Antigenic variation of Campylobacter flagella

Area of Science:

• Microbiology
• Immunology
• Bacterial Genetics

Background:

• Campylobacter species are significant human pathogens.
• Flagella play a crucial role in bacterial motility and host-pathogen interactions.
• Antigenic variation in bacterial surface structures is a key immune evasion strategy.

Purpose of the Study:

• To investigate the flagellar heterogeneity in Campylobacter coli and Campylobacter jejuni serogroup LIO 8.
• To characterize the flagellin subunits and their antigenic specificities.
• To elucidate the mechanism and rate of antigenic variation in Campylobacter.

Main Methods:

• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to analyze flagellin molecular weights.
• Immunoelectron microscopy to visualize flagellar filaments and their antigenic properties.
• Western blotting (immunoblotting) and immunoprecipitation to identify flagellin-antibody interactions.
• Rate determination of phase 1-to-phase 2 and phase 2-to-phase 1 transitions.

Main Results:

• Two flagellin subunits with different molecular weights (59,500 and 61,500 Da) were identified in Campylobacter strains of serogroup LIO 8.
• Two flagellum filaments with distinct antigenic specificities were observed.
• Flagella composed of Mr 61,500 flagellin did not carry the serological determinants for LIO 8 serogroup.
• Bidirectional antigenic variation between the two flagellum types was demonstrated in Campylobacter coli VC167.
• Phase 1-to-phase 2 transition rate was approximately 2.0 x 10(-5) per cell per generation.
• Phase 2-to-phase 1 transition rate was approximately 1.2 x 10(-6) per cell per generation.

Conclusions:

• Campylobacter strains can exhibit flagellar antigenic variation through the production of distinct flagellin subunits.
• This variation contributes to the serological diversity within Campylobacter serogroups.
• The observed rates suggest a significant capacity for immune evasion in Campylobacter infections.