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Properties of free endotoxin from Pasteurella multocida
Abstract:
Free endotoxin (FET) from virulent encapsulated Pasteurella multocida or from an avirulent nonencapsulated mutant is capable of inducing active immunity, but the lipopolysaccharide (LPS) moiety of the endotoxin is not. These results suggest that a protein of P multocida is involved in the stimulation of active immunity. The serologic specificity of the FET is associated with the LPS moiety, which is related to a heat extracted antigen that is used for serotyping P multocida. The FET is capable of producing widespread vascular alteration and death. It is present in the vascular system of turkeys with acute fowl cholera, and it can be detected with the "Limulus" test for endotoxins and with the gel diffusion precipitin test.
Insights
Free endotoxin from Pasteurella multocida induces immunity through a protein component, not its lipopolysaccharide. This finding is crucial for understanding fowl cholera and developing effective vaccines against this bacterial disease.
Area of Science:
- Veterinary immunology
- Bacteriology
- Molecular biology
Background:
- Pasteurella multocida causes fowl cholera, a significant disease in turkeys.
- Endotoxins are lipopolysaccharides (LPS) from Gram-negative bacteria, known for toxicity and immune stimulation.
- The specific components of P. multocida responsible for active immunity were not fully elucidated.
Purpose of the Study:
- To determine the immunogenic component of free endotoxin (FET) from Pasteurella multocida.
- To investigate the role of lipopolysaccharide (LPS) versus protein in FET-induced active immunity.
- To understand the serologic specificity and pathogenic potential of FET.
Main Methods:
- Isolation and characterization of free endotoxin (FET) from virulent and avirulent P. multocida strains.
- Assessment of active immunity induction by FET and its components.
- Serologic analysis using heat-extracted antigens.
- Detection of FET in infected turkeys using the Limulus test and gel diffusion precipitin test.
Main Results:
- Free endotoxin (FET) induced active immunity, but the lipopolysaccharide (LPS) moiety alone did not.
- A protein component of FET was implicated in stimulating active immunity.
- Serologic specificity was linked to the LPS moiety, correlating with heat-extracted antigens used for serotyping.
- FET caused vascular alterations and death, and was detected in turkeys with acute fowl cholera.
Conclusions:
- A protein component of Pasteurella multocida endotoxin is responsible for inducing active immunity.
- The LPS moiety of FET provides serologic specificity but is not the primary immunogen for active immunity.
- FET plays a role in the pathogenesis of acute fowl cholera and can be detected using specific diagnostic tests.