What is the Difference Between O and H Antigen?

The main differences between O and H antigens are related to their composition, location, sensitivity to heat and alcohol, and immunogenicity. Here are the key differences:

1. Composition: O antigens are made of polysaccharides, while H antigens are composed of protein.
2. Location: O antigens are part of the bacterial cell wall, specifically the lipopolysaccharide (LPS), while H antigens are found in the flagella, which are whip-like tails that bacteria use to move around.
3. Heat Sensitivity: O antigens are heat stable, but H antigens are heat-labile.
4. Alcohol Sensitivity: O antigens are resistant to alcohol, while H antigens are sensitive to alcohol.
5. Immunogenicity: O antigens induce antibody formation with low titres, while H antigens induce antibody formation with high titres.

Both O and H antigens are used together to determine serotypes of bacteria, such as Salmonella. By identifying the unique combination of O and H antigens, scientists can classify different bacterial serotypes and better understand their virulence, host range, and geographical distribution.

Comparative Table: O vs H Antigen

O antigen and H antigen are two types of antigens used to determine the different serotypes of bacteria, such as Salmonella. Here is a table comparing the differences between O and H antigens:

O antigens are part of the cell wall lipopolysaccharide (LPS) and are composed of polysaccharides, making them heat stable and alcohol resistant. On the other hand, H antigens are based on flagellar proteins and are proteinaceous, making them heat-labile and alcohol sensitive.