis and encephalomyelitis. Coronaviruses constitute the subfamily ''Orthocoronavirinae'', in the family '' Coronaviridae'', order '' Nidovirales'' and realm '' Riboviria''. They are enveloped viruses with a positive-sense single-stranded RNA genome and a nucleocapsid of helical symmetry. The genome size of coronaviruses ranges from approximately 26 to 32 kilobases, one of the largest among RNA viruses. They have characteristic club-shaped spikes that project from their surface, which in electron micrographs create an ima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duplodnaviria
''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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Riboviria
''Riboviria'' is a Realm (virology), realm of viruses that includes all viruses that use a homologous RNA-dependent polymerase for replication. It includes RNA viruses that Genetic code, encode an RNA-dependent RNA polymerase, as well as Pararnavirae, reverse-transcribing viruses (with either RNA or DNA genomes) that encode an Reverse transcriptase, RNA-dependent DNA polymerase. RNA-dependent RNA polymerase (RdRp), also called RNA replicase, produces RNA (ribonucleic acid) from RNA. RNA-dependent DNA polymerase (RdDp), also called reverse transcriptase (RT), produces DNA (deoxyribonucleic acid) from RNA. These enzymes are essential for Viral replication, replicating the viral genome and Transcription (biology), transcribing viral genes into messenger RNA (mRNA) for Translation (biology), translation of viral proteins. ''Riboviria'' was established in 2018 to accommodate all RdRp-encoding RNA viruses and was expanded a year later to also include RdDp-encoding viruses. These two grou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virology
Virology is the Scientific method, scientific study of biological viruses. It is a subfield of microbiology that focuses on their detection, structure, classification and evolution, their methods of infection and exploitation of host (biology), host cell (biology), cells for reproduction, their interaction with host organism physiology and immunity, the diseases they cause, the techniques to isolate and culture them, and their use in research and therapy. The identification of the causative agent of tobacco mosaic disease (TMV) as a novel pathogen by Martinus Beijerinck (1898) is now acknowledged as being the history of virology, official beginning of the field of virology as a discipline distinct from bacteriology. He realized the source was neither a bacterial nor a fungal infection, but something completely different. Beijerinck used the word "virus" to describe the mysterious agent in his 'contagium vivum fluidum' ('contagious living fluid'). Rosalind Franklin proposed the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monodnaviria
''Monodnaviria'' is a Realm (virology), realm of viruses that includes all DNA virus#Group II: ssDNA viruses, single-stranded DNA viruses that Genetic code, encode an HUH-tag, endonuclease of the HUH superfamily that initiates rolling circle replication (RCR) of the circular viral genome. Viruses descended from such viruses are also included in the realm, including certain linear single-stranded DNA (ssDNA) viruses and circular double-stranded DNA (dsDNA) viruses. These atypical members typically replicate through means other than rolling circle replication. ''Monodnaviria'' was established in 2019 and contains four kingdoms: ''Loebvirae'', ''Sangervirae'', ''Trapavirae'', and ''Shotokuvirae''. Viruses in the first three kingdoms infect prokaryotes, and viruses in ''Shotokuvirae'' infect eukaryotes and include the atypical members of the realm. Viruses in ''Monodnaviria'' appear to have come into existence independently multiple times from circular bacterial and archaeal plasmids t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Varidnaviria
''Varidnaviria'' is a realm of viruses that includes all DNA viruses that encode major capsid proteins that contain two vertical jelly roll folds. The major capsid proteins (MCP) form into pseudohexameric subunits of the viral capsid, which stores the viral deoxyribonucleic acid (DNA). The jelly roll folds are vertical, or perpendicular, to the surface of the capsid. Apart from the double jelly roll fold MCP (DJR-MCP), most viruses in the realm share many other characteristics, such as minor capsid proteins (mCP) that has one vertical jelly roll fold, an ATPase that packages viral DNA into the capsid, a DNA polymerase that replicates the viral genome, and capsids that are icosahedral in shape. ''Varidnaviria'' was established in 2019 based on the shared characteristics of the viruses in the realm. There are two kingdoms in the realm: ''Abadenavirae'', which contains all prokaryotic DJR-MCP viruses except tectiviruses, and ''Bamfordvirae'' which contains tectiviruses and al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
