A lethal pneumonia model of Acinetobacter baumannii: an investigation in immunocompetent mice
1National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Army Medical University, Chongqing, China.
Objectives:
Acinetobacter baumannii can cause severe nosocomial and community-acquired pneumonia. To study the pathogenesis of A. baumannii and to develop new treatments, appropriate mouse models are needed. Most reported mouse models of pulmonary A. baumannii infection are non-lethal or require mouse immunosuppression to enhance infection. These models are not suitable for studying host immune responses or evaluating immunotherapies.
Methods:
The virulence of 30 clinical isolates was assessed in mice. The most virulent isolate, SJZ24, was selected to develop a pneumonia model in immunocompetent mice. The cytokine mRNA expression in the lung was assessed with real-time PCR. The cell infiltration in bronchoalveolar lavage fluid (BALF) after SJZ24 infection was determined by flow cytometry. Vaccine efficacy was assessed using this model.
Results:
Intratracheal inoculation of SJZ24 (5 × 107 CFU) resulted in death in 100% of the mice (5/5). SJZ24-infected mice showed high bacterial burdens in blood and organs as well as severe lung-tissue damage. Infection with SJZ24 induced increased inflammatory cytokine expression in the lung and increased neutrophil infiltration in BALF. Immunization with inactivated whole cells of SJZ24 showed 100% protection (5/5) against A. baumanni infection in this model.
Conclusions:
We established a lethal pneumonia model in immunocompetent mice with hypervirulent A. baumannii isolate SJZ24. This model can be used to study the immune response to A. baumannii infection and to evaluate vaccine efficacy.
Insights
A new lethal pneumonia model in immunocompetent mice was developed using the hypervirulent Acinetobacter baumannii isolate SJZ24. This model is effective for studying immune responses and evaluating vaccines against A. baumannii infections.
Area of Science:
- Microbiology
- Immunology
- Pathogenesis
Background:
- Acinetobacter baumannii causes severe pneumonia, necessitating effective mouse models for research.
- Existing models are often non-lethal or require immunosuppression, limiting their utility for studying host immunity and therapies.
Purpose of the Study:
- To establish a lethal pneumonia model in immunocompetent mice using a hypervirulent A. baumannii isolate.
- To evaluate the utility of this model for studying host immune responses and assessing vaccine efficacy.
Main Methods:
- Assessed virulence of 30 clinical A. baumannii isolates in mice.
- Selected the most virulent isolate, SJZ24, for model development.
- Analyzed cytokine mRNA expression, bronchoalveolar lavage fluid cell infiltration, and vaccine efficacy.
Main Results:
- Intratracheal inoculation with SJZ24 (5 × 10^7 CFU) caused 100% mortality in immunocompetent mice.
- Infected mice exhibited high bacterial loads, organ damage, lung inflammation, and neutrophil infiltration.
- Vaccination with inactivated SJZ24 provided 100% protection against lethal infection.
Conclusions:
- A lethal pneumonia model in immunocompetent mice was successfully established using A. baumannii SJZ24.
- This model is suitable for investigating the immune response to A. baumannii and evaluating potential vaccines.
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