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Ultrastructure of Campylobacter jejuni in gamma-irradiated mouse jejunum
L Sosula1, E M Nicholls, M Skeen
1Department of Pathology, Prince of Wales Hospital, Australia.
Abstract:
This paper describes the ultrastructure of intracellular elongated, transitional and coccoid forms of Campylobacter jejuni, in irradiated mouse jejunum infected both in vitro and in vivo and in cultured human skin fibroblasts. Jejunum of irradiated mouse incubated for 1 hour under conditions favorable to the organisms showed minimal tissue degeneration. The intracellular organisms in this material were free cytoplasmic forms showing inner membrane degeneration, loss of cytoplasmic granules, and absence of flagella. The diameter of the coccoids was up to four times that of the elongated forms, as in plate cultures. Intracellular organisms were not found in challenged unirradiated controls, indicating that irradiation of mouse cells may be required for intracellular infection with human strains of C jejuni. In contrast, challenged human fibroblasts contained typical elongated organisms in cytoplasmic vacuoles. These findings are discussed with reference to Campylobacter strain, host resistance, and "natural" animal and human Campylobacter infections.
Insights
Irradiated mouse cells facilitate intracellular Campylobacter jejuni infection, revealing altered bacterial forms. Human fibroblasts harbor typical Campylobacter jejuni within vacuoles, suggesting varied host-pathogen interactions.
Area of Science:
- Microbiology
- Cell Biology
- Pathogenesis
Background:
- Campylobacter jejuni is a leading cause of bacterial gastroenteritis worldwide.
- Understanding C. jejuni's interaction with host cells is crucial for developing effective treatments.
- Previous studies have explored C. jejuni's extracellular and invasive properties.
Purpose of the Study:
- To investigate the ultrastructure of intracellular Campylobacter jejuni in various host cell models.
- To compare the morphology and location of C. jejuni within irradiated mouse jejunum and human fibroblasts.
- To elucidate the role of host cell irradiation in C. jejuni intracellular infection.
Main Methods:
- Transmission electron microscopy was used to examine C. jejuni ultrastructure.
- Infection models included irradiated mouse jejunum (in vitro and in vivo) and cultured human skin fibroblasts.
- Bacterial morphology and cellular localization were analyzed under favorable growth conditions.
Main Results:
- Intracellular C. jejuni in irradiated mouse jejunum exhibited degenerated inner membranes, lost granules, and lacked flagella, with coccoid forms enlarged.
- Irradiation of mouse cells appeared necessary for intracellular infection by human C. jejuni strains.
- Human fibroblasts contained elongated C. jejuni within cytoplasmic vacuoles, consistent with typical extracellular forms.
Conclusions:
- Host cell status, specifically irradiation, influences C. jejuni's intracellular survival and morphology.
- Differences in intracellular C. jejuni forms between mouse and human cells highlight host-specific interactions.
- Findings contribute to understanding Campylobacter strain variations, host resistance, and natural infections.