Difference between O Antigen and H Antigen

The antigen used to define serological test of Salmonella include Somatic O antigen, Flagellar H antigen and Vi antigen (Capsular antigen).

Some of the differences between O Antigen and H Antigen are as follows:
Download PDF Notes

S.N.

Characteristics

O Antigen

H Antigen

1. Types Somatic Antigen Flagellar antigen
2. Composition Polysaccharide Proteinaceous
3. Antibody formation Rapid and Early Rapid and Sustained
4. Level Falls off quickly Persists for longer periods
5. Production Produces granular clumps. Produces cottony, fluffy precipitates.
6. Observation Round bottom Felix tube are used to see agglutination. Conical bottom Dreyer’s tube are used to see agglutination.
7. Heat sensitivity Somatic antigens are heat stable. Flagellar antigens are heat-labile.
8. Alcohol sensitivity Resistance to alcohol Sensitive to alcohol
9. Extraction Trichloro-acetic acid is used for extraction of O antigens. Formaldehyde is used for extraction of H antigens.
10. Immunogenicity Less immunogenic Highly immunogenic
11. Antibody formation Produces antibody formation with low titres. Induces antibody formation with high titres.

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