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A novel cryohemagglutinin associated with adherence of enteroaggregative Escherichia coli
T Yamamoto1, N Wakisaka, T Nakae
1Department of Infectious Diseases and Tropical Medicine, International Medical Center of Japan, Shinjuku-ku, Tokyo.
Abstract:
Strain O42 (serotype O44:H18) of enteroaggregative Escherichia coli (EAggEC) has been shown to be pathogenic in volunteer experiments. This strain exhibited plasmid (pO42)-encoded D-mannose-resistant hemagglutinating activity (MRHA) that was detected only at low temperatures (e.g., 0 degrees C) and only with human erythrocytes. The production of this cryogenic MRHA (cryo-MRHA) was observed when the bacteria were grown in liquid media and was strictly regulated by bacterial growth temperatures. Transposon-insertion mutagenesis revealed that this MRHA is associated with (i) bacterial clump formation in liquid cultures, (ii) bacterial adherence to HEp-2 cells as well as (Formalin-fixed) human colonic mucosa, and (iii) production of a 16-kDa outer membrane protein. The PCR designed on the basis of the determined cryo-MRHA-associated DNA sequence sharply distinguished strain O42 from eight other EAggEC strains whose MRHAs were detected at both cold and room temperatures to the same (or similar) extent. Strain O42 possessed a surface layer that may enhance the pO42-mediated adherence. The data suggest that a plasmid-encoded cryo-MRHA is a candidate for a major adhesin of EAggEC strain O42.
Insights
Enteroaggregative Escherichia coli (EAggEC) strain O42 exhibits a unique cold-regulated D-mannose-resistant hemagglutinating activity (cryo-MRHA). This cryo-MRHA is linked to bacterial adherence and may function as a key adhesin in EAggEC O42 pathogenesis.
Area of Science:
- Microbiology
- Pathogen Adherence Mechanisms
- Bacterial Genetics
Background:
- Enteroaggregative Escherichia coli (EAggEC) is a significant human enteric pathogen.
- Strain O42 (serotype O44:H18) is a known pathogenic EAggEC strain.
- Plasmid-encoded factors contribute to E. coli virulence.
Purpose of the Study:
- To investigate the D-mannose-resistant hemagglutinating activity (MRHA) of EAggEC strain O42.
- To identify the genetic basis and functional role of cryo-MRHA in EAggEC O42.
- To differentiate strain O42 from other EAggEC strains based on MRHA characteristics.
Main Methods:
- Cryogenic MRHA (cryo-MRHA) detection at low temperatures (0°C) using human erythrocytes.
- Transposon-insertion mutagenesis to identify associated genes.
- Polymerase Chain Reaction (PCR) to analyze cryo-MRHA-associated DNA sequences.
- Assessment of bacterial adherence to HEp-2 cells and human colonic mucosa.
Main Results:
- EAggEC strain O42 produces a unique cryo-MRHA regulated by bacterial growth temperature.
- Cryo-MRHA is associated with bacterial clumping, adherence to host cells, and a 16-kDa outer membrane protein.
- A specific DNA sequence linked to cryo-MRHA distinguished strain O42 from other EAggEC strains.
- Strain O42 possesses a surface layer potentially enhancing adherence.
Conclusions:
- Plasmid-encoded cryo-MRHA is a potential major adhesin for EAggEC strain O42.
- Cryo-MRHA plays a role in bacterial adherence and pathogenesis.
- The unique cryo-MRHA mechanism offers a potential target for diagnostic or therapeutic strategies.