Related Experiment Videos
Assessment of protease (elastase) as a Pseudomonas aeruginosa virulence factor in experimental mouse burn infection
Abstract:
The data presented indicate that in experimental Pseudomonas aeruginosa infection of mice, protease enhances the virulence of the organism. Anesthetized CBA/Lü mice were subjected to a 15-s flame burn and infected with a wild-type protease-producing strain and two of its protease-deficient mutants. The average bacterial cell mean lethal dose (LD50) of 3.8 +/- 0.3 standard deviation (log10) for mice infected with the protease-producing P. aeruginosa was at least 1 log lower than the LD50 of the protease-deficient mutants (0.02 greater than P greater than 0.01). The addition of purified protease to the infecting inoculum of protease-deficient strains reduced the LD50. Although the generation time in vitro was the same for all three bacterial strains used, there were consistently fewer viable bacteria in the blood of mice infected with protease-deficient strains than in those infected with the protease-producing strain. When a protease-deficient strain was mixed with the protease-producing wild-type strain, the number of protease-producing pseudomonas found in the blood remained constant, whereas the number of protease-deficient organisms increased, suggesting that protease contributed to the invasiveness of the organisms. The survival of mice infected with protease-producing pseudomonas was enhanced by antiprotease serum. Antiprotease serum had no effect in mice infected with protease-deficient mutants.
Insights
Pseudomonas aeruginosa protease significantly increases virulence in mouse infection models. This bacterial protease enhances invasiveness and lowers the lethal dose, highlighting its role in pathogenesis.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Infectious Diseases
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen that causes severe infections.
- Bacterial proteases are virulence factors that can degrade host tissues.
- The role of P. aeruginosa protease in infection models requires further elucidation.
Purpose of the Study:
- To investigate the role of protease in the virulence of Pseudomonas aeruginosa.
- To determine if protease contributes to bacterial invasiveness and lethality.
- To assess the efficacy of antiprotease serum in an experimental infection model.
Main Methods:
- Experimental infection of burned mice with wild-type and protease-deficient P. aeruginosa strains.
- Determination of the mean lethal dose (LD50) for each strain.
- Assessment of bacterial load in blood and survival rates.
- Evaluation of the effect of purified protease and antiprotease serum.
Main Results:
- Protease-producing P. aeruginosa exhibited significantly lower LD50 values compared to protease-deficient mutants.
- Addition of purified protease to mutants reduced their LD50.
- Protease-deficient strains showed lower bacterial counts in blood.
- Antiprotease serum improved survival in mice infected with wild-type but not mutant strains.
Conclusions:
- Protease is a key virulence factor for Pseudomonas aeruginosa, enhancing its lethality and invasiveness.
- Targeting bacterial protease activity may be a therapeutic strategy against P. aeruginosa infections.
- The study confirms the contribution of protease to P. aeruginosa pathogenesis in a murine burn model.