The Viral genome is a small infectious agent that can replicate only in cells viruses living body. Virus can be from plants and animals, to infect all types of organisms from archaea and bacteria. 1892 article Dimitri Ivanovski, in the detection of tobacco mosaic virus in 1898 Martinus bay d link and tobacco plants infected, there are several million people of various types to explain the non-bacterial pathogens, about 5000 virus, and is described in detail. Virus is present in all ecosystems on Earth most, are the most common type of biological entity. Study of the virus is known as a sub-specialty virology and microbiology.
(Virion is also called) is the virus particle, consists of three parts or two: long molecules carry I), the genetic information in the genetic material made of RNA or DNA; protein layer that protects II), these genes, in some cases lipid envelope that surrounds the coat of ⅲ) extracellular proteins. From the form of the icosahedron and simple helical shape of the virus range of more complex structures. Is about percent of average size average viruses, bacteria. Most viruses, too small to be directly observed with an optical microscope.
In the history of the evolution of life, the origin of the virus is unknown: others may have evolved from the bacteria several possible to be able to move between cells, evolved from the plasmid portion of the DNA There is sex. In evolution, viruses are an important means of horizontal gene transfer to increase the genetic diversity. As they carry genetic material, the virus is considered by some to be reproduced in the form of life will evolve by natural selection. However, (for example, cell structure) is not a main character, which is usually considered, they would be required to count life. As owns a part but not all of these properties, they have been described as “organisms at the end of life” virus.
As aphids is transmitted to plants from plant by insects that it is possible to feed the sap of plants by blood-sucking insects is carried virus in animal virus to spread to be a plant virus is large, in a variety of ways. It is known as the bearing organisms vectors of these diseases. Influenza virus is spread by sneezing and coughing. Feces common cause rotavirus and norovirus, viral gastroenteritis, – It has been sent by the oral route, it enters the body in the water and food, are passed from person to person by contact. HIV is one of the virus or send some by exposure to infected blood through sexual contact. range of host cells capable of viruses infection, called “host range” thereof. Virus If it is possible many kinds are infected widely it, or may be narrowed.
Usually, remove the infecting virus, viral infection in animals to induce an immune response. The immune response can be produced a vaccine for providing adaptive immune artificially certain viral infections. However, some viruses, such as hepatitis and AIDS as a cause of these, you might want to avoid the immune response of these, leading to chronic infection. Antibiotics have no effect on the virus, antiviral drug some have been developed.
Pasteur was not able to guess the pathogen too small to find the cause of rabies, to be detected by using a microscope. 1884, I have invented a filter having microbiologist Charles Chambellan of France, the pores smaller than bacteria. Thus, it is possible to pass a solution containing bacteria through the filter, to remove from the solution entirely. 1892, in order to study what now known as tobacco mosaic virus, biologist Dmitry Ivanovsky in Russia was using this filter. In his experiments, after filtration, the extract from leaves crushed infected tobacco plants indicates that remain infected. There is a possibility toxins produced by the bacteria is due to Ivanovski recommended infection, but does not deal with it. Was thought to be that it can be retained by the filter is an infectious agent, all grown in nutrient medium at the time – this was a part of the germ theory of disease. 1898, solution to repeat the experiment, was filtered, was convinced that a new form of infectious agent is included microbiologist Martinus bay error link in the Netherlands. He multiplied only in cells that have been split the agent, but his efforts did not indicate that it was made of particles, Kontagiumu vivum fluidum it (soluble living germ), he was re-introduced It is pointed out that it is called the word virus. The virus later in nature, they insisted it was a credit theory liquid by a certification Wendell Stanley was particulate Beijerinck. Paul Frosch and Friedrich Loeffler has passed the first animal virus in the same year – agent of foot (Aphthovirus) in the mouth – through a filter similar.
In the early 20th century, to discover a group of viruses that infect bacteria, called (general or phage) bacteriophage, microbiologist Felix d’Herelle French-Canadian, microbiologist Frederick port Wort in the UK that, added to the bacteria now Description agar the virus, it will generate a region of dead bacteria. Dilute suspension of such viruses exactly, (the lowest concentration of virus) was found the highest dilution, but it does not kill all bacteria from different regions of the organism dead it. It counts these regions, multiplying the dilution factor he could calculate the number of viruses in the suspension of the original. Phage, was welcomed as a potential treatment for diseases such as cholera and typhoid fever, but the promise was forgotten in the development of penicillin. The inspection of the phage, and provided insight into the switching a useful mechanism for introducing foreign genes into bacteria and gene.
The end of the 19th century, the virus was determined from the point of view of those infectious filtering, of their requirements for life and a source of power. Virus was grown in plants and animals. 1906, invented a method for growing tissue in lymph, 1928 guinea pig cornea tissue.In, RA Lambert 1913 E. Steinhardt, C., Israel fragments of MC mate and HB-mate Ross Granville Harrison In order to grow the vaccine virus, which was an increase of vaccinia virus in suspension of kidney of minced chicken using this method. The polio virus, their method was not widely adopted until the 1950s when it is grown on a large scale for the production of vaccine. Another breakthrough came in 1931 when a virus or some other influenza grew up in egg chicken pathologist Ernest William Guddopasu of America. 1949, Frederick Robbins John Franklin Enders, and Thomas Weller,, polio virus in cultured cells increased from human embryos, the first virus is grown without the use of eggs and solid animal tissues. This work, was able to make the polio vaccine effective Jonas Salk.