Virology, often considered a part of microbiology or of pathology, is the study of organic viruses: their structure and classification, their ways to infect and exploit cells to reproduce and cause disease, the techniques to isolate and culture them, and their potential uses in research and therapy. A researcher in virology is a virologist. An agar plate streaked with microorganisms Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. ... Pathology (from Greek pathos, feeling, pain, suffering; and logos, study of; see also -ology) is the study of the processes underlying disease and other forms of illness, harmful abnormality, or dysfunction. ... A common alternate meaning of virus is computer virus. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ...

Virus structure and classification

A major branch of virology is virus classification. Viruses can be classified according to the host cell they infect: animal viruses, plant viruses, fungal viruses, and bacteriophages (viruses infecting bacteria, which include the most complex viruses). Another classification uses the geometrical shape of their capsid (often a helix or an icosahedron) or the virus's structure (e.g. presence or absence of a lipid envelope). Viruses range in size from about 30 nm to about 450 nm, which means that most of them cannot be seen with light microscopes. The shape and structure of viruses can be studied with electron microscopy, with NMR spectroscopy, and most importantly with X-ray crystallography. Virus classification involves naming and placing viruses into a taxonomic system. ... Plant viruses are viruses affecting plants. ... Divisions Chytridiomycota Zygomycota Glomeromycota Ascomycota Basidiomycota Deuteromycota Fungi (singular fungus) are a kingdom of eukaryotic organisms. ... A bacteriophage (from bacteria and Greek phagein, to eat) is a virus that infects bacteria. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... The outer shell of a virus is called the capsid. ... A helix (pl: helices), from the Greek word έλικας/έλιξ, is a twisted shape like a spring, screw or a spiral (correctly termed helical) staircase. ... An icosahedron noun (plural: -drons, -dra ) is a polyhedron having 20 faces, but usually a regular icosahedron is implied, which has equilateral triangles as faces. ... A polyunsaturated triglyceride. ... To help compare different orders of magnitude this page lists lengths between 10 nm and 100 nm (10-8 and 10-7 m). ... To help compare different orders of magnitude this page lists lengths between 10-7 and 10-6 m (100 nm and 1 µm). ... 1852 microscope Compound microscope made by John Cuff in 1750 A microscope (Greek: micron = small and scopos = aim) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. ... This article does not cite its references or sources. ... It has been suggested that NMR Data Processing be merged into this article or section. ... X-ray crystallography or single-crystal X-ray diffraction is an analytical technique which uses the diffraction pattern produced by bombarding a single crystal with X-rays to solve the crystal structure. ...

The most useful and most widely used classification system distinguishes viruses according to the type of nucleic acid they use as genetic material and the viral replication method they employ to coax host cells into producing more viruses: This article or section does not cite its references or sources. ... Viral replication is the term used by virologists to describe the propagation of biological viruses during the infection process in the target host cells. ...

• DNA viruses (divided into double-stranded DNA viruses and the much less common single-stranded DNA viruses),
• RNA viruses (divided into positive-sense single-stranded RNA viruses, negative-sense single-stranded RNA viruses and the much less common double-stranded RNA viruses),
• reverse transcribing viruses (double-stranded reverse-transcribing DNA viruses and single-stranded reverse-transcribing RNA viruses including retroviruses).

In addition virologists also study subviral particles, infectious entities even smaller than viruses: viroids (naked circular RNA molecules infecting plants), satellites (nucleic acid molecules with or without a capsid that require a helper virus for infection and reproduction), and prions (proteins that can exist in a conformation which induces other protein molecules to assume that same conformation). A DNA virus is a virus belonging to either Group I or Group II of the Baltimore classification system for viruses. ... A DNA virus is a virus that has DNA as its genetic material and does not use an RNA intermediate during replication. ... A DNA virus is a virus that has DNA as its genetic material and does not use an RNA intermediate during replication. ... An RNA virus is a virus that either uses RNA as its genetic material, or whose genetic material passes through an RNA intermediate during replication. ... An RNA virus is a virus that either uses RNA as its genetic material, or whose genetic material passes through an RNA intermediate during replication. ... An RNA virus is a virus that either uses RNA as its genetic material, or whose genetic material passes through an RNA intermediate during replication. ... An RNA virus is a virus that either uses RNA as its genetic material, or whose genetic material passes through an RNA intermediate during replication. ... In biochemistry, a reverse transcriptase, also known as RNA-directed DNA polymerase, is a DNA polymerase enzyme that transcribes single-stranded RNA into double-stranded DNA. Normal transcription involves the synthesis of RNA from DNA, hence reverse transcription is the reverse of this, as it synthesises DNA from RNA. Reverse... An RNA virus is a virus that either uses RNA as its genetic material, or whose genetic material passes through an RNA intermediate during replication. ... ss-RNA RT is the single stranded Ribonucleic acid genome that is present in the HIV virus. ... Genera Alpharetrovirus Betaretrovirus Gammaretrovirus Deltaretrovirus Epsilonretrovirus Lentivirus Spumavirus A retrovirus is any virus belonging to the viral family Retroviridae. ... Families Pospiviroidae Avsunviroidae Viroids are plant pathogens that consist of a short stretch (a few hundred nucleobases) of highly complementary, circular, single-stranded RNA without the protein coat that is typical for viruses. ... Groups Satellite viruses Satellite nucleic acids Satellites are subviral agents composed of nucleic acids; they depend for their multiplication on coinfection of a host cell with a helper virus. ... A prion (IPA: .[1][2] ) — short for proteinaceous infectious particle that lacks nucleic acid (by analogy to virion) — is a type of infectious agent made only of protein. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ...

