The difference between O and H Antigens

bacteria O antigen and H antigen

Introduction

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:

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.