A serovar or serotype is a grouping of microorganisms or viruses based on their cell surface antigens. Serovars allow organisms to be classified at the sub-species level; an issue of particular importance in epidemiology.^[1] A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... Groups I: dsDNA viruses II: ssDNA viruses III: dsRNA viruses IV: (+)ssRNA viruses V: (-)ssRNA viruses VI: ssRNA-RT viruses VII: dsDNA-RT viruses A virus (Latin, poison) is a microscopic particle that can infect the cells of a biological organism. ... An antigen is a substance that stimulates an immune response, especially the production of antibodies. ...

Serovars may be established based on virulence factors, lipopolysaccharides in Gram-negative bacteria, presence of an exotoxin (pertussis toxin in Bordetella pertussis, for example), plasmids, phages, or other characteristic which differentiate two members of the same species. ^[1],[2] Virulence is either the relative pathogenicity or the relative ability to do damage to the host of an infectious agent. ... A lipopolysaccharide (LPS) is any of a class of large molecules consisting of a lipid and a polysaccharide (carbohydrate) joined by a covalent bond. ... Bacteria that are Gram-negative are not stained dark blue or violet by Gram staining, in contrast to Gram-positive bacteria. ... An exotoxin is a soluble chemical excreted by a microorganism, including bacteria, fungi, algae, and protozoa. ... According to Sigma product information Pertussis toxin is released from B. pertussis in an inactive form. ... Malcolm Farmer 10:57, 24 December 2005 (UTC) Category: ... Figure 1: Schematic drawing of a bacterium with plasmids enclosed. ... This article or section does not cite its references or sources. ...

Salmonella, for example, has 1800–2000 serovars: Salmonella enterica Serovar Typhimurium, S. enterica Serovar Typhi, and S. enterica Serovar Dublin, to name a few.^[2]
Vibrio cholerae, which causes cholera, has 139 serotypes, based on cell antigens. Only two of them produce an enterotoxin and are pathogens: 0:1 and 0:139. Species S. enterica Salmonella arizonae Salmonella enteritidis Salmonella typhi Salmonella typhimurium Salmonella is a genus of rod-shaped Gram-negative enterobacteria that causes typhoid fever, paratyphoid fever and foodborne illness. ... Binomial name Salmonella enterica Salmonella enterica is a species of Salmonella bacterium. ... Binomial name Vibrio cholerae Pacini 1854 Vibrio cholerae is a gram negative bacterium with a curved-rod shape that causes cholera in humans. ... Cholera is a water-borne disease caused by the bacterium Vibrio cholerae, which is typically ingested by drinking contaminated water, or by eating improperly cooked fish, especially shellfish. ...

Historical

Serotypes were discovered by Rebecca Lancefield in 1933.

References

1. ^ ^{a b} Baron EJ (1996). Classification. In: Barron's Medical Microbiology (Barron S et al, eds.), 4th ed., Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.
2. ^ ^{a b} Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology, 4th ed., McGraw Hill. ISBN 0-8385-8529-9.