The latest report by the International Committee on Taxonomy of Viruses (2005) lists 5450 viruses, organized in over 2,000 species, 287 genera, 73 families and 3 orders. This page is a candidate to be copied to Wikisource. ...

The taxa in virology are not necessarily monophyletic. In fact, the evolutionary relationships of the various virus groups remain unclear, and three hypotheses regarding their origin exist: A taxon (plural taxa), or taxonomic unit, is a grouping of organisms (named or unnamed). ... In phylogenetics, a group is monophyletic (Greek: of one stem) if all organisms in that group are known to have developed from a common ancestral form, and all descendants of that form are included in the group. ...

1. Viruses arose from non-living matter, separately from and in parallel to other life forms, possibly in the form of self-reproducing RNA ribozymes similar to viroids.
2. Viruses arose from earlier, more competent cellular life forms that became parasites to host cells and subsequently lost most of their functionality; examples of such tiny parasitic prokaryotes are Mycoplasma and Nanoarchaea.
3. Viruses arose as parts of the genome of cells, most likely transposons or plasmids, that acquired the ability to "break free" from the host cell and infect other cells.

It is of course possible that different alternatives apply to different virus groups. This article or section does not adequately cite its references or sources. ... // A ribozyme (from ribonucleic acid enzyme, also called RNA enzyme or catalytic RNA) is an RNA molecule that catalyzes a chemical reaction. ... Families Pospiviroidae Avsunviroidae Viroids are plant pathogens that consist of a short stretch (a few hundred nucleobases) of highly complementary, circular, single-stranded RNA without the protein coat that is typical for viruses. ... Species M. genitalium M. hominis M. pneumoniae etc. ... Binomial name Nanoarchaeum equitans Nanoarchaeum equitans is a species of tiny microbe, discovered in 2002 in a hydrothermal vent off the coast of Iceland by Karl Stetter. ... Transposons are sequences of DNA that can move around to different positions within the genome of a single cell, a process called transposition. ... Figure 1: Schematic drawing of a bacterium with plasmids enclosed. ...

Of particular interest here is mimivirus, a giant virus that infects amoebae and carries much of the molecular machinery traditionally associated with bacteria. Is it a simplified version of a parasitic prokaryote, or did it originate as a simpler virus that acquired genes from its host? Mimivirus is a viral genus containing a single identified species named Acanthamoeba polyphaga mimivirus (APMV). ... Subgroups Mycetozoa(slime moulds) Archamoebae    Pelobiontida    Entamoebida Gymnamoebia Various others The Amoebozoa are a major group of amoeboid protozoa, including the majority that move by means of internal cytoplasmic flow. ...

While viruses reproduce and evolve, they don't engage in metabolism and depend on a host cell for reproduction. The often-debated question of whether they are alive or not is a matter of definition that does not affect the biological reality of viruses. Overview of the citric acid cycle The citric acid cycle, one of the central metabolic pathways in aerobic organisms. ...

