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Lambdavirus
''Lambdavirus'' (synonyms ''Lambda-like viruses'', ''Lambda-like phages'', ''Lambda phage group'', ''Lambda phage'') is a genus of viruses in the order ''Caudovirales'', in the family ''Siphoviridae''. Bacteria serve as natural hosts, with transmission achieved through passive diffusion. There are five species in this genus. The genus also includes several unclassified viruses—including the corynephages β and ω, which infect '' Corynebacterium diphtheriae'' and carry the deadly diphtheria toxin.NCBICorynephage beta(species)NCBICorynephage omega(species) Taxonomy The following species are recognized: * ''Enterobacteria virus O276'' * ''Escherichia virus DE3'' * ''Escherichia virus HK629'' * ''Escherichia virus HK630'' * '' Escherichia virus Lambda'' Structure Lambdaviruses are nonenveloped, with a head and tail. The head is about 60 nm in diameter, consisting of 72 capsomers (T=7, levo). Genome All species have been fully sequenced. They range between 42k and 49k nucle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambda Phage
''Enterobacteria phage λ'' (lambda phage, coliphage λ, officially ''Escherichia virus Lambda'') is a bacterial virus, or bacteriophage, that infects the bacterial species ''Escherichia coli'' (''E. coli''). It was discovered by Esther Lederberg in 1950. The wild type of this virus has a temperate life cycle that allows it to either reside within the genome of its host through lysogeny or enter into a lytic phase, during which it kills and lyses the cell to produce offspring. Lambda strains, mutated at specific sites, are unable to lysogenize cells; instead, they grow and enter the lytic cycle after superinfecting an already lysogenized cell. The phage particle consists of a head (also known as a capsid), a tail, and tail fibers (see image of virus below). The head contains the phage's double-strand linear DNA genome. During infection, the phage particle recognizes and binds to its host, ''E. coli'', causing DNA in the head of the phage to be ejected through the tail into the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siphoviridae
''Siphoviridae'' is a family of double-stranded DNA viruses in the order ''Caudovirales''. Bacteria and archaea serve as natural hosts. There are 1,166 species in this family, assigned to 366 genera and 22 subfamilies. The characteristic structural features of this family are a nonenveloped head and noncontractile tail. Structure Viruses in ''Siphoviridae'' are non-enveloped, with icosahedral and head-tail geometries (morphotype B1) or a prolate capsid (morphotype B2), and T=7 symmetry. The diameter is around 60 nm. Members of this family are also characterized by their filamentous, cross-banded, noncontractile tails, usually with short terminal and subterminal fibers. Genomes are double stranded and linear, around 50 kb in length, containing about 70 genes. The guanine/cytosine content is usually around 52%. Life cycle Viral replication is cytoplasmic. Entry into the host cell is achieved by adsorption into the host cell. Replication follows the replicative transposition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corynebacteriophage
A corynebacteriophage (or just corynephage) is a DNA-containing bacteriophage specific for bacteria of genus ''Corynebacterium'' as its host.NCBICorynephages(list) ''Corynebacterium diphtheriae virus''NCBICorynebacterium diphtheriae virus/phage(species) strain Corynebacterium diphtheriae phage (aka Corynephage βNCBICorynephage beta(species) or just β-phage) introduces toxigenicity into strains of ''Corynebacterium diphtheriae'' as it encodes diphtheria toxin, from L. P. Johnson, M. A. Tomai, P. M. Schlievert [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virus
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. 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,Dimmock p. 4 more than 9,000 virus species have been described in detail of the millions of types of viruses in the environment. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. 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 particles, or ''virions'', consisting of (i) the genetic material, i. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caudovirales
''Caudovirales'' is an order of viruses known as the tailed bacteriophages (''cauda'' is Latin for "tail"). Under the Baltimore classification scheme, the ''Caudovirales'' 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 bacteriophages possess a common origin. There are 14 families, 73 subfamilies, 927 genera, and 2,814 species in the order. This makes ''Caudovirales'' the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corynebacterium Diphtheriae
''Corynebacterium diphtheriae'' is the pathogenic bacterium that causes diphtheria. It is also known as the Klebs–Löffler bacillus, because it was discovered in 1884 by German bacteriologists Edwin Klebs (1834–1912) and Friedrich Löffler (1852–1915). The bacteria are usually harmless unless they are infected by a bacteriophage that carries a gene that gives rise to a toxin. This toxin causes the disease. Diphtheria is caused by the adhesion and infiltration of the bacteria into the mucosal layers of the body, primarily affecting the respiratory tract and the subsequent release of an endotoxin. The toxin has a localized effect on skin lesions, as well as a metastatic, proteolytic effects on other organ systems in severe infections. Originally a major cause of childhood mortality, diphtheria has been almost entirely eradicated due to the vigorous administration of the diphtheria vaccination in the 1910s. Diphtheria is no longer transmitted as frequently due to the d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diphtheria Toxin
Diphtheria toxin is an exotoxin secreted by '' Corynebacterium diphtheriae'', the pathogenic bacterium that causes diphtheria. The toxin gene is encoded by a prophageA prophage is a virus that has inserted itself into the genome of the host bacterium. called corynephage β. The toxin causes the disease in humans by gaining entry into the cell cytoplasm and inhibiting protein synthesis. Structure Diphtheria toxin is a single polypeptide chain of 535 amino acids consisting of two subunits linked by disulfide bridges, known as an A-B toxin. Binding to the cell surface of the B subunit (the less stable of the two subunits) allows the A subunit (the more stable part of the protein) to penetrate the host cell. The crystal structure of the diphtheria toxin homodimer has been determined to 2.5 Ångstrom resolution. The structure reveals a Y-shaped molecule consisting of three domains. Fragment A contains the catalytic C domain, and fragment B consists of the T and R domains: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enterobacteria Virus O276
Enterobacteriaceae is a large family of Gram-negative bacteria. It was first proposed by Rahn in 1936, and now includes over 30 genera and more than 100 species. Its classification above the level of family is still a subject of debate, but one classification places it in the order Enterobacterales of the class Gammaproteobacteria in the phylum Pseudomonadota. In 2016, the description and members of this family were emended based on comparative genomic analyses by Adeolu et al. Enterobacteriaceae includes, along with many harmless symbionts, many of the more familiar pathogens, such as ''Salmonella'', ''Escherichia coli'', ''Klebsiella'', and ''Shigella''. Other disease-causing bacteria in this family include ''Enterobacter'' and ''Citrobacter''. Members of the Enterobacteriaceae can be trivially referred to as enterobacteria or "enteric bacteria",as several members live in the intestines of animals. In fact, the etymology of the family is enterobacterium with the suffix to d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
