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Plasmid-mediated adhesion in enteropathogenic Escherichia coli
Abstract:
A survey of classical serotype enteropathogenic Escherichia coli has been made with respect to their plasmid profile and ability to adhere to HEp-2 cells. Thirty-one of the 32 strains examined contained a 50-70 Md plasmid, and many exhibited HEp-2 adherence. Strain E2348 (0127:H6), which causes diarrhea in volunteers and is HEp-2-adhesive, was chosen for further study. The large 55 Md plasmid in E2348, pMAR2, has been marked with a transposon coding for ampicillin resistance. E2348 that has been cured of pMAR2 loses the ability to adhere to HEp-2 cells, while HB101, a nonadherent E. coli K12, acquires HEp-2 adhesiveness after gaining this plasmid. Plasmid presence was also shown to correlate with in vivo adhesion to intestine, using the colostrum-deprived piglet model.
Insights
Enteropathogenic Escherichia coli adhesion to host cells is often mediated by a specific plasmid. This 55 Md plasmid, pMAR2, confers HEp-2 cell adherence and intestinal adhesion in vivo.
Area of Science:
- Microbiology
- Molecular Biology
- Infectious Diseases
Background:
- Enteropathogenic Escherichia coli (EPEC) are a significant cause of diarrheal disease.
- Plasmid profiles and adherence capabilities are key characteristics of pathogenic bacteria.
- HEp-2 cell adherence is a common in vitro model for studying bacterial pathogenicity.
Purpose of the Study:
- To investigate the role of plasmids in the adherence of classical serotype enteropathogenic Escherichia coli to HEp-2 cells.
- To identify specific plasmids associated with HEp-2 cell adherence and in vivo intestinal adhesion.
Main Methods:
- Survey of plasmid profiles in 32 enteropathogenic Escherichia coli strains.
- Assessment of HEp-2 cell adherence for each strain.
- Genetic manipulation of a specific 55 Md plasmid (pMAR2) in strain E2348, including transposon marking for ampicillin resistance.
- Plasmid curing experiments to assess the effect on HEp-2 adherence.
- Plasmid transfer experiments to a non-adherent E. coli K12 strain (HB101).
- In vivo adhesion studies using a colostrum-deprived piglet model.
Main Results:
- Thirty-one of 32 EPEC strains harbored a 50-70 Md plasmid, with many showing HEp-2 adherence.
- Strain E2348 (O127:H6), a diarrhea-causing EPEC, possesses a 55 Md plasmid (pMAR2) crucial for HEp-2 adherence.
- Curing E2348 of pMAR2 abolished HEp-2 adherence; HB101 gained HEp-2 adhesiveness upon receiving this plasmid.
- Plasmid presence correlated with in vivo intestinal adhesion in piglets.
Conclusions:
- A specific 55 Md plasmid (pMAR2) is essential for the HEp-2 cell adherence of enteropathogenic Escherichia coli strain E2348.
- This plasmid confers both in vitro (HEp-2 cells) and in vivo (intestinal) adhesive properties.
- Plasmid-mediated adherence is a critical factor in the pathogenicity of enteropathogenic Escherichia coli.