What is O antigen used for?

The O-antigen, which is one of the most variable constituents on the cell surface, has been used widely and traditionally for serological classification of many gram-negative bacteria.

What is K antigen capsule?

The capsular or K-antigen is composed of high molecular weight polysaccharide and forms a dense, high molecular weight coat outside of the bacterial cells. Encapsulated pathogens can become invasive and cause septicemia due to their increased resistance to phagocytosis and complement-mediated killing.

Where is O antigen found?

The O antigen, consisting of many repeats of an oligosaccharide unit, is part of the lipopolysaccharide (LPS) in the outer membrane of Gram-negative bacteria.

Why capsular antigen is called K antigen?

LPS contains O-linked polysaccharides (O-PS) comprised of repeating oligosaccharide units. The O-PS repeating units can be referred to as the O-antigens due to their immunogenicity. Some bacteria produce capsular polysaccharides (CPS), which are referred to as the K-antigens to distinguish them from the O-antigens.

How many O antigens are there?

Of the 187 formally defined O antigens, six (O31, O47, O67, O72, O94 and O122) have since been removed and three (O34, O89 and O144) strains do not produce any O antigen.

What is O antigen made of?

The O-antigen or O-side chain is attached to the core polysaccharide and extends from the core out into the environment. It consists of repeating oligosaccharide subunits made up of three to five sugars. The individual chains can vary in length ranging up to 40 repeat units.

What is H antigen and O antigen?

O antigen and H antigen are two types of antigens used to determine the different serotypes of bacterial species. O antigen is a lipopolysaccharide found on the cell wall. H antigen is a proteinaceous antigen which is a part of the flagella.

Is O antigen A capsule?

Such capsules are known as O-antigen (O-Ag) capsules, due to their high degree of similarity to the O-Ag of the lipopolysaccharide (LPSO-Ag). Capsular polysaccharides are known virulence factors of many bacterial pathogens, facilitating evasion of immune recognition and systemic dissemination within the host.

Is there an O antigen in blood?

blood group O – has no antigens, but both anti-A and anti-B antibodies in the plasma. blood group AB – has both A and B antigens, but no antibodies.

What antigens does O blood have?

blood group O – has no antigens, but both anti-A and anti-B antibodies in the plasma.

How can you tell the difference between O and H antigens?

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.