O-antigens
Definition[edit]
The lipopolysaccharide-protein somatic antigens, usually from gram-negative bacteria and are considered sero types.
Background[edit]
Serotypes are groups within a single species of microorganisms, such as bacteria or viruses, which share distinctive surface structures.
Example[edit]
Salmonella bacteria look alike under the microscope but can be separated into many serotypes based on two structures on their surface:
- The outermost portion of the bacteria’s surface covering, called the O antigen; and
- A slender threadlike structure, called the H antigen, that is part of the flagella.
O and H antigens in Salmonella[edit]
- The O antigens are distinguished by their different chemical make-up.
- The H antigens are distinguished by the protein content of the flagella.
- Each O and H antigen has a unique code number.
- Scientists determine the serotype based on the distinct combination of O and H antigens.
E-coli[edit]
When it comes E-coli O-antigens, there are over 160 different O antigen structures produced by different E. coli strains
Significance[edit]
The O-antigens are important in the serological classification of enteric bacilli.
O-specific chains[edit]
The O-specific chains determine the specificity of the O antigens of a given serotype.
Role in immunogenicity[edit]
O antigens are the immunodominant part of the lipopolysaccharide molecule in the intact bacterial cell.
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