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Endotoxin from Fusobacterium necrophorum of bovine hepatic abscess origin
Abstract:
The endotoxic activity of Fusobacterium necrophorum bov 5 was investigated. The supernatant (S) fluid and cell wall (CW) preparation, obtained after differential centrifugation of the ruptured cell mass, were lethal for mice. The toxicity of the S fluid was stable during prolonged storage, treatment with formalin, and heating for 15 minutes at 80, 100, and 121 C, but was destroyed by alkaline hydrolysis with 0.25 N NaOH. The toxic factor was found in a high molecular weight (MW) fraction after gel filtration. The properties exhibited by the toxic S fluid resembled those of endotoxic lipopolysaccharide (LPS). Extracted and partially purified LPS (endotoxin) from F necrophorum bov 5 demonstrated a mouse median lethal dose (mouse LD50) of 16.8 mg/kg of body weight. The toxic LPS material, a high molecular weight moiety as estimated by gel filtration, was resistant to ribonuclease (RNase), deoxyribonuclease (DNase), and pronase treatment. A positive Shwartzman reaction (median skin lesion dose (SLD50) equal to 3.32 mug/kg of body weight) and biphasic fever response (minimal dose required to produce a fever index of 40 sq cm which falls on the linear portion of dose-response curve (FL40) equal to 0.41 mug/kg of body weight) further indicated the toxin was endotoxin in nature. The LPS from F necrophorum bov 5 was less toxic than Salmonella typhimurium LPS; but had considerable toxicity for experimental animals. The toxic activity of the partially purified F necrophorum bov 5 endotoxin was separated into 2 fraction regions by diethylaminoethyl (DEAE)-cellulose chromatography. The data provide evidence for the production of a potent endotoxin, possibly composed of more than one toxic component, which may be released upon cell disruption.
Insights
Fusobacterium necrophorum bov 5 produces a potent endotoxin, identified as lipopolysaccharide (LPS), which is lethal to mice. This endotoxin exhibits stability and characteristic Shwartzman reactions, indicating its significant toxic potential.
Area of Science:
- Microbiology
- Immunology
- Toxicology
Background:
- Investigating the endotoxic activity of Fusobacterium necrophorum bov 5 is crucial for understanding its pathogenicity.
- Bacterial cell components, such as lipopolysaccharide (LPS), are known potent toxins.
Purpose of the Study:
- To characterize the endotoxic activity of Fusobacterium necrophorum bov 5.
- To identify and determine the nature of the toxic substance produced by this bacterium.
Main Methods:
- Differential centrifugation to isolate supernatant (S) fluid and cell wall (CW) preparations.
- Gel filtration, alkaline hydrolysis, and chromatography (DEAE-cellulose) for toxin characterization.
- Mouse models to assess lethality (LD50), Shwartzman reaction (SLD50), and fever response (FL40).
Main Results:
- Supernatant fluid and cell wall preparations were lethal to mice.
- The toxic factor was identified as a high molecular weight lipopolysaccharide (LPS) with a mouse LD50 of 16.8 mg/kg.
- The LPS was resistant to enzymatic degradation (RNase, DNase, pronase) and induced positive Shwartzman reactions and fever responses.
Conclusions:
- Fusobacterium necrophorum bov 5 produces a potent endotoxin, likely lipopolysaccharide.
- The endotoxin exhibits properties consistent with known bacterial endotoxins.
- The findings suggest the potential for multiple toxic components within the endotoxin preparation.