Viral diseases and host defenses

One main motivation for the study of viruses is the fact that they cause many important infectious diseases, among them the common cold, influenza, rabies, measles, many forms of diarrhea, hepatitis, yellow fever, polio, smallpox and AIDS. Some viruses, known as oncoviruses, contribute to certain forms of cancer; the best studied example is the association between Human papillomavirus and cervical cancer. Some subviral particles also cause disease: Kuru and Creutzfeldt-Jakob disease are caused by prions, and hepatitis D is due to a satellite virus. // Acute viral nasopharyngitis, often known as the common cold, is a mild viral infectious disease of the upper respiratory system (nose and throat). ... Influenza, commonly known as the flu, is an infectious disease of birds and mammals caused by an RNA virus of the family Orthomyxoviridae (the influenza viruses). ... Types 5-7 on the Bristol Stool Chart are often associated with diarrhea Diarrhea (in American English) or diarrhoea (in British English) is a generally unpleasant condition in which the sufferer has frequent watery, loose bowel movements (from the ancient Greek word διαρροή = leakage; literally meaning to run through). Acute infectious... Hepatitis is inflammation of the liver. ... This article is about the disease. ... Smallpox (also known by the Latin names Variola or Variola vera) is a highly contagious disease unique to humans. ... This article is about the syndrome. ... An oncovirus is a virus associated with cancer. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these cells to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ... HPV redirects here. ... Cervical cancer is a malignancy of the cervix. ... Kuru (also known as laughing sickness due to the outbursts of laughter that mark its second phase) was first noted in New Guinea in the early 1900s. ... Creutzfeldt-Jakob disease (CJD) is a very rare and incurable degenerative neurological disorder (brain disease) that is ultimately fatal. ... Hepatitis D is a disease caused by a small circular RNA virus (Hepatitis delta virus); this virus is replication defective and therefore cannot propagate in the absence of another virus. ...

The study of the manner in which viruses cause disease is viral pathogenesis. The degree to which a virus causes disease is its virulence. Viral pathogenesis is the study of how biological viruses cause diseases in their target hosts, usually carried out at the cellular or molecular level. ... Virulence is either the relative pathogenicity or the relative ability to do damage to the host of an infectious agent. ...

When the immune system of a vertebrate encounters a virus, it produces specific antibodies which bind to the virus and mark it for destruction. The presence of these antibodies is often used to determine whether a person has been exposed to a given virus in the past, with tests such as ELISA. Vaccinations protect against viral diseases, in part, by eliciting the production of antibodies. Specifically constructed monoclonal antibodies can also be used to detect the presence of viruses, with a technique called fluorescence microscopy. A scanning electron microscope image of a single lymphocyte, a component of the human immune system A poop system is a collection of mechanisms within an organism that protect against infection by identifying and killing pathogens. ... Classes and Clades See below Male and female Superb Fairy-wren Vertebrates are members of the subphylum Vertebrata (within the phylum Chordata), specifically, those chordates with backbones or spinal columns. ... Schematic of antibody binding to an antigen An antibody or immunoglobulin is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects like bacteria and viruses. ... Elisa portrayed on the cover of her album Pearl Days. ... Vaccination is the process of administering weakened or dead pathogens to a healthy person or animal, with the intent of conferring immunity against a targeted form of a related disease agent. ... // Monoclonal antibodies (mAb) are antibodies that are identical because they were produced by one type of immune cell and are all clones of a single parent cell. ... Microscopy is any technique for producing visible images of structures or details too small to otherwise be seen by the human eye. ...

A second defense of vertebrates against viruses, cell-mediated immunity, involves immune cells known as T cells: the body's cells constantly display short fragments of their proteins on the cell's surface, and if a T cell recognizes a suspicious viral fragment there, the host cell is destroyed and the virus-specific T-cells proliferate. This mechanism is jump-started by certain vaccinations. Cell-mediated immunity is an immune response that does not involve antibodies but rather involves the activation of macrophages and NK-cells, the production of antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. ... White Blood Cells is also the name of a White Stripes album. ... T cells are a subset of lymphocytes that play a large role in the immune response. ...

RNA interference, an important cellular mechanism found in plants, animals and many other eukaryotes, most likely evolved as a defense against viruses. An elaborate machinery of interacting enzymes detects double-stranded RNA molecules (which occur as part of the life cycle of many viruses) and then proceeds to destroy all single-stranded versions of those detected RNA molecules. Figure 1. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista Alternative Phylogeny Unikonta    Opisthokonta    Amoebozoa Bikonta    Apusozoa    Cabozoa       Rhizaria       Excavata    Corticata       Archaeplastida       Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms with a complex cell or cells, where the genetic material is organized into a membrane-bound nucleus or nuclei. ...

