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Implementation of a Permeable Membrane Insert-based Infection System to Study the Effects of Secreted Bacterial Toxins on Mammalian Host Cells
Published on: August 19, 2016
Toxin production by Pasteurella granulomatis
H P Veit1, D J Wise, G R Carter
1Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg 24061-0442, USA.
Annals of the New York Academy of Sciences
|July 21, 1998
Summary
Pasteurella granulomatis, a bacterium causing lechiguana in cattle, exhibits variable hemolytic and leukotoxic activities. These properties may influence the severity of the disease in affected animals.
Area of Science:
- Veterinary Microbiology
- Bacterial Pathogenesis
Background:
- Pasteurella granulomatis (Pg) is a newly identified bacterium linked to proliferative fibrogranulomatous panniculitis (lechiguana) in Brazilian cattle.
- Previous attempts to replicate lechiguana experimentally have yielded limited success, suggesting other virulence factors may be involved.
Purpose of the Study:
- To investigate the hemolytic and leukotoxic potential of selected Pasteurella granulomatis isolates.
- To assess the contribution of these toxins to the pathogenicity of Pg in cattle.
Main Methods:
- Seven Pg isolates were tested for hemolytic activity on ovine and bovine blood agar plates.
- The CAMP test was employed to confirm hemolytic activity on bovine blood agar.
- Leukotoxicity was evaluated using MTT dye reduction assays and Alamar blue tests with bovine neutrophils.
Main Results:
- Two of seven Pg isolates showed hemolysis on bovine blood agar; all seven were hemolytic on ovine blood agar.
- All seven isolates demonstrated enhanced hemolysis on bovine blood agar via the CAMP reaction.
- Preliminary assays indicated leukotoxicity in 13 of 16 Pg cultures (MTT assay), with all seven isolates showing leukotoxic activity (Alamar blue test).
Conclusions:
- Pasteurella granulomatis isolates display variable hemolytic and leukotoxic properties.
- The presence and degree of these hemolytic and leukotoxic activities may correlate with the pathogenicity of Pg in susceptible cattle.
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