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Differentiation of Treponema hyodysenteriae from T innocens by enteropathogenicity testing in the CF1 mouse
Abstract:
Fourteen isolates of Treponema hyodysenteriae and 11 isolates of T innocens from eight different countries were evaluated in the CF1 strain female mouse for virulence. Mice were fasted for 24 hours and inoculated intragastrically with 1 ml of culture for two consecutive days. Mice were killed and necropsied at 12 to 15 days after inoculation. Caecitis was detected in mice from each of the groups receiving T hyodysenteriae (67 per cent) but not in mice receiving T innocens or sterile broth. Lesions consisted of hyperaemia, mucosal oedema, catarrhal inflammation and occasional haemorrhage. These studies suggest that the CF1 mouse may be an inexpensive in vivo means of differentiating T hyodysenteriae from T innocens.
Insights
The CF1 mouse model effectively differentiates virulent Treponema hyodysenteriae from non-virulent T. innocens. This study shows the CF1 mouse is a cost-effective in vivo method for distinguishing these Treponema species.
Area of Science:
- Veterinary Microbiology
- Infectious Diseases
- Animal Models
Background:
- Treponema hyodysenteriae causes swine dysentery, a significant enteric disease in pigs.
- Distinguishing T. hyodysenteriae from closely related non-pathogenic species like T. innocens is crucial for accurate diagnosis and control.
- Reliable in vivo models are needed for evaluating the virulence of Treponema isolates.
Purpose of the Study:
- To evaluate the CF1 strain female mouse as an in vivo model for assessing the virulence of Treponema hyodysenteriae.
- To determine if the CF1 mouse model can differentiate between virulent T. hyodysenteriae and non-virulent T. innocens isolates.
Main Methods:
- Fourteen T. hyodysenteriae and 11 T. innocens isolates from eight countries were used.
- CF1 mice were inoculated intragastrically with bacterial cultures after a 24-hour fast.
- Mice were necropsied 12-15 days post-inoculation to assess for caecitis and characteristic lesions.
Main Results:
- Caecitis was observed in 67% of mice inoculated with T. hyodysenteriae.
- No caecitis was detected in mice inoculated with T. innocens or sterile broth.
- Lesions in T. hyodysenteriae-infected mice included hyperaemia, mucosal oedema, inflammation, and haemorrhage.
Conclusions:
- The CF1 mouse model is a sensitive and specific in vivo system for detecting the virulence of T. hyodysenteriae.
- This model provides an inexpensive and effective means to differentiate between T. hyodysenteriae and T. innocens.
- The findings support the use of CF1 mice for routine virulence testing of Treponema isolates.