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Original Antigenic Sin
Original antigenic sin, also known as antigenic imprinting, the Hoskins effect, or immunological imprinting, is the propensity of the immune system to preferentially use immunological memory based on a previous infection when a second slightly different version of that foreign pathogen (e.g. a virus or bacterium) is encountered. This leaves the immune system "trapped" by the first response it has made to each antigen, and unable to mount potentially more effective responses during subsequent infections. Antibodies or T-cells induced during infections with the first variant of the pathogen are subject to repertoire freeze, a form of original antigenic sin. The phenomenon has been described in relation to influenza virus, SARS-CoV-2, dengue fever, human immunodeficiency virus (HIV) and to several other viruses. History This phenomenon was first described in 1960 by Thomas Francis Jr. in the article "On the Doctrine of Original Antigenic Sin". It is named by analogy to the Chri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Original Antigenic Sin
Original antigenic sin, also known as antigenic imprinting, the Hoskins effect, or immunological imprinting, is the propensity of the immune system to preferentially use immunological memory based on a previous infection when a second slightly different version of that foreign pathogen (e.g. a virus or bacterium) is encountered. This leaves the immune system "trapped" by the first response it has made to each antigen, and unable to mount potentially more effective responses during subsequent infections. Antibodies or T-cells induced during infections with the first variant of the pathogen are subject to repertoire freeze, a form of original antigenic sin. The phenomenon has been described in relation to influenza virus, SARS-CoV-2, dengue fever, human immunodeficiency virus (HIV) and to several other viruses. History This phenomenon was first described in 1960 by Thomas Francis Jr. in the article "On the Doctrine of Original Antigenic Sin". It is named by analogy to the Chri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epitopes
An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The epitope is the specific piece of the antigen to which an antibody binds. The part of an antibody that binds to the epitope is called a paratope. Although epitopes are usually non-self proteins, sequences derived from the host that can be recognized (as in the case of autoimmune diseases) are also epitopes. The epitopes of protein antigens are divided into two categories, conformational epitopes and linear epitopes, based on their structure and interaction with the paratope. Conformational and linear epitopes interact with the paratope based on the 3-D conformation adopted by the epitope, which is determined by the surface features of the involved epitope residues and the shape or tertiary structure of other segments of the antigen. A conformational epitope is formed by the 3-D conformation adopted by the inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vaccine
A vaccine is a biological preparation that provides active acquired immunity to a particular infectious or malignant disease. The safety and effectiveness of vaccines has been widely studied and verified. A vaccine typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins. The agent stimulates the body's to recognize the agent as a threat, destroy it, and to further recognize and destroy any of the microorganisms associated with that agent that it may encounter in the future. Vaccines can be prophylactic (to prevent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dengue Hemorrhagic Fever
Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic skin itching and skin rash. Recovery generally takes two to seven days. In a small proportion of cases, the disease develops into a more severe dengue hemorrhagic fever, resulting in bleeding, low levels of blood platelets and blood plasma leakage, or into dengue shock syndrome, where dangerously low blood pressure occurs. Dengue is spread by several species of female mosquitoes of the ''Aedes'' genus, principally ''Aedes aegypti''. The virus has five serotypes; infection with one type usually gives lifelong immunity to that type, but only short-term immunity to the others. Subsequent infection with a different type increases the risk of severe complications. A number of tests are available to confirm the diagnosis including detecting a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endothelium
The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel wall. Endothelial cells form the barrier between vessels and tissue and control the flow of substances and fluid into and out of a tissue. Endothelial cells in direct contact with blood are called vascular endothelial cells whereas those in direct contact with lymph are known as lymphatic endothelial cells. Vascular endothelial cells line the entire circulatory system, from the heart to the smallest capillaries. These cells have unique functions that include fluid filtration, such as in the glomerulus of the kidney, blood vessel tone, hemostasis, neutrophil recruitment, and hormone trafficking. Endothelium of the interior surfaces of the heart chambers is called endocardium. An impaired function can lead to serious health issues thr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vascular Permeability