Every lethal viral disease presents a paradox: killing its host is obviously of no benefit to the virus, so how and why did it evolve? Today it is believed that most viruses are relatively benign in their natural host; the lethal viral diseases are explained as resulting from an "accidental" jump of the virus from a species in which it is benign to a new one that is not accustomed to it (see zoonosis). For example, serious influenza viruses probably have pigs or birds as their natural host, and HIV is thought to derive from the benign monkey virus SIV. Zoonosis (pronounced as zoo-on-no-sis) is any infectious disease that may be transmitted from animals, both wild and domestic, to humans. ... Human immunodeficiency virus (HIV) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS), a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections. ... Simian immunodeficiency virus (SIV) is a retrovirus that is found, in numerous strains, in primates; the strains infecting humans are HIV-1 and HIV-2, the viruses that cause AIDS. The origin of HIV is now generally attributed to SIV from African primates. ...

While it has been possible to prevent (certain) viral diseases by vaccination for a long time, the development of antiviral drugs to treat viral diseases is a comparatively recent development. The first such drug was interferon, a substance that is naturally produced by certain immune cells when an infection is detected, thus stimulating other parts of the immune system. Antiviral drugs are a class of medication used specifically for treating viral infections. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

Molecular biology research and viral therapy

Bacteriophages, the viruses which infect bacteria, can be relatively easily grown as viral plaques on bacterial cultures. Bacteriophages occasionally move genetic material from one bacterial cell to another in a process known as transduction, and this horizontal gene transfer is one reason why they served as a major research tool in the early development of molecular biology. The genetic code, the function of ribozymes, the first recombinant DNA and early genetic libraries were all arrived at using bacteriophages. Certain genetic elements derived from viruses, such as highly effective promoters, are commonly used in molecular biology research today. A bacteriophage (from bacteria and Greek phagein, to eat) is a virus that infects bacteria. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... A viral plaque is a visible structure formed within a cell culture, such as bacterial cultures within some nutrient medium (e. ... A microbiological culture is a way to determine the cause of infectious disease by letting the agent multiply (reproduce) in predetermined media. ... Transduction is the process by which bacterial DNA is moved from one bacterium to another by a virus. ... Horizontal gene transfer (HGT), also Lateral gene transfer (LGT), is any process in which an organism transfers genetic material to another cell that is not its offspring. ... Molecular biology is the study of biology at a molecular level. ... RNA codons. ... // A ribozyme (from ribonucleic acid enzyme, also called RNA enzyme or catalytic RNA) is an RNA molecule that catalyzes a chemical reaction. ... Recombinant deoxyribonucleic acid(rDNA) is an artificial DNA sequence resulting from the combining of two other DNA sequences in a plasmid. ... In molecular biology, a library is a collection of molecules in a stable form that represents some aspect of an organism. ... A promoter is a DNA sequence that contains the information, in the form of DNA sequences, that permits the proper activation or repression of the gene which it controls, i. ...

Growing animal viruses outside of the living host animal is more difficult. Classically, fertilized chicken eggs have often been used, but cell cultures are increasingly employed for this purpose today. Epithelial cells in culture, stained for keratin (red) and DNA (green) Cell culture is the term applied when cells are grown in a synthetic environment. ...

Since viruses that infect eukaryotes need to transport their genetic material into the host cell's nucleus, they are attractive tools for introducing new genes into the host (known as transformation or transfection), and this approach of using viruses as gene vectors is being pursued in the gene therapy of genetic diseases. An obvious problem to be overcome in viral gene therapy is the rejection of the transforming virus by the immune system. Kingdoms Animalia - Animals Fungi Plantae - Plants Protista Alternative Phylogeny Unikonta    Opisthokonta    Amoebozoa Bikonta    Apusozoa    Cabozoa       Rhizaria       Excavata    Corticata       Archaeplastida       Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms with a complex cell or cells, where the genetic material is organized into a membrane-bound nucleus or nuclei. ... The eukaryotic cell nucleus. ... Transformation is the genetic alteration of a cell resulting from the introduction, uptake and expression of foreign genetic material (DNA or RNA). ... Introducing DNA into eukaryotic cells, such as animal cells, is called transfection. ... Gene therapy is the insertion of genes into an individuals cells and tissues to treat a disease, and hereditary diseases in particular. ...

Oncolytic viruses are viruses that preferably infect cancer cells. While early efforts to employ these viruses in the therapy of cancer failed, there have been reports in 2005 and 2006 of encouraging preliminary results.[1] An oncolytic virus is a virus used to treat cancer due to their ability to specifically infect cancer cells, while leaving normal cells unharmed. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these cells to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ...

