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A serotype or serovar is a distinct variation within a
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...
of
bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a Bacte ...
or
virus A virus is a submicroscopic infectious agent that Viral replication, replicates only inside the living Cell (biology), cells of an organism. Viruses infect all types of life forms, from animals and plants to microorganisms, including bacte ...
or among immune cells of different individuals. These
microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties ...
s,
virus A virus is a submicroscopic infectious agent that Viral replication, replicates only inside the living Cell (biology), cells of an organism. Viruses infect all types of life forms, from animals and plants to microorganisms, including bacte ...
es, or
cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Closed spaces * Monastic cell, a small room, hut, or cave in which a monk or religious recluse lives * Prison cell, a room used to hold peopl ...
s are classified together based on their cell surface
antigen In immunology, an antigen (Ag) is a molecule or molecular structure, such as may be present on the outside of a pathogen, that can be bound by an antigen-specific antibody or B-cell antigen receptor. The presence of antigens in the body norma ...
s, allowing the epidemiologic classification of organisms to the subspecies level. A group of serovars with common antigens is called a serogroup or sometimes ''serocomplex''. Serotyping often plays an essential role in determining species and subspecies. The ''
Salmonella ''Salmonella'' is a genus of bacillus (shape), rod-shaped (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' is the type sp ...
''
genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer to a specific classification s ...
of
bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a Bacte ...
, for example, has been determined to have over 2600 serotypes. ''
Vibrio cholerae ''Vibrio cholerae'' is a species of Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram stain, gram-staining method of bacterial differentiation. They are characterized by their cell enve ...

Vibrio cholerae
'', the
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...
of bacteria that causes
cholera Cholera is an infection of the small intestine by some strain (biology), strains of the Bacteria, bacterium ''Vibrio cholerae''. Symptoms may range from none, to mild, to severe. The classic symptom is large amounts of watery diarrhea that lasts ...

cholera
, has over 200 serotypes, based on cell antigens. Only two of them have been observed to produce the potent
enterotoxin An enterotoxin is a protein Proteins are large biomolecules or macromolecules that are comprised of one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including E ...
that results in cholera: O1 and O139. Serotypes were discovered by the American microbiologist
Rebecca Lancefield Rebecca Craighill Lancefield (January 5, 1895 – March 3, 1981). p.227 was a prominent American microbiologist. She joined the Rockefeller Institute for Medical Research (now Rockefeller University) in New York in 1918, and was associated with t ...
in 1933.


Role in organ transplantation

The
immune system The immune system is a network of biological processes that protects an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biolog ...
is capable of discerning a cell as being 'self' or 'non-self' according to that cell's serotype. In humans, that serotype is largely determined by human leukocyte antigen (HLA), the human version of the
major histocompatibility complex The major histocompatibility complex (MHC) is a large locus on vertebrate DNA containing a set of closely linked polymorphic genes that code for cell surface proteins essential for the adaptive immune system. These cell surface proteins are ca ...
. Cells determined to be non-self are usually recognized by the immune system as foreign, causing an immune response, such as hemagglutination. Serotypes differ widely between individuals; therefore, if cells from one human (or animal) are introduced into another random human, those cells are often determined to be non-self because they do not match the self-serotype. For this reason, transplants between genetically non-identical humans often induce a problematic immune response in the recipient, leading to
transplant rejection Transplant rejection occurs when transplanted tissue is rejected by the recipient's immune system The immune system is a network of biological processes that protects an organism In biology, an organism (from Ancient Greek, Greek: ...
. In some situations this effect can be reduced by serotyping both recipient and potential donors to determine the closest HLA match.


Human leukocyte antigens


Serotyping of ''Salmonella''

The Kauffman–White classification scheme is the basis for naming the manifold serovars of ''Salmonella''. To date, more than 2600 different serotypes have been identified. A ''Salmonella'' serotype is determined by the unique combination of reactions of cell surface antigens. The "O" antigen is determined by the outermost portion of the Lipopolysaccharide (LPS) and the "H" antigen is based on the flagellar (protein) antigens. There are two species of ''Salmonella'': ''Salmonella bongori'' and ''Salmonella enterica''. ''Salmonella enterica'' can be subdivided into six subspecies. The process to identify the serovar of the bacterium consists of finding the formula of surface antigens which represent the variations of the bacteria. The traditional method for determining the antigen formula is agglutination (biology), agglutination reactions on Microscope slide, slides. The agglutination between the antigen and the antibody is made with a specific antisera, which reacts with the antigen to produce a mass. The antigen O is tested with a bacterial suspension from an agar plate, whereas the antigen H is tested with a bacterial suspension from a broth culture. The scheme classifies the serovar depending on its antigen formula obtained via the agglutination reactions. Additional serotyping methods and alternative subtyping methodologies have been reviewed by Wattiau et al.


See also

* Biovar * Morphovar


References


External links


HLA Allele and Haplotype Frequency Database
{{Surface antigens Serology Speciation Biological classification Microbiology