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Immune Evasion
Antigenic escape, immune escape, immune evasion or escape mutation occurs when the immune system of a host, especially of a human being, is unable to respond to an infectious agent: the host's immune system is no longer able to recognize and eliminate a pathogen, such as a virus. This process can occur in a number of different ways of both a genetic and an environmental nature. Such mechanisms include homologous recombination, and manipulation and resistance of the host's immune responses. Different antigens are able to escape through a variety of mechanisms. For example, the African trypanosome parasites are able to clear the host's antibodies, as well as resist lysis and inhibit parts of the innate immune response. A bacteria, ''Bordetella pertussis'', is able to escape the immune response by inhibiting neutrophils and macrophages from invading the infection site early on. One cause of antigenic escape is that a pathogen's epitopes (the binding sites for immune cells) become too ... [...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] |
Vaccination
Vaccination is the administration of a vaccine to help the immune system develop immunity from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating the body's adaptive immunity, they help prevent sickness from an infectious disease. When a sufficiently large percentage of a population has been vaccinated, herd immunity results. Herd immunity protects those who may be immunocompromised and cannot get a vaccine because even a weakened version would harm them. The effectiveness of vaccination has been widely studied and verified. Vaccination is the most effective method of preventing infectious diseases; widespread immunity due to vaccination is largely responsible for the worldwide eradication of smallpox and the elimination of diseases such as polio and tetanus from much of the world. However, some diseases, such as measles outbreaks in America, have seen rising cases due to relative ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasite
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has characterised parasites as "predators that eat prey in units of less than one". Parasites include single-celled protozoans such as the agents of malaria, sleeping sickness, and amoebic dysentery; animals such as hookworms, lice, mosquitoes, and vampire bats; fungi such as Armillaria mellea, honey fungus and the agents of ringworm; and plants such as mistletoe, dodder, and the Orobanchaceae, broomrapes. There are six major parasitic Behavioral ecology#Evolutionarily stable strategy, strategies of exploitation of animal hosts, namely parasitic castration, directly transmitted parasitism (by contact), wikt:trophic, trophicallytransmitted parasitism (by being eaten), Disease vector, vector-transmitted parasitism, parasitoidism, and micropreda ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trypanosomes
Trypanosomatida is a group of kinetoplastid excavates distinguished by having only a single flagellum. The name is derived from the Greek ''trypano'' (borer) and ''soma'' (body) because of the corkscrew-like motion of some trypanosomatid species. All members are exclusively parasitic, found primarily in insects. A few genera have life-cycles involving a secondary host, which may be a vertebrate, invertebrate or plant. These include several species that cause major diseases in humans. Some trypanosomatida are intracellular parasites, with the important exception of Trypanosoma brucei. Medical importance The three major human diseases caused by trypanosomatids are; African trypanosomiasis (sleeping sickness, caused by ''Trypanosoma brucei'' and transmitted by tsetse flies), South American trypanosomiasis (Chagas disease, caused by '' T. cruzi'' and transmitted by triatomine bugs), and leishmaniasis (a set of trypanosomal diseases caused by various species of ''Leishmania'' trans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunoglobulins
An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the pathogen, called an antigen. Each tip of the "Y" of an antibody contains a paratope (analogous to a lock) that is specific for one particular epitope (analogous to a key) on an antigen, allowing these two structures to bind together with precision. Using this binding mechanism, an antibody can ''tag'' a microbe or an infected cell for attack by other parts of the immune system, or can neutralize it directly (for example, by blocking a part of a virus that is essential for its invasion). To allow the immune system to recognize millions of different antigens, the antigen-binding sites at both tips of the antibody come in an equally wide variety. In contrast, the remainder of the antibody is relatively constant. It only occurs in a few varian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Protein
Membrane proteins are common proteins that are part of, or interact with, biological membranes. Membrane proteins fall into several broad categories depending on their location. Integral membrane proteins are a permanent part of a cell membrane and can either penetrate the membrane (transmembrane) or associate with one or the other side of a membrane ( integral monotopic). Peripheral membrane proteins are transiently associated with the cell membrane. Membrane proteins are common, and medically important—about a third of all human proteins are membrane proteins, and these are targets for more than half of all drugs. Nonetheless, compared to other classes of proteins, determining membrane protein structures remains a challenge in large part due to the difficulty in establishing experimental conditions that can preserve the correct conformation of the protein in isolation from its native environment. Function Membrane proteins perform a variety of functions vital to the sur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Repair
DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA damage, resulting in tens of thousands of individual molecular lesions per cell per day. Many of these lesions cause structural damage to the DNA molecule and can alter or eliminate the cell's ability to transcribe the gene that the affected DNA encodes. Other lesions induce potentially harmful mutations in the cell's genome, which affect the survival of its daughter cells after it undergoes mitosis. As a consequence, the DNA repair process is constantly active as it responds to damage in the DNA structure. When normal repair processes fail, and when cellular apoptosis does not occur, irreparable DNA damage may occur, including double-strand breaks and DNA crosslinkages (interstrand crosslinks or ICLs). This can eventually lead to malignant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Stomach
The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach is involved in the gastric phase of digestion, following chewing. It performs a chemical breakdown by means of enzymes and hydrochloric acid. In humans and many other animals, the stomach is located between the oesophagus and the small intestine. The stomach secretes digestive enzymes and gastric acid to aid in food digestion. The pyloric sphincter controls the passage of partially digested food (chyme) from the stomach into the duodenum, where peristalsis takes over to move this through the rest of intestines. Structure In the human digestive system, the stomach lies between the oesophagus and the duodenum (the first part of the small intestine). It is in the left upper quadrant of the abdominal cavity. The top of the stomach lies against ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helicobacter Pylori
''Helicobacter pylori'', previously known as ''Campylobacter pylori'', is a gram-negative, microaerophilic, spiral (helical) bacterium usually found in the stomach. Its helical shape (from which the genus name, helicobacter, derives) is thought to have evolved in order to penetrate the mucoid lining of the stomach and thereby establish infection. The bacterium was first identified in 1982 by the Australian doctors Barry Marshall and Robin Warren. ''H. pylori'' has been associated with cancer of the mucosa-associated lymphoid tissue in the stomach, esophagus, colon, rectum, or tissues around the eye (termed extranodal marginal zone B-cell lymphoma of the cited organ), and of lymphoid tissue in the stomach (termed diffuse large B-cell lymphoma). ''H. pylori'' infection usually has no symptoms but sometimes causes gastritis (stomach inflammation) or ulcers of the stomach or first part of the small intestine. The infection is also associated with the development of cer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The New York Times
''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid digital subscribers. It also is a producer of popular podcasts such as '' The Daily''. Founded in 1851 by Henry Jarvis Raymond and George Jones, it was initially published by Raymond, Jones & Company. The ''Times'' has won 132 Pulitzer Prizes, the most of any newspaper, and has long been regarded as a national " newspaper of record". For print it is ranked 18th in the world by circulation and 3rd in the U.S. The paper is owned by the New York Times Company, which is publicly traded. It has been governed by the Sulzberger family since 1896, through a dual-class share structure after its shares became publicly traded. A. G. Sulzberger, the paper's publisher and the company's chairman, is the fifth generation of the family to head the pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
E484K
There are many variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19). Some are believed, or have been stated, to be of particular importance due to their potential for increased transmissibility, increased virulence, or reduced effectiveness of vaccines against them. These variants contribute to the continuation of the COVID-19 pandemic. only the Omicron variant is designated as a circulating variant of concern by the World Health Organization. Overview The emergence of SARS-CoV-2 may have resulted from recombination events between a bat SARS-like coronavirus and a pangolin coronavirus through cross-species transmission. The earliest available SARS-CoV-2 viral genomes were collected from patients in December 2019, and Chinese researchers compared these early genomes with bat and pangolin coronavirus strains to estimate the ancestral human coronavirus type; the identified ancestral genom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variants Of SARS-CoV-2
There are many variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19). Some are believed, or have been stated, to be of particular importance due to their potential for increased transmissibility, increased virulence, or reduced effectiveness of vaccines against them. These variants contribute to the continuation of the COVID-19 pandemic. only the Omicron variant is designated as a circulating variant of concern by the World Health Organization. Overview The emergence of SARS-CoV-2 may have resulted from recombination events between a bat SARS-like coronavirus and a pangolin coronavirus through cross-species transmission. The earliest available SARS-CoV-2 viral genomes were collected from patients in December 2019, and Chinese researchers compared these early genomes with bat and pangolin coronavirus strains to estimate the ancestral human coronavirus type; the identified ancestral genome type ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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