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MICROBIC VIRULENCE AND HOST SUSCEPTIBILITY IN MOUSE TYPHOID INFECTION
1Laboratories of The Rockefeller Institute for Medical Research.
Abstract:
Mice bred at The Rockefeller Institute vary in their susceptibility to mouse typhoid infection caused by a certain strain of Bacillus pestis caviae. This graded variation may be roughly analyzed as follows: in any series infected per os with a fixed dose, 20 to 30 per cent show no sign of infection, no positive blood cultures, and no agglutinins; 5 or 10 per cent present symptoms of disease, positive blood cultures, and then recover with or without homologous agglutinins; 70 or 80 per cent develop positive blood cultures and succumb in a more or less constant ratio relative to time. The strain of Bacillus pestis caviae employed throughout a 10 month series of experiments has shown no permanent change in virulence. Blood cultures taken from infected mice early in disease, shortly after death, and 6 days after death, chronic stool carrier cultures, and chronic septicemia cultures, all show approximately the same degree of virulence.
Insights
Mouse typhoid infection susceptibility varies among mice. Most mice succumb to Bacillus pestis caviae, while a small percentage recover or show no infection, indicating graded resistance.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- Mouse typhoid, caused by Bacillus pestis caviae, affects mice differently.
- Understanding host susceptibility is crucial for disease research.
Purpose of the Study:
- To analyze the graded variation in mouse susceptibility to Bacillus pestis caviae.
- To determine the virulence stability of the bacterial strain over time.
Main Methods:
- Infection of mice per os with a fixed dose of Bacillus pestis caviae.
- Monitoring for signs of infection, positive blood cultures, and agglutinins.
- Assessing bacterial virulence through various culture methods (blood, stool, septicemia).
Main Results:
- 20-30% of mice showed no infection.
- 5-10% of mice recovered from infection.
- 70-80% of mice succumbed to infection.
- The Bacillus pestis caviae strain maintained consistent virulence over 10 months.
Conclusions:
- Mouse susceptibility to Bacillus pestis caviae infection is graded.
- The bacterial strain's virulence remained stable throughout the experimental period.
