Related Experiment Video
Updated: Jul 31, 2026
Injections of Lipopolysaccharide into Mice to Mimic Entrance of Microbial-derived Products After Intestinal Barrier Breach
Published on: May 2, 2018
Immunization with outer-membrane protein(s) of Bacteroides fragilis: an experimental study in mice
T Khanna1, D Panigrahi, N K Ganguly
1Department of Medical Microbiology, Postgraduate Medical Institute, Chandigarh, India.
Abstract:
A crude outer-membrane protein (OMP) preparation from a strain of Bacteroides fragilis, grown in supplemented brain-heart infusion broth, was tested for its protective effect against subcutaneous infection in mice. Immunization with six doses, each of 100, 150 or 200 μg OMP preparation, gave some protection: abscesses completely disappeared 15 to 22 days after immunization. In non-immunized animals and animals immunized with doses of 10, 20, 40 or 80 μg each, well demarcated abscesses were seen beyond day 22 post-immunization. Although crude OMP elicited good antibody response, with maximum titres on day 4 post-immunization, high titres could not be associated with healing of the abscesses.
Insights
Outer-membrane proteins (OMPs) from Bacteroides fragilis showed protective effects against subcutaneous infections in mice. Higher doses of OMPs led to abscess disappearance, though antibody response did not correlate with healing.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Bacteroides fragilis is an opportunistic pathogen.
- Outer-membrane proteins (OMPs) are key antigens for bacterial immune responses.
- Subcutaneous infections can lead to abscess formation.
Purpose of the Study:
- To evaluate the protective efficacy of crude outer-membrane protein (OMP) preparations from Bacteroides fragilis against subcutaneous infection in a mouse model.
- To investigate the correlation between antibody response and the resolution of abscesses.
Main Methods:
- Mice were immunized with varying doses (10-200 μg) of crude OMP preparation from Bacteroides fragilis.
- Subcutaneous infection was induced in mice.
- Abscess formation and resolution were monitored over time.
- Antibody titers were measured post-immunization.
Main Results:
- Immunization with higher doses (100-200 μg) of OMP preparation resulted in complete abscess disappearance within 15-22 days.
- Lower doses (10-80 μg) and non-immunized controls showed persistent, well-demarcated abscesses beyond day 22.
- A good antibody response was elicited by crude OMP, with peak titers on day 4 post-immunization.
- High antibody titers did not correlate with the healing of abscesses.
Conclusions:
- Crude outer-membrane protein preparations from Bacteroides fragilis demonstrate protective potential against subcutaneous infections in mice.
- Effective protection appears to be dose-dependent, with higher doses conferring better outcomes.
- While OMPs induce an antibody response, this response alone does not guarantee abscess resolution, suggesting other immune mechanisms may be involved.
