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Oral infection of immunocompetent and immunodeficient mice with Balamuthia mandrillaris amebae
Albrecht F Kiderlen1, Ulrike Laube, Elke Radam
1Cellular Immunology Unit, Robert Koch-Institut, Nordufer 20, 13353, Berlin, Germany. KiderlenA@rki.de
Abstract:
Balamuthia mandrillaris is an opportunistic agent of lethal granulomatous amebic encephalitis (GAE). In mice, we have shown that intranasally instilled B. mandrillaris amebae infect the brain via the olfactory nerve pathway. In this study, we raised the question whether this ameba might also reach the brain after an oral/gastrointestinal infection. Immunocompetent (WT) and immunodeficient (RAG) mice received B. mandrillaris amebae by gavage into the esophagus. Mice of both groups became ill and some died (WT 20%, RAG 40%) within 42 days. All orally infected mice revealed B. mandrillaris amebae in the central nervous system. Outwardly intact amebae and/or specific antigen were found widely distributed in various organs and the stool. The data indicate that oral infection with B. mandrillaris leading to GAE is possible. Exit from the gastrointestinal tract and dissemination remains unresolved. Though stool cultures were negative, transmission of this highly pathogenic ameba via stool cannot be ruled out.
Insights
Oral infection with Balamuthia mandrillaris (B. mandrillaris) can lead to lethal granulomatous amebic encephalitis (GAE). This study shows B. mandrillaris amebae can reach the brain after oral ingestion in mice.
Area of Science:
- Infectious Diseases
- Neuroscience
- Parasitology
Background:
- Balamuthia mandrillaris causes lethal granulomatous amebic encephalitis (GAE).
- Previous studies demonstrated intranasal infection leads to brain invasion via the olfactory nerve pathway in mice.
Purpose of the Study:
- To investigate if Balamuthia mandrillaris can infect the brain through oral/gastrointestinal routes.
- To determine the potential for GAE development following oral ingestion.
Main Methods:
- Immunocompetent (WT) and immunodeficient (RAG) mice were orally administered B. mandrillaris amebae via gavage.
- Mice were monitored for clinical signs, mortality, and presence of amebae in the central nervous system and other organs.
Main Results:
- Oral infection with B. mandrillaris led to illness and mortality in both WT (20%) and RAG (40%) mice within 42 days.
- B. mandrillaris amebae were detected in the central nervous system of all orally infected mice.
- Intact amebae and/or specific antigen were found in various organs and stool samples, indicating systemic dissemination.
Conclusions:
- Oral infection with B. mandrillaris is a viable route for developing GAE.
- The mechanisms of gastrointestinal tract exit and systemic dissemination require further investigation.
- While stool cultures were negative, the potential for stool-mediated transmission of this pathogen cannot be excluded.
