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Concomitant Immunity
Concomitant immunity is the phenomenon where an individual with a persistent infection displays immunity to re-infections caused by similar pathogens. In other words, the persistence of the primary infection prevents the occurrence of secondary infections. The presence of concomitant immunity depends on the nature of the immune response caused by a latent infection and hence differs from pathogen to pathogen. The concept was originally developed in tumor immunology, where a mouse with a tumor graft does not allow a second tumor graft of the same type to develop. It has also been called premunition, nonsterilizing immunity, and infection-immunity. Being dependent on an existing infection, it is a type of acquired immunity The adaptive immune system (AIS), also known as the acquired immune system, or specific immune system is a subsystem of the immune system that is composed of specialized cells, organs, and processes that eliminate pathogens specifically. The ac .... Referenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Persistent Infection
infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable disease, is an illness resulting from an infection. Infections can be caused by a wide range of pathogens, most prominently bacteria and viruses. Hosts can fight infections using their immune systems. Mammalian hosts react to infections with an innate response, often involving inflammation, followed by an adaptive response. Treatment for infections depends on the type of pathogen involved. Common medications include: * Antibiotics for bacterial infections. * Antivirals for viral infections. * Antifungals for fungal infections. * Antiprotozoals for protozoan infections. * Antihelminthics for infections caused by parasitic worms. Infectious diseases remain a significant global health concern, causing approximately 9.2 million deaths in 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acquired Immunity
The adaptive immune system (AIS), also known as the acquired immune system, or specific immune system is a subsystem of the immune system that is composed of specialized cells, organs, and processes that eliminate pathogens specifically. The acquired immune system is one of the two main immunity strategies found in vertebrates (the other being the innate immune system). Like the innate system, the adaptive immune system includes both humoral immunity components and cell-mediated immunity components and destroys invading pathogens. Unlike the innate immune system, which is pre-programmed to react to common broad categories of pathogen, the adaptive immune system is highly specific to each particular pathogen the body has encountered. Adaptive immunity creates immunological memory after an initial response to a specific pathogen, and leads to an enhanced response to future encounters with that pathogen. Antibodies are a critical part of the adaptive immune system. Adaptive imm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lymphocytic Choriomeningitis Virus
A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include T cells (for cell-mediated and cytotoxic adaptive immunity), B cells (for humoral, antibody-driven adaptive immunity), and innate lymphoid cells (ILCs; "innate T cell-like" cells involved in mucosal immunity and homeostasis), of which natural killer cells are an important subtype (which functions in cell-mediated, cytotoxic innate immunity). They are the main type of cell found in lymph, which prompted the name "lymphocyte" (with ''cyte'' meaning cell). Lymphocytes make up between 18% and 42% of circulating white blood cells. Types The three major types of lymphocyte are T cells, B cells and natural killer (NK) cells. They can also be classified as small lymphocytes and large lymphocytes based on their size and appearance. Lymphocytes can be identified by their large nucleus. T cells and B cells T cells (thymus cells) and B cells ( bone marrow- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leishmania Major
''Leishmania major'' is a species of parasite found in the genus ''Leishmania'', and is associated with the disease zoonotic cutaneous leishmaniasis (also known as Aleppo boil, Baghdad boil, Bay sore, Biskra button, Chiclero ulcer, Delhi boil, Kandahar sore, Lahore sore, Oriental sore, Pian bois, and Uta). ''L. major'' is an intracellular pathogen which infects the macrophages and dendritic cells of the immune system. Though ''Leishmania'' species are found on every continent aside from Antarctica, ''Leishmania major'' is found only in the Eastern Hemisphere, specifically in Northern Africa, the Middle East, Northwestern China, and Northwestern India. Biology Life cycle As a trypanosomatid, ''L. major'' begins its lifecycle in amastigote form in the midgut of the main vector, female sand flies ('' Phlebotomus'' ). Once in the gut of the sand fly, the parasites change from aflagelated amastigotes into flagellated promastigotes for one to two weeks until they are fully d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
T Helper Cell
