Related topics: immune system · hiv · vaccine · protein · virus

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Researchers have succeeded in detecting anti-avian influenza virus antibody in blood serum within 20 minutes, using a portable analyzer they have developed to conduct rapid on-site bio tests. If a suitable reagent is developed, ...

Team finds effective SARS-CoV-2 neutralizing antibodies

A joint research team led by Sunney Xie, Director of Beijing Advanced Innovation Center for Genomics (ICG) at Peking University (PKU) has successfully identified multiple highly potent neutralizing antibodies against the ...

Antibodies eye mosquito-transmitted Ross River fever

Ross River fever is a mosquito-transmitted disease endemic to Australia and surrounding Pacific Islands. There is no specific treatment or vaccine for Ross River virus (RRV) infection, which causes rash, fever and debilitating ...

'Promising' virus-fighting antibody found: study

An antibody that can stop the new coronavirus infecting cells in laboratory tests has been identified by researchers in the Netherlands, in what scientists say could help the development of therapies for COVID-19.

COVID-19 puts new science to the pressure test

By its very nature, science rarely offers a quick fix. New technologies and medicines often take years to prove that they are safe and effective. Yet the surging COVID-19 pandemic is forcing scientists to condense this process ...

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Antibodies (also known as immunoglobulins, abbreviated Ig) are gamma globulin proteins that are found in blood or other bodily fluids of vertebrates, and are used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses. They are typically made of basic structural units—each with two large heavy chains and two small light chains—to form, for example, monomers with one unit, dimers with two units or pentamers with five units. Antibodies are produced by a kind of white blood cell called a plasma cell. There are several different types of antibody heavy chains, and several different kinds of antibodies, which are grouped into different isotypes based on which heavy chain they possess. Five different antibody isotypes are known in mammals, which perform different roles, and help direct the appropriate immune response for each different type of foreign object they encounter.

Although the general structure of all antibodies is very similar, a small region at the tip of the protein is extremely variable, allowing millions of antibodies with slightly different tip structures, or antigen binding sites, to exist. This region is known as the hypervariable region. Each of these variants can bind to a different target, known as an antigen. This huge diversity of antibodies allows the immune system to recognize an equally wide diversity of antigens. The unique part of the antigen recognized by an antibody is called an epitope. These epitopes bind with their antibody in a highly specific interaction, called induced fit, that allows antibodies to identify and bind only their unique antigen in the midst of the millions of different molecules that make up an organism. Recognition of an antigen by an antibody tags it for attack by other parts of the immune system. Antibodies can also neutralize targets directly by, for example, binding to a part of a pathogen that it needs to cause an infection.

The large and diverse population of antibodies is generated by random combinations of a set of gene segments that encode different antigen binding sites (or paratopes), followed by random mutations in this area of the antibody gene, which create further diversity. Antibody genes also re-organize in a process called class switching that changes the base of the heavy chain to another, creating a different isotype of the antibody that retains the antigen specific variable region. This allows a single antibody to be used by several different parts of the immune system. Production of antibodies is the main function of the humoral immune system.

This text uses material from Wikipedia, licensed under CC BY-SA