The difference between O and H Antigens

bacteria cell with O antigen and H antigen
bacteria O antigen and H antigen


Bacteria are organisms living a single cell life. they are prokaryotes and are of significant in food web and food chain system. Lets discuss about these two antigens (H antigen and O antigen) from the bacteria. O antigens are major components of the surface lipopolysaccharide (LPS) of bacteria while H antigens are slender threadlike part of the flagella of bacteria. So, this is the key difference between O and H antigen. Besides, the O antigen is a polysaccharide while H antigen is a protein.

summarized differences between O Antigen and H Antigen are as follows:



O Antigen

H Antigen

1.TypesSomatic AntigenFlagellar antigen
3.Antibody formationRapid and EarlyRapid and Sustained
4.LevelFalls off quicklyPersists for longer periods
5.ProductionProduces granular clumps.Produces cottony, fluffy precipitates.
6.ObservationRound bottom Felix tube are used to see agglutination.Conical bottom Dreyer’s tube are used to see agglutination.
7.Heat sensitivitySomatic antigens are heat stable.Flagellar antigens are heat-labile.
8.Alcohol sensitivityResistance to alcoholSensitive to alcohol
9.ExtractionTrichloro-acetic acid is used for extraction of O antigens.Formaldehyde is used for extraction of H antigens.
10.ImmunogenicityLess immunogenicHighly immunogenic
11.Antibody formationProduces antibody formation with low titres.Induces antibody formation with high titres.