Other uses of viruses

A new application of genetically engineered viruses in nanotechnology was recently described; seeVirus#Materials science and nanotechnology. Buckminsterfullerene C60, also known as the buckyball, is the simplest of the carbon structures known as fullerenes. ... Groups I: dsDNA viruses II: ssDNA viruses III: dsRNA viruses IV: (+)ssRNA viruses V: (-)ssRNA viruses VI: ssRNA-RT viruses VII: dsDNA-RT viruses A virus is a microscopic particle (ranging in size from 20 - 300 nm) that can infect the cells of a biological organism. ...

History

A very early form of vaccination known as variolation was developed several thousand years ago in China. It involved the application of materials from smallpox sufferers in order to immunize others. In 1796 Edward Jenner used cowpox to successfully immunize a young boy against smallpox, and this practice was widely adopted. Vaccinations against other viral diseases followed, including the successful rabies vaccination by Louis Pasteur in 1886. The nature of viruses however was not clear to these researchers. Obsolete: inoculation against smallpox using material from a vesicle or lesion of a person with smallpox. ... Smallpox (also known by the Latin names Variola or Variola vera) is a highly contagious disease unique to humans. ... Portrait of Edward Jenner Edward Jenner, FRS, (May 17, 1749 – January 26, 1823) was an English country doctor who studied nature and his natural surroundings from childhood and practiced medicine in Berkeley, Gloucestershire, England. ... Cowpox is a disease of the skin caused by a virus (Cowpox virus) that is related to the Vaccinia virus. ... Louis Pasteur (December 27, 1822 – September 28, 1895) was a French microbiologist and chemist. ...

In 1892 Dimitri Ivanovski showed that a disease of tobacco plants, tobacco mosaic disease, could be transmitted by extracts that were passed through filters fine enough to exclude even the smallest known bacteria. In 1898 Martinus Beijerinck, also working on tobacco plants, found that this "filterable agent" grew in the host and was thus not a mere toxin. The question of whether the agent was a "living fluid" or a particle was however still open. Dmitry Iosifovich Ivanovsky (1864-1920) was a Russian-Ukrainian biologist who was the first to discover viruses (1892). ... Species Nicotiana acuminata Nicotiana alata Nicotiana attenuata Nicotiana benthamiana Nicotiana clevelandii Nicotiana excelsior Nicotiana forgetiana Nicotiana glauca Nicotiana glutinosa Nicotiana langsdorffii Nicotiana longiflora Nicotiana obtusifolia Nicotiana paniculata Nicotiana plumbagifolia Nicotiana quadrivalvis Nicotiana repanda Nicotiana rustica Nicotianasuaveolens Nicotiana sylvestris Nicotiana tabacum Nicotiana tomentosa Ref: ITIS 30562 as of August 26, 2005... The Tobacco mosaic virus (TMV) is an RNA virus that infects plants, especially tobacco and other members of the family Solanaceae, showing characteristic patterns (mottling and discoloration) on the leaves (thus the name). ... Martinus Willem Beijerinck (March 16, 1851 - January 1, 1931) was a Dutch microbiologist and botanist. ... The venom of the black widow spider is a potent latrotoxin. ...

In 1903 it was suggested for the first time that transduction by viruses might cause cancer. Such an oncovirus in chickens was described by Francis Peyton Rous in 1911; it was later called Rous sarcoma virus 1 and understood to be a retrovirus. Several other cancer-causing retroviruses have since been described. Francis Peyton Rous (October 5, 1879, Texas – February 16, 1970, New York City) was an American pathologist whose discovery of cancer-inducing viruses earned him a share of the Nobel Prize for Physiology or Medicine in 1966. ... Rous sarcoma virus was discovered in 1911 by Peyton Rous, by injecting cell free extract of chicken tumour into healthy chickens. ...

The existence of viruses that infect bacteria was first recognized by Frederick Twort in 1911, and, independently, by Felix d'Herelle in 1917. Since bacteria could be grown easily in culture, this led to an explosion of virology research. An important investigator in this area, Max Delbrück, described the basic life cycle of a virus in 1937: rather than "growing", a virus particle is assembled from its constituent pieces in one step; eventually it leaves the host cell to infect other cells. The Hershey-Chase experiment in 1952 showed that only DNA and not protein enters a bacterial cell upon infection with bacteriophage T2. Transduction of bacteria by bacteriophages was first described in the same year. This article belongs in one or more categories. ... Félix dHerelle (April 25, 1873 – February 22, 1949), French-Canadian microbiologist, one of the discoverers of bacteriophages (small viruses that only attack and kill bacteria), and inventor of phage therapy. ... Max Delbrück (September 4, 1906 - March 9, 1981) was a German biologist. ... The Hershey-Chase experiment was a series of experiments conducted in 1952 by Alfred Hershey and Martha Chase that identified DNA to be the genetic material of phages and, ultimately, of all organisms. ... Enterobacteria phage T2 is a virulent bacteriophage of the T4-like viruses genus, in the family Myoviridae. ... Transduction is the process by which bacterial DNA is moved from one bacterium to another by a virus. ...

