Analysis of a common antigenic epitope in Bacillus cereus flagellar fraction.

The strain-specific antigenicity between Bacillus cereus decreased but the common antigenicity did not change, when the flagellar antigen was treated with pH 2. Flagellar antigen of B. cereus H.1 was separated into two fractions by gel chromatography, one with a specific antigenicity (P1 fraction), and the other with a common antigenicity (P2 fraction). It was revealed that a common antigenic epitope of the P2 fraction was detected on a 61 kDa protein by further purification using a Mono Q column. This common antigenicity of flagella was increased by treatment with sodium dodecyl sulfate (SDS) and 2-mercaptoethanol, suggesting that a common antigenic epitope exists inside the flagellar component.