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Updated: Mar 15, 2026
Injections of Lipopolysaccharide into Mice to Mimic Entrance of Microbial-derived Products After Intestinal Barrier Breach
Published on: May 2, 2018
Immuno-pathophysiological responses of mouse model to experimental infection with Brucella melitensis and its
Abdinasir Yusuf Osman1, Faez Firdaus Jesse Abdullah2, Arifah Abdul Kadir3
1Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
Abstract:
Brucella melitensis is one of the major zoonotic pathogens with significant economic implications worldwide. The pathogenicity is complex and not always well understood. Lipopolysaccharide (LPS) remains the major virulent factor of B. melitensis and responsible for the mechanism by which the pathogen causes its deleterious effects. In this study, 84 mice of 6-8 weeks old of both sexes were divided equally into 3 groups; namely Brucella melitensis infected group, lipopolysaccharide (LPS) infected group and control group. The former two groups contained 36 mice each with equal gender distribution. The control group consisted of 12 mice only. Animals in B. melitensis infected group, a single inoculum of 0.4 ml containing 109 of B. melitensis were intraperitoneally challenged while animals in LPS group, a single dose of 0.4 ml containing LPS extracted from the B. melitensis were intraperitoneally inoculated. Animals in control group received intraperitoneally, a single dose of 0.4 ml phosphate buffered saline (PBS) of pH7. Animals that were infected intraperitoneally with B. melitensis demonstrated significant clinical presentation; gross and histo-pathological evidence than LPS infected group. However, both infected groups showed elevated levels of interleukins (IL-1β and IL6), antibody levels (IgM an IgG) as early as 3 days post-infection with predominance in LPS infected group. In contrast, low levels of sex related hormonal changes in which LPS infected group showed the least concentration were also detected throughout the experimental period. In conclusion, B. melitensis can be transmitted via gastrointestinal, respiratory and reproductive tract. Moreover, LPS stimulated significantly the innate and acquired immune system without significant systemic dysfunction, suggesting potentiality of the protective properties of this component as alternative vaccine for brucellosis infection.
Insights
Brucella melitensis infection causes more severe pathology than its lipopolysaccharide (LPS) in mice. However, LPS significantly boosts immune responses, indicating its potential as a brucellosis vaccine candidate.
Area of Science:
- Veterinary Microbiology
- Immunology
- Zoonotic Diseases
Background:
- Brucella melitensis is a significant zoonotic pathogen with substantial economic impact.
- Lipopolysaccharide (LPS) is a primary virulence factor in B. melitensis, driving its detrimental effects.
- Understanding B. melitensis pathogenicity is crucial for controlling brucellosis.
Purpose of the Study:
- To compare the pathogenicity of B. melitensis infection versus isolated LPS in a murine model.
- To investigate the immune response, specifically cytokine and antibody levels, following B. melitensis and LPS challenge.
- To assess hormonal changes associated with B. melitensis and LPS exposure.
Main Methods:
- 84 mice were divided into three groups: B. melitensis infected, LPS infected, and control (PBS).
- Infection involved intraperitoneal inoculation with B. melitensis (10^9 CFU) or extracted LPS.
- Clinical signs, gross and histopathological findings, interleukin (IL-1β, IL6) levels, antibody (IgM, IgG) titers, and sex hormone concentrations were monitored.
Main Results:
- B. melitensis infection induced more pronounced clinical, gross, and histopathological changes compared to LPS.
- Both infected groups exhibited elevated IL-1β, IL6, IgM, and IgG levels, with a predominance in the LPS group.
- Minimal sex-related hormonal alterations were observed, with the LPS group showing the lowest concentrations.
Conclusions:
- B. melitensis infection leads to significant pathology, while LPS primarily stimulates innate and adaptive immunity with less systemic dysfunction.
- LPS demonstrates potential as a protective component for an alternative brucellosis vaccine.
- Brucellosis transmission routes include gastrointestinal, respiratory, and reproductive tracts.
