Uptake of Encephalitozoon spp. and Vittaforma corneae (Microsporidia) by different cells

Microsporidia are obligate intracellular parasites infecting a broad range of vertebrates and invertebrates. Various microsporidian species induce different clinical pictures in humans. The reason for this is not clear. It has been speculated that the different microsporidian species are transmitted by various routes, thus causing infections in different organs. Another possibility is that the diverse microsporidia have different tropisms to organ-specific cells, thus causing various diseases. In this study, we investigated the uptake of microsporidian spores by different cells with an immunofluorescence staining technique to investigate whether there is a difference between microsporidian species as well as between different cells. Using this technique, we were able to distinguish between intra- and extracellular microsporidian spores. All examined cell lines were able to internalize microsporidian spores, but the extent of internalization differed significantly between the cells. Although the results showed some patterns that correlate with the distribution of the parasites in humans, the different clinical pictures cannot be sufficiently explained by this phenomenon, so it seems more likely that the various clinical manifestations caused by the different microsporidian species are a consequence of different infection routes rather than of different affinities of the microsporidian species to different cells.