While plant viruses and bacteriophages can be grown comparatively easily, animal viruses normally require a living host animal, which complicates their study immensely. In 1931 it was shown that influenza virus could be grown in fertilized chicken eggs, a method that is still used today to produce vaccines. In 1937, Max Theiler managed to grow the yellow fever virus in chicken eggs and produced a vaccine from an attenuated virus strain; this vaccine saved millions of lives and is still being used today. Negatively stained flu virions. ... Max Theiler (January 30, 1899 – August 11, 1972) was a South African virologist, he was awarded the Nobel Prize in Physiology or Medicine in 1951 for developing a vaccine for yellow fever. ...

In 1949 John F. Enders, Thomas Weller and Frederick Robbins reported that they had been able to grow poliovirus in cultured human embryonal cells, the first significant example of an animal virus grown outside of animals and chicken eggs. This work aided Jonas Salk in deriving a polio vaccine from killed polio viruses; this vaccine was shown to be effective in 1955. John Franklin Enders was born in West Hartford, Connecticut February 10, 1887. ... Dr. Thomas Huckle Weller (born June 15, 1915) was an American virologist. ... Frederick Chapman Robbins (August 25, 1916 – August 4, 2003) was an American pediatrician and virologist. ... This article is about the virus. ... Jonas Edward Salk (October 28, 1914 – June 23, 1995) was an American physician and researcher, best known for the development of the first polio vaccine (the eponymous Salk vaccine). ...

The first virus which could be crystalized and whose structure could therefore be elucidated in detail was tobacco mosaic virus (TMV), the virus that had been studied earlier by Ivanovski and Beijerink. In 1935, Wendell Stanley achieved its crystallization for electron microscopy and showed that it remains active even after crystallization. Clear X-ray diffraction pictures of the crystallized virus were obtained by Bernal and Fankuchen in 1941. Based on such pictures, Rosalind Franklin proposed the full structure of the tobacco mosaic virus in 1955. Also in 1955, Heinz Fraenkel-Conrat and Robley Williams showed that purified TMV RNA and its capsid (coat) protein can assemble by themselves to form functional virii, suggesting that this simple mechanism is likely the natural assembly mechanism within the host cell. Quartz crystal Copper(II) sulfate and iodine crystal Synthetic bismuth crystal Insulin crystals Gallium, a metal that easily forms large single crystals A huge monocrystal of potassium dihydrogen phosphate grown from solution by Saint-Gobain for the megajoule laser of CEA. In chemistry and mineralogy, a crystal is a solid... The Tobacco mosaic virus (TMV) is an RNA virus that infects plants, especially tobacco and other members of the family Solanaceae, showing characteristic patterns (mottling and discoloration) on the leaves (thus the name). ... Wendell Meredith Stanley (August 16, 1904 – June 15, 1971) was an American biochemist, virologist and Nobel prize laureate. ... This article does not cite its references or sources. ... X-ray crystallography is a technique in crystallography in which the pattern produced by the diffraction of x-rays through the closely spaced lattice of atoms in a crystal is recorded and then analyzed to reveal the nature of that lattice. ... Rosalind Elsie Franklin (25 July 1920 – 16 April 1958) was an English-born physical chemist and crystallographer who made important contributions to the understanding of the fine structures of DNA, viruses, coal and graphite. ... Heinz Ludwig Fraenkel-Conrat (July 29, 1910 – April 10, 1999) was a biochemist, famous for his viral research. ... Robley Cook Williams (1908 - January 3, 1995) was an early biophysicist and virologist. ... This article or section does not adequately cite its references or sources. ... The outer shell of a virus is called the capsid. ...

In 1963, the Hepatitis B virus was discovered by Baruch Blumberg who went on to construct a vaccine against Hepatitis B. Hepatitis B is a disease of the liver and is caused by the Hepatitis B virus (HBV), a member of the Hepadnavirus family[1] and one of several unrelated viral species which cause viral hepatitis. ... Baruch Samuel Blumberg (born 1925) is a American scientist and recipient of the 1976 Nobel Prize in Medicine for discoveries concerning new mechanisms for the origin and dissemination of infectious diseases. ...