Vascular permeability, often in the form of capillary permeability or microvascular permeability, characterizes the capacity of a blood vessel wall to allow for the flow of small molecules (drugs, nutrients, water, ions) or even whole cells (lymphocytes on their way to the site of inflammation) in and out of the vessel. Blood vessel walls are lined by a single layer of endothelial cells. The gaps between endothelial cells ( cell junctions) are strictly regulated depending on the type and physiological state of the tissue. There are several techniques to measure vascular permeability to certain molecules. For instance, the cannulation of a single microvessel with a micropipette, the microvessel is perfused with a certain pressure, occluded downstream and then the velocity of some cells will be related to the permeability.Michel, C. C., Mason, J. C., Curry, F. E. & Tooke, J. E. Development of Landis Technique for Measuring Filtration Coefficient of Individual Capillaries in Frog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lysis
Lysis ( ) is the breaking down of the membrane of a cell, often by viral, enzymic, or osmotic (that is, "lytic" ) mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a ''lysate''. In molecular biology, biochemistry, and cell biology laboratories, cell cultures may be subjected to lysis in the process of purifying their components, as in protein purification, DNA extraction, RNA extraction, or in purifying organelles. Many species of bacteria are subject to lysis by the enzyme lysozyme, found in animal saliva, egg white, and other secretions. Phage lytic enzymes (lysins) produced during bacteriophage infection are responsible for the ability of these viruses to lyse bacterial cells. Penicillin and related β-lactam antibiotics cause the death of bacteria through enzyme-mediated lysis that occurs after the drug causes the bacterium to form a defective cell wall. If the cell wall is completely lost and the penicillin was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytokines
Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrine signaling, autocrine, paracrine signaling, paracrine and endocrine signaling as Immunomodulation, immunomodulating agents. Cytokines include chemokines, interferons, interleukins, lymphokines, and tumour necrosis factors, but generally not hormones or growth factors (despite some growth factor#cytokine, overlap in the terminology). Cytokines are produced by a broad range of cells, including immune cells like macrophages, B cell, B lymphocytes, T cell, T lymphocytes and mast cells, as well as Endothelium, endothelial cells, fibroblasts, and various stromal cells; a given cytokine may be produced by more than one type of cell. They act through cell surface receptors and are especially important in the immune system; cytokines modulate the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytotoxic T Cells
A cytotoxic T cell (also known as TC, cytotoxic T lymphocyte, CTL, T-killer cell, cytolytic T cell, CD8+ T-cell or killer T cell) is a T lymphocyte (a type of white blood cell) that kills cancer cells, cells that are infected by intracellular pathogens (such as viruses or bacteria), or cells that are damaged in other ways. Most cytotoxic T cells express T-cell receptors (TCRs) that can recognize a specific antigen. An antigen is a molecule capable of stimulating an immune response and is often produced by cancer cells, viruses, bacteria or intracellular signals. Antigens inside a cell are bound to class I MHC molecules, and brought to the surface of the cell by the class I MHC molecule, where they can be recognized by the T cell. If the TCR is specific for that antigen, it binds to the complex of the class I MHC molecule and the antigen, and the T cell destroys the cell. In order for the TCR to bind to the class I MHC molecule, the former must be accompanied by a glycoprotei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2009 Flu Pandemic Vaccine
The 2009 swine flu pandemic vaccines were influenza vaccines developed to protect against the pandemic H1N1/09 virus. These vaccines either contained inactivated (killed) influenza virus, or weakened live virus that could not cause influenza. The killed virus was injected, while the live virus was given as a nasal spray. Both these types of vaccine were produced by growing the virus in chicken eggs. Around three billion doses were produced, with delivery in November 2009. In studies, the vaccine appeared both effective and safe, providing a strong protective immune response and having a similar safety profile to the usual seasonal influenza vaccine. However, about 30% of people already had some immunity to the virus, with the vaccine conferring greatest benefit on young people, since many older people are already immune through exposure to similar viruses in the past. The vaccine also provided some cross-protection against the 1918 flu pandemic strain. Early results (pre-25 D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vaccine Development
A vaccine is a biological preparation that provides active acquired immunity to a particular infectious or malignant disease. The safety and effectiveness of vaccines has been widely studied and verified. A vaccine typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins. The agent stimulates the body's to recognize the agent as a threat, destroy it, and to further recognize and destroy any of the microorganisms associated with that agent that it may encounter in the future. Vaccines can be |
B Cells
B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted or inserted into the plasma membrane where they serve as a part of B-cell receptors. When a naïve or memory B cell is activated by an antigen, it proliferates and differentiates into an antibody-secreting effector cell, known as a plasmablast or plasma cell. Additionally, B cells present antigens (they are also classified as professional antigen-presenting cells (APCs)) and secrete cytokines. In mammals, B cells mature in the bone marrow, which is at the core of most bones. In birds, B cells mature in the bursa of Fabricius, a lymphoid organ where they were first discovered by Chang and Glick, which is why the 'B' stands for bursa and not bone marrow as commonly believed. B cells, unlike the other two classes of lymphocytes, T cells ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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