Opportunistic properties of insect microsporidia

Abstract number: 1733_25

Franzen C., Fischer S., Schölmerich J., Schneuwly S., Salzberger B.

Objectives: Tubulinosema ratisbonensis is a microsporidian pathogen of the fruit fly Drosophila melanogaster belonging to the family Tubulinosematidae. The microsporidia in this family mainly cause infections in invertebrate hosts, but two members of this family, Anncaliia vesicularum and Anncaliia algerae, have been found as cause of infections in humans as well. Moreover, A. algerae could be transmitted to immunodeficient mice and grows in mammalian cell cultures. Thus, the examination of the opportunistic properties of other members of the family Tubulinosematidae is mandatory.

Methods: Spores of T. ratisbonensis, isolated from infected fruit flies, were inoculated on mammalian and insect cell cultures and in immunodeficient mice [NMRI (nu/nu)] (n = 24) at different locations (tail, neck, i.p., eye, leg, oral). On day 60 post infection all mice were euthanised and necropsied. Cultures and mice were examined by light microscopy, scanning and transmission electron microscopy, and by PCR and subsequent DNA sequencing.

Results: In cell cultures parasite growth was only seen in human lung fibroblasts whereas no growth was seen in Vero cells or insect cell cultures. Transmission electron microscopy showed the typical ultrastructure of T. ratisbonensis and scanning electron microscopy showed oval or slightly pyriform spores with some spores having extruded their polar tubes. Sequencing of PCR-fragments, amplified from infected cell cultures, reveals DNA sequences that were 100% identical with the original T. ratisbonensis rRNA sequence. All 24 mice survived the 60 days study period without clear signs of disease. All examined internal organs were free from microsporidia but limited growth was seen at sites with lower body temperature (tail, leg).

Conclusion: As T. ratisbonensis is able to proliferate in mammalian cells and in immunodeficient mice at sites with lower body temperature, it might have opportunistic properties like other members of the family Tubulinosematidae.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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