In 1965, Howard Temin described the first retrovirus: a RNA-virus that was able to insert its genome in the form of DNA into the host's genome. Reverse transcriptase, the key enzyme that retroviruses use to translate their RNA into DNA, was first described in 1970, independently by Howard Temin and David Baltimore. The first retrovirus infecting humans was identified by Robert Gallo in 1974. Later it was found that reverse transcriptase is not specific to retroviruses; retrotransposons which code for reverse transcriptase are abundant in the genomes of all eukaryotes. About 10-40% of the human genome derives from such retrotransposons. Howard Martin Temin (1934 - 1994) was a U.S. geneticist. ... Genera Alpharetrovirus Betaretrovirus Gammaretrovirus Deltaretrovirus Epsilonretrovirus Lentivirus Spumavirus A retrovirus is any virus belonging to the viral family Retroviridae. ... In biochemistry, a reverse transcriptase, also known as RNA-directed DNA polymerase, is a DNA polymerase enzyme that transcribes single-stranded RNA into double-stranded DNA. Normal transcription involves the synthesis of RNA from DNA, hence reverse transcription is the reverse of this, as it synthesises DNA from RNA. Reverse... David Baltimore (b. ... Dr. Robert C. Gallo Robert Charles Gallo (born March 23, 1937) is a U.S. biomedical researcher. ... Retrotransposons are genetic elements than can amplify themselves in a genome and are ubiquitous components of the DNA of many eukaryotic organisms. ...

In 1975 the functioning of oncoviruses was clarified considerably. Until that time, it was thought that these viruses carried certain genes called oncogenes which, when inserted into the host's genome, would cause cancer. Michael Bishop and Harold Varmus showed that the oncogene of Rous sarcoma virus is in fact not specific to the virus but is contained in healthy animals of many species. The oncovirus can switch this pre-existing benign proto-oncogene on, turning it into a true oncogene. An oncogene is a modified gene that increases the malignancy of a tumor cell. ... J. Michael Bishop (born February 22, 1936) is an American immunologist and microbiologist who won the 1989 Nobel Prize in Physiology or Medicine. ... Harold E. Varmus was a co-recipient (along with J. Michael Bishop) of the 1989 Nobel Prize in Physiology or Medicine for discovery of the cellular origin of retroviral oncogenes. ...

1976 saw the first recorded outbreak of Ebola hemorrhagic fever, a highly lethal virally transmitted disease. Species Ivory Coast ebolavirus Reston ebolavirus Sudan ebolavirus Zaire virus Ebola hæmorrhagic fever (EHF — alternatively Ebola hemorrhagic fever; commonly referred to as simply Ebola) is a recently identified, severe, often fatal infectious disease occurring in humans and some primates caused by the Ebola virus. ...

In 1977, Frederick Sanger achieved the first complete sequencing of the genome of any organism, a bacteriophage. In the same year, Richard Roberts and Phillip Sharp independently showed that the genes of adenovirus contain introns and therefore require gene splicing. It was later realized that almost all genes of eukaryotes have introns as well. Frederick Sanger, OM, CH, CBE, FRS (born 13 August 1918) is an English biochemist and a two time Nobel laureate in Chemistry. ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... Richard J. Roberts (b. ... Phillip Allen Sharp (born 1944), U.S. geneticist and molecular biologist; co-discovered gene splicing; shared the 1993 Nobel Prize in Physiology or Medicine with Richard J. Roberts for the discovery that genes in eukaryotes are not contiguous strings but contain introns, and that the splicing of messenger RNA to... Genera Mastadenovirus Aviadenovirus Atadenovirus Siadenovirus Adenoviruses are viruses of the family Adenoviridae. ... Diagram of the location of introns and exons within a gene. ... Genetic engineering, genetic modification (GM), and gene splicing (once in widespread use but now deprecated) are terms for the process of manipulating genes in an organism, usually outside of the organisms normal reproductive process. ...

A world-wide vaccination campaign lead by the UN World Health Organization lead to the eradication of smallpox in 1979. The World Health Organization (WHO) is a specialized agency of the United Nations that acts as a coordinating authority on international public health, headquartered in Geneva, Switzerland. ...

In 1982, Stanley Prusiner discovered prions and showed that they cause scrapie. Stanley B. Prusiner, M.D., a Professor of Neurology and Biochemistry at the University of California, San Francisco, was awarded the Nobel Prize in physiology or medicine in 1997 for his discovery of prions a class of infectious self-reproducing agents composed of protein. ... A prion (IPA: .[1][2] ) — short for proteinaceous infectious particle that lacks nucleic acid (by analogy to virion) — is a type of infectious agent made only of protein. ... Scrapie is a fatal, degenerative disease that affects the nervous systems of sheep and goats. ...

