Encephalitozoon cuniculi
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| Levaditi , Nicolau & Schoen |
Encephalitozoon cuniculi (formerly also known as Nosema cuniculi ) is a parasitic single-cell organism that livesintracellularly in the kidneys , brain and other organs. It is assigned to the microsporidia , the exact systematic position of this parasite has not yet been finally clarified. It is the causative agent of encephalitozoonosis , adisease thatoccurs mainly in rabbits , old-world mice and dogs andwhich can also be transmitted to people with an immunodeficiency.
Classification
The genome of E. cuniculi is 2.9 Mbp in size and is distributed over 11 chromosomes with sizes between 217 and 315 kbp. E. cuniculi is now divided into three genetically and serologically distinguishable strains. Morphologically, these three variants cannot be distinguished. They are named as Type I to III or after their main host:
- Type I (rabbit strain) is common in Europe, especially in domestic rabbits. It is also pathogenic to humans, while dogs are believed to be resistant to this strain.
- Type II (mouse strain) is pathogenic for Old World mice . Fatal infections in farm foxes have also been observed in Scandinavia . In cats , eye infections (phacoclastic uveitis, focal lens opacification , anterior uveitis) occur in particular .
- Type III (dog strain) is particularly widespread in North America and South Africa and mainly affects dogs. Infections in monkeys have also been observed in European zoos .
morphology
Encephalitozoon cuniculi can be seen in histological specimens as a 2–2.5 × 0.8–1.2 µm large, slightly curved rod with rounded ends. The pathogen is missing some cell organelles , such as B. Mitochondria .
Outside the host cells, the pathogen occurs as an infectious permanent stage in the form of a spore . The approximately 2 µm large spores consist of an outer ( exospore ) and a thicker, chitin-rich inner layer ( endospore ). In the cell plasma of the spore ( sporoplasm ) there is a spiral-wound pile thread.
Development cycle
The host is infected via spores. Encephalitozoon cuniculi has an infection mode that only occurs in microsporidia: the pile thread is everted, penetrates the cell membrane and injects the sporoplasm into the host cell. However, the spore reaches a scavenger cell ( macrophage ) about 10 times more often through normal phagocytosis . Then, as a sign of the germination of the spore, the pile thread is only everted inside the scavenger cell, which prevents the development of the phagosomes in lysosomes and thus their breakdown.
In the host cell's cytoplasm there is multiple asexual reproduction ( merogony ) and finally spore formation. Up to 100 sporoblasts per cell can occur. The exact way in which the pathogen spreads in the host is not yet known. The pathogen mainly affects the kidneys and the brain . The infectious spores are excreted in the urine .
The spores are very resistant to the environment. At 25 ° C they are infectious for three weeks, at 10 ° C for three months. At 100 ° C they are inactivated after 5 minutes. For disinfection to boiling water, 2% are Lysol , 1% formaldehyde or 70% alcohol .
literature
- Thomas Schnieder (Ed.): Veterinary Parasitology . Paul Parey, 2006. ISBN 3-8304-4135-5
Individual evidence
- ↑ N. Dia, L. Lavie, N. Faye, G. Méténier, E. Yeramian, C. Duroure, BS Toguebaye, R. Frutos, MN Niang, CP Vivarès, C. Ben Mamoun, E. Cornillot: Subtelomere organization in the genome of the microsporidian Encephalitozoon cuniculi: patterns of repeated sequences and physicochemical signatures. In: BMC genomics. Volume 17, number 1, 2016, p. 34, doi : 10.1186 / s12864-015-1920-7 , PMID 26744270 , PMC 4704409 (free full text).
- ↑ Petra Benz et al .: Detection of Encephalitozoon cuniculi in the feline cararactous lens . In: Veterinary ophthalmology 14 (2011), Suppl. 1, pp. 37-47.
- ↑ Taupin, V. et al .: Expression of two cell wall proteins during the intracellular development of Encephalitozoon cuniculi: an immunocytochemical and in situ hybridization study with ultrathin frozen sections. Parasitology. 2006 Jun; 132 (Pt 6): 815-25. Epub 2006 Feb 10. PMID 16469199
- ↑ Franzen, C. et al .: Cell invasion and intracellular fate of Encephalitozoon cuniculi (Microsporidia). Parasitology. 2005 Mar; 130 (Pt 3): 285-92. PMID 15796011