The T helper cells (Th cells), also known as CD4+ cells or CD4-positive cells, are a type of T cell that play an important role in the adaptive immune system. They aid the activity of other immune cells by releasing cytokines. They are considered essential in B cell Immunoglobulin class switching, antibody class switching, breaking Cross-presentation, cross-tolerance in dendritic cells, in the activation and growth of cytotoxic T cells, and in maximizing bactericidal activity of phagocytes such as macrophages and neutrophils. CD4+ cells are mature Th cells that express the surface protein CD4. Genetic variation in regulatory elements expressed by CD4+ cells determines susceptibility to a broad class of autoimmune diseases. Structure and function Th cells contain and release cytokines to aid other immune cells. Cytokines are small protein mediators that alter the behavior of target cells that express Receptor (biochemistry), receptors for those cytokines. These cells help polar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onchocerca Volvulus
''Onchocerca volvulus'' is a filarial (arthropod-borne) nematode (roundworm) that causes onchocerciasis (river blindness), and is the second-leading cause of blindness due to infection worldwide after trachoma. It is one of the 20 neglected tropical diseases listed by the World Health Organization, with elimination from certain countries expected by 2025. John O'Neill, an Irish surgeon, first described ''Onchocerca volvulus'' in 1874, when he found it to be the causative agent of 'craw-craw', a skin disease found in West Africa. A Guatemalan doctor, Rodolfo Robles, first linked it to visual impairment in 1917. ''Onchocerca volvulus'' is primarily found in sub-Saharan Africa, and there is also disease transmission in some South American nations, as well as Yemen (see global map bottom right). It is spread from person to person via female biting blackflies of the genus ''Simulium'', and humans are the only known definitive host. Morphology ''Onchocerca volvulus'' parasites ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schistosoma
''Schistosoma'' is a genus of trematodes, commonly known as blood flukes. They are Parasitism, parasitic flatworms responsible for a highly significant group of infections in humans termed ''schistosomiasis'', which is considered by the World Health Organization to be the second-most socioeconomically devastating parasitic disease (after malaria), infecting millions worldwide. Adult flatworms parasitize blood capillaries of either the mesenteries or plexus of the bladder, depending on the infecting species. They are unique among trematodes and any other flatworms in that they are Dioecy, dioecious with distinct sexual dimorphism between male and female. Thousands of eggs are released and reach either the bladder or the intestine (according to the infecting species), and these are then excreted in urine or feces to fresh water. Larvae must then pass through an intermediate snail Host (biology), host before the next larval stage of the parasite emerges that can infect a new mammal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mycobacterium Tuberculosis
''Mycobacterium tuberculosis'' (M. tb), also known as Koch's bacillus, is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, ''M. tuberculosis'' has an unusual, waxy coating on its cell surface primarily due to the presence of mycolic acid. This coating makes the cells impervious to Gram staining, and as a result, ''M. tuberculosis'' can appear weakly Gram-positive. Acid-fastness, Acid-fast stains such as Ziehl–Neelsen stain, Ziehl–Neelsen, or Fluorescence, fluorescent stains such as Auramine O, auramine are used instead to identify ''M. tuberculosis'' with a microscope. The physiology of ''M. tuberculosis'' is highly aerobic organism, aerobic and requires high levels of oxygen. Primarily a pathogen of the mammalian respiratory system, it infects the lungs. The most frequently used diagnostic methods for tuberculosis are the Mantoux test, tuberculin skin test, Acid-Fast Stain, aci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory T Cell
Memory T cells are a subset of T lymphocytes that might have some of the same functions as memory B cells. Their lineage is unclear. Function Antigen-specific memory T cells specific to viruses or other microbial molecules can be found in both central memory T cells (TCM) and effector memory T cells (TEM) subsets. Although most information is currently based on observations in the cytotoxic T cells (CD8-positive) subset, similar populations appear to exist for both the helper T cells (CD4-positive) and the cytotoxic T cells. Primary function of memory cells is augmented immune response after reactivation of those cells by reintroduction of relevant pathogen into the body. It is important to note that this field is intensively studied and some information may not be available as of yet. * Central memory T cells (TCM): TCM lymphocytes have several attributes in common with stem cells, the most important being the ability of self-renewal, mainly because of high level of phosphoryla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