The first cases of AIDS were reported in 1981, and HIV, the retrovirus causing it, was identified in 1983 by Robert Gallo and Luc Montagnier. Tests detecting HIV infection by detecting the presence of HIV antibody were developed. Subsequent tremendous research efforts turned HIV into the best studied virus. Human Herpes Virus 8, the cause of Kaposi's sarcoma which is often seen in AIDS patients, was identified in 1994. Several anti-retroviral drugs were developed in the late 1990s, decreasing AIDS mortality dramatically in developed countries. Human immunodeficiency virus (HIV) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS), a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections. ... Dr. Robert C. Gallo Robert Charles Gallo (born March 23, 1937) is a U.S. biomedical researcher. ... Luc Montagnier (born 1932 in Chabris, France) is a French virologist. ... Kaposis sarcoma-associated herpesvirus (KSHV) is the eighth human herpesvirus; its formal name according to the International Committee on Taxonomy of Viruses is HHV-8. ...

The first attempts at gene therapy involving viral vectors began in the early 1980s, when retroviruses were developed that could insert a foreign gene into the host's genome. They contained the foreign gene but did not contain the viral genome and therefore could not reproduce. Tests in mice were followed by tests in humans, beginning in 1989. The first human studies tried to correct the genetic disease severe combined immunodeficiency (SCID), but clinical success was limited. In the period from 1990 to 1995, gene therapy was tried on several other diseases and with different viral vectors, but it became clear that the initially high expectations were overstated. In 1999 a further setback occurred when 17-year-old Jesse Gelsinger died in a gene therapy trial. He suffered a severe immune response after having received an adenovirus vector. Success in the gene therapy of two cases of X-linked SCID was reported in 2000.^[1] Gene therapy is the insertion of genes into an individuals cells and tissues to treat a disease, and hereditary diseases in particular. ... Severe Combined Immunodeficiency, or SCID, is a genetic disorder in which both arms (B cells and T cells) of the adaptive immune system are crippled, due to a defect in one of several possible genes. ... Jesse Gelsinger was the first patient ever to die in clinical trials for gene therapy. ... Genera Mastadenovirus Aviadenovirus Atadenovirus Siadenovirus Adenoviruses are viruses of the family Adenoviridae. ... Severe Combined Immunodeficiency, or SCID, is a genetic disorder in which both arms (B cells and T cells) of the adaptive immune system are crippled, due to a defect in one of several possible genes. ...

The giant mimivirus, in some sense an intermediate between tiny prokaryotes and ordinary viruses, was described in 2003 and sequenced in 2004. Mimivirus is a viral genus containing a single identified species named Acanthamoeba polyphaga mimivirus (APMV). ... DNA sequencing is the process of determining the nucleotide order of a given DNA fragment, called the DNA sequence. ...

Two vaccines protecting against several cervical cancer-causing strands of human papillomavirus (HPV) were released in 2006. Cervical cancer is a malignancy of the cervix. ... HPV redirects here. ...

See also

• Virus
• Virus classification
• List of viruses
• List of viral diseases
• Important publications in virology
• Wikipedia:WikiProject Viruses

Groups I: dsDNA viruses II: ssDNA viruses III: dsRNA viruses IV: (+)ssRNA viruses V: (-)ssRNA viruses VI: ssRNA-RT viruses VII: dsDNA-RT viruses A virus is a microscopic particle (ranging in size from 20 - 300 nm) that can infect the cells of a biological organism. ... Virus classification involves naming and placing viruses into a taxonomic system. ... This is a list of biological viruses, and types of viruses. ... Human infectious diseases grouped by causative agent and alphabetically arranged. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

References

1. ^ Zeger Debyser. A Short Course on Virology / Vectorology / Gene Therapy, Current Gene Therapy, 2003, 3, 495-499

External links and sources

• David Sander: All the Virology on the WWW - collection of links, pictures, lecture notes
• Samuel Baron (ed.) Medical Microbiology, 4th ed., Section 2: Virology (freely searchable online book)
• Coffin, Hughes, Varmus. Retroviruses (freely searchable online book)
• Origins of Virology, from Microbiology at the University of Leicester
• The Virology Time Machine, from Microbiology at the University of Leicester
• Timeline of the history of virology, from the Washington University in St. Louis.
• Wong's Virology.