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Permissive Block Working
{{about, , the 1970 British film, Permissive (film), the grammatical mode, Permissive mood, the flavor of software license, permissive free software licence A permissive cell or host is one that allows a virus to circumvent its defenses and replicate. Usually this occurs when the virus has modulated one or several of the host cellular intrinsic defenses and the host immune system. The permissive state of a host has now been determined to be the primary factor in determining whether a virus will cause pathological symptoms in a host. Susceptible ''versus'' permissive A virus can enter a susceptible cell, but it cannot replicate. A virus can replicate in a permissive cell. Viral replication will therefore only occur in a cell that 1) facilitates entry (susceptible cell) and 2) supports intracellular replication (permissive cell). The significance between the difference of the two has now been elucidated with study of the rabbit-lethal myxoma virus. Many species of rabbit cells in ... [...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] |
Immunosuppression
Immunosuppression is a reduction of the activation or efficacy of the immune system. Some portions of the immune system itself have immunosuppressive effects on other parts of the immune system, and immunosuppression may occur as an adverse reaction to treatment of other conditions. In general, deliberately induced immunosuppression is performed to prevent the body from rejecting an organ transplant. Additionally, it is used for treating graft-versus-host disease after a bone marrow transplant, or for the treatment of auto-immune diseases such as systemic lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome, or Crohn's disease. This is typically done using medications, but may involve surgery (splenectomy), plasmapheresis, or radiation. A person who is undergoing immunosuppression, or whose immune system is weak for some other reasons (such as chemotherapy or HIV), is said to be ''immunocompromised''. Deliberately induced Administration of immunosuppressive medic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immune System
The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinters, distinguishing them from the organism's own healthy tissue. Many species have two major subsystems of the immune system. The innate immune system provides a preconfigured response to broad groups of situations and stimuli. The adaptive immune system provides a tailored response to each stimulus by learning to recognize molecules it has previously encountered. Both use molecules and cells to perform their functions. Nearly all organisms have some kind of immune system. Bacteria have a rudimentary immune system in the form of enzymes that protect against virus infections. Other basic immune mechanisms evolved in ancient plants and animals and remain in their modern descendants. These mechanisms include phagocytosis, antimicrobial pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Susceptible Individual
In epidemiology a susceptible individual (sometimes known simply as a susceptible) is a member of a population who is at risk of becoming infected by a disease. Susceptible individuals Susceptibles have been exposed to neither the wild strain of the disease nor a vaccination against it, and thus have not developed immunity. Those individuals who have antibodies against an antigen associated with a particular infectious disease will not be susceptible, even if they did not produce the antibody themselves (for example, infants younger than six months who still have maternal antibodies passed through the placenta and from the colostrum, and adults who have had a recent injection of antibodies). However, these individuals soon return to the susceptible state as the antibodies are broken down. Some individuals may have a natural resistance to a particular infectious disease. However, except in some special cases such as malaria, these individuals make up such a small proportion of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rabbit
Rabbits, also known as bunnies or bunny rabbits, are small mammals in the family Leporidae (which also contains the hares) of the order Lagomorpha (which also contains the pikas). ''Oryctolagus cuniculus'' includes the European rabbit species and its descendants, the world's 305 breeds of domestic rabbit. ''Sylvilagus'' includes 13 wild rabbit species, among them the seven types of cottontail. The European rabbit, which has been introduced on every continent except Antarctica, is familiar throughout the world as a wild prey animal and as a domesticated form of livestock and pet. With its widespread effect on ecologies and cultures, the rabbit is, in many areas of the world, a part of daily life—as food, clothing, a companion, and a source of artistic inspiration. Although once considered rodents, lagomorphs like rabbits have been discovered to have diverged separately and earlier than their rodent cousins and have a number of traits rodents lack, like two extra incis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myxoma Virus
''Myxoma virus'' is a poxvirus in the genus ''Leporipoxvirus''. The two broad geographic types of ''myxoma virus'' are Californian and South American. Californian ''myxoma virus'' is found on the West Coast of the United States, the Baja Peninsula of Mexico, and the southwest coast of Canada. South American or Brazilian ''myxoma virus'' is found in South and Central America. South American'' myxoma virus ''circulates in the jungle rabbit or tapeti (''Sylvilagus brasiliensis''), whereas Californian ''myxoma virus'' circulates in the brush rabbit (''Sylvilagus bachmani''). In their native hosts, the viruses cause the formation of benign cutaneous fibromas rather than systemic disease. Transmission ''Myxoma virus'' is passively transmitted on the mouth parts of mosquitoes, (such as '' Aedes aegyptii'') or fleas, and presumably other biting arthropods. It can also be spread through direct contact and contaminated fomites. Myxomatosis Myxomatosis is the name of the lethal dissemina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inoculation
Inoculation is the act of implanting a pathogen or other microorganism. It may refer to methods of artificially inducing immunity against various infectious diseases, or it may be used to describe the spreading of disease, as in "self-inoculation," the spreading of disease from one part of the body to another, or even to the spreading of bacteria in a Petri dish for culturing purposes. The terms "inoculation", "vaccination", and "immunization" are often used synonymously, but there are some important differences among them. Inoculation is the act of implanting a disease inside a person or animal, vaccination is the act of implanting or giving someone a vaccine specifically, and immunization is what happens to the immune system as a result. Terminology Until the early 1800s inoculation referred only to variolation (from the Latin word ''variola'' = smallpox), the predecessor to the smallpox vaccine. The smallpox vaccine, introduced by Edward Jenner in 1796, was called cowpox inoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viral Shedding
Viral shedding is the expulsion and release of virus progeny following successful reproduction during a host (biology), host cell (biology), cell infection. Once replication has been completed and the host cell is exhausted of all resources in making viral progeny, the viruses may begin to leave the cell by #Shedding from a cell into extracellular space, several methods. The term is variously used to refer to viral particles shedding from a single cell, from one part of the body into another, and from a body into the environment, where the virus may infect another. Vaccine shedding is a form of viral shedding which can occur in instances of infection caused by some attenuated vaccine, attenuated (or "live virus") vaccines. Means Shedding from a cell into extracellular space Budding (through cell envelope) Budding#Virology, "Budding" through the cell envelope—in effect, borrowing from the cell membrane to create the virus's own viral envelope— into extracellular space is mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interferon
Interferons (IFNs, ) are a group of signaling proteins made and released by host cells in response to the presence of several viruses. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses. IFNs belong to the large class of proteins known as cytokines, molecules used for communication between cells to trigger the protective defenses of the immune system that help eradicate pathogens. Interferons are named for their ability to "interfere" with viral replication by protecting cells from virus infections. However, virus-encoded genetic elements have the ability to antagonize the IFN response contributing to viral pathogenesis and viral diseases. IFNs also have various other functions: they activate immune cells, such as natural killer cells and macrophages, and they increase host defenses by up-regulating antigen presentation by virtue of increasing the expression of major histocompatibility complex (M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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