What is the Difference Between O and H Antigen?
🆚 Go to Comparative Table 🆚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:
- Composition: O antigens are made of polysaccharides, while H antigens are composed of protein.
- 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.
- Heat Sensitivity: O antigens are heat stable, but H antigens are heat-labile.
- Alcohol Sensitivity: O antigens are resistant to alcohol, while H antigens are sensitive to alcohol.
- 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:
Characteristic | O Antigen | H Antigen |
---|---|---|
Type | Somatic Antigen | Flagellar Antigen |
Composition | Polysaccharide | Proteinaceous (Flagellin) |
Antibody Formation | Rapid and Early | Rapid and Sustained |
Level | Falls off quickly | Persists for longer periods |
Heat Sensitivity | Heat stable | Heat-labile |
Alcohol Sensitivity | Resistance to alcohol | Sensitive to alcohol |
Extraction | Trichloro-acetic acid used for extraction | Formaldehyde used for extraction |
Immunogenicity | Less immunogenic | Highly immunogenic |
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.
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