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Factors affecting infectivity of Tyzzer's organism in cultured mouse hepatocytes
S Kawamura1, T Mitsuoka, K Fujiwara
1Department of Biomedical Science, Faculty of Agriculture, University of Tokyo, Japan.
Abstract:
Factors affecting the infectivity of Tyzzer's organism, an obligate intracellular bacterium, were examined in cultured mouse hepatocytes. The organisms were subjected to physical and chemical impairments and the infectivity was estimated by immunofluorescence that discriminated adhesion and entry of the organisms to host cells and by the plaque assay. Pretreatment of the organisms with either mild heat or formalin abolished adhesion. UV irradiation completely removed the plaque forming ability, while adhering and entering capacity were more resistant in this order. Entry of the organism into host cells was suppressed in the presence of erythromycin, gentamicin or oxytetracycline, while it was relatively little susceptible to ampicillin, kanamycin or rifampicin. Plaquing efficiencies were increased by centrifugation during the infection. These results suggest that not only a structural but also a functional integrity of the organisms was requisite for establishment of the infection at the initial stage.
Insights
Tyzzer
Area of Science:
- Microbiology and Infectious Diseases
- Cell Biology
- Bacteriology
Background:
- Tyzzer's organism is an obligate intracellular bacterium.
- Understanding its infectivity is crucial for disease control.
Purpose of the Study:
- To investigate factors influencing the infectivity of Tyzzer's organism.
- To determine the effects of physical and chemical agents on bacterial adhesion and entry into host cells.
Main Methods:
- Cultured mouse hepatocytes were used as host cells.
- Immunofluorescence assays were employed to assess bacterial adhesion and entry.
- Plaque assays were utilized to measure infectivity.
- Organisms were subjected to various physical (heat, UV irradiation) and chemical (antibiotics) treatments.
Main Results:
- Mild heat or formalin treatment abolished bacterial adhesion.
- UV irradiation eliminated plaque-forming ability, but adhesion and entry were more resistant.
- Antibiotics like erythromycin, gentamicin, and oxytetracycline suppressed bacterial entry.
- Centrifugation during infection enhanced plaquing efficiencies.
Conclusions:
- Both structural and functional integrity of Tyzzer's organism are essential for initial infection establishment.
- Specific antibiotics can inhibit bacterial entry into host cells.
- Physical treatments impact different stages of the infection process differently.