SARS-CoV-2
Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) is a strain of coronavirus that causes COVID-19, the respiratory illness responsible for the COVID-19 pandemic. The virus previously had the Novel coronavirus, provisional name 2019 novel coronavirus (2019-nCoV), and has also been called human coronavirus 2019 (HCoV-19 or hCoV-19). First identified in the city of Wuhan, Hubei, China, the World Health Organization designated the outbreak a public health emergency of international concern from January 30, 2020, to May 5, 2023. SARS‑CoV‑2 is a positive-sense single-stranded RNA virus that is Contagious disease, contagious in humans. SARS‑CoV‑2 is a strain of the species ''Betacoronavirus pandemicum'' (SARSr-CoV), as is SARS-CoV-1, the virus that caused the 2002–2004 SARS outbreak. There are animal-borne coronavirus strains more closely related to SARS-CoV-2, the most closely known relative being the BANAL-52 bat coronavirus. SARS-CoV-2 is of Zoonosis, z ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Singelaviria
''Singelaviria'' is a realm of viruses that includes all DNA viruses that encode major capsid proteins that contain a single vertical jelly roll fold. All viruses in ''Singelaviria'' have two major capsid proteins (MCPs) that both have a single jelly roll (SJR) fold. The MCPs form into pseudohexameric subunits of the viral capsid, which stores the viral deoxyribonucleic acid (DNA), and are vertical, or perpendicular, to the surface of the capsid. Apart from the SJR fold MCP (SJR-MCP), viruses in the realm also share a minor capsid protein (mCP) that also has a vertical SJR, an ATPase that packages viral DNA into the capsid, capsids that are icosahedral in shape, and a lipid membrane inside the capsid that surrounds the viral genome. Viruses in ''Singelaviria'' infect archaea that inhabit highly saline environments and bacteria that inhabit high-temperature environments. Their genomes consist of double-stranded DNA that is either linear or circular in shape. Some viruses in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adnaviria
''Adnaviria'' is a Realm (virology), realm of viruses that includes archaeal viruses that have a filamentous virion (i.e. body) and a linear, double-stranded DNA genome. The genome exists in A-form (A-DNA) and encodes a dimeric major capsid protein (MCP) that contains the SIRV2 fold, a type of alpha-helix bundle containing four helices. The virion consists of the genome encased in capsid proteins to form a helical nucleoprotein complex. For some adnaviruses, this helix is surrounded by a lipid membrane called an Viral envelope, envelope. Some contain an additional protein layer between the nucleoprotein helix and the envelope. Complete virions are long and thin and may be flexible or a stiff like a rod. ''Adnaviria'' was established in 2020 after cryogenic electron microscopy showed that the viruses in the realm were related due to a shared MCP, A-DNA, and general virion structure. Viruses in ''Adnaviria'' infect hyperthermophilic and acidophilic archaea, i.e. archaea that inhabit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infectious Agent
In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ. The term ''pathogen'' came into use in the 1880s. Typically, the term ''pathogen'' is used to describe an ''infectious'' microorganism or agent, such as a virus, bacterium, protozoan, prion, viroid, or fungus. Small animals, such as helminths and insects, can also cause or transmit disease. However, these animals are usually referred to as parasites rather than pathogens. The scientific study of microscopic organisms, including microscopic pathogenic organisms, is called microbiology, while parasitology refers to the scientific study of parasites and the organisms that host them. There are several pathways through which pathogens can invade a host. The principal pathways have different episodic time frames, but soil has the longest or most pers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
