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Published on: February 19, 2013
Ultrastructural changes in a standard strain of Bartonella henselae after passages through BALB/cAn mice
Paulo Eduardo Neves Ferreira Velho1, Aparecida Machado de Moraes, Ana Maria Uthida-Tanaka
1Department of Internal Medicine, Medical School Sciences, State University of Campinas-FCM/UNICAMP, SP, Brazil. pvelho@obelix.unicamp.br
Abstract:
Human bartonelloses are a group of illnesses of poorly understood pathogenesis. Bartonella henselae is one of the most studied bacterium of its genus. The objective of this study was to observe whether passages of these bacteria, in vivo, would determine ultrastructural changes in them. For this purpose, isogenic mice were inoculated with a standard strain of B. henselae (I). These were initially retrieved from genetically immunodeficient animals (II) and then inoculated in immunocompetent ones. The bacterial colonies obtained (III) were compared, by transmission electron microscopy, with colonies I and II. Loss of fimbriae and an abundant bleb formation were the most common morphological changes found in colony III. Also, on day 6 postinfection, the main histological abnormalities were the endothelial proliferation presented in immunodeficient animals and the incipient granulomata reaction found in one of the immunocompetent inoculated mice, which died spontaneously. These features agree with the Bartonella human disease clinical and histological observations. This study demonstrates that B. henselae in vivo passages induce significant morphological changes in the bacteria and that these abnormalities could explain their seemingly greater virulence. Most of these observations have not been previously described. Thus, further studies on the Bartonella species pathogenesis should consider these data.
Insights
Passaging Bartonella henselae bacteria in mice caused significant ultrastructural changes, including loss of fimbriae and bleb formation. These bacterial alterations may explain increased virulence in Bartonella henselae infections.
Area of Science:
- Microbiology
- Pathogenesis
- Bacteriology
Background:
- Human bartonelloses are infectious diseases with poorly understood pathogenesis.
- Bartonella henselae is a frequently studied bacterium within its genus.
Purpose of the Study:
- To investigate if in vivo passages of Bartonella henselae induce ultrastructural changes in the bacteria.
- To correlate observed bacterial morphological changes with host responses and virulence.
Main Methods:
- Inoculation of isogenic mice with a standard Bartonella henselae strain.
- Retrieval of bacteria from immunodeficient and subsequent inoculation into immunocompetent mice.
- Comparison of bacterial colonies using transmission electron microscopy and histological analysis.
Main Results:
- Passaged Bartonella henselae (colony III) exhibited significant morphological changes, including loss of fimbriae and abundant bleb formation, compared to initial strains (colonies I and II).
- Histological findings included endothelial proliferation in immunodeficient mice and incipient granulomata in an immunocompetent mouse.
- Observed changes align with clinical and histological features of human bartonelloses.
Conclusions:
- In vivo passages of Bartonella henselae induce notable morphological alterations in the bacteria.
- These bacterial abnormalities are proposed as a mechanism contributing to increased virulence.
- The study highlights previously undescribed observations relevant for future Bartonella pathogenesis research.
