Effects of host temperature and gastric and duodenal environments on microsporidia spore germination and infectivity of intestinal epithelial cells

Abstract

Approximately 14 of the more than 1,000 species of microsporidia infect humans, only 2 of which, Enterocytozoon bieneusi and Encephalitozoon intestinalis, cause intestinal microsporidiosis. Clinical isolates of three microsporidia species, E. intestinalis, Encephalitozoon hellem, and the insect parasite, Anncaliia (Brachiola, Nosema) algerae were used in a spore germination assay, and enterocyte attachment and infection assays to model the potential roles of gastric and duodenal environments, and host temperature in determining why only one of these microsporidia species causes intestinal microsporidiosis. Enterocyte infection with A. algerae spores was 10% that of the Encephalitozoon species, a difference not attributable to differences in spore attachment to host cells. Prior spore treatment with pepsin in HCl, pancreatic enzymes or ox bile did not inhibit germination or enterocyte infection by the three microsporidia species. While the Encephalitozoon species differentiated to mature spores within 3 days, the time taken for many enterocytes to turn over, A. algerae took 3 -5 days to produce mature spores, near the upper limit for enterocyte turnover in vivo. Thus host temperature may contribute to A. algerae not causing human intestinal microsporidiosis, but none of the factors tested account for the inability of E. hellem to cause such an infection.

In vitro growth of microsporidia Anncaliia algerae in cell lines from warm water fish

“…Common cell types supporting infection have been kidney epithelial cells (Undeen 1975;Lowman et al 2000;Takvorian et al 2005); African Green monkey (Kucerova et al 2004) and fibroblasts from human lung, muscle, and foreskin (Scanlon et al 1999;Trammer et al 1999;Belkorchia et al 2008) and from Xenopus (Smith et al 1982). Also used successfully to grow A. algerae have been cells or cell lines from rat brain and skeletal muscle (Smith and Sinden 1980;Smith et al 1982;Cali et al 2004), human intestine (Leitch and Ceballos 2008), and liver (Smith et al 1982). For the warm water fish, cell lines from embryo, brain, testis, and skin became infected with A. algerae, but the skin cell line, GFSK-S1 appeared to be better at supporting the production of A. algerae life cycle stages at 6 d post-infection.…”

“…For the warm water fish, cell lines from embryo, brain, testis, and skin became infected with A. algerae, but the skin cell line, GFSK-S1 appeared to be better at supporting the production of A. algerae life cycle stages at 6 d post-infection. Other hints of cell type preference were seen in the poor infection of differentiated human intestinal epithelial cells (Leitch and Ceballos 2008) and in the severe infection of the liver but not in other tissues of immunodeficient mice (Koudela et al 2001). In the future, the in vitro approach might allow the delineation of possible tissue or cell selectivity.…”

“…For this route, the fish GI tract would have to allow spore germination and sporoplasm penetration into epithelial cells. Although no clinical cases have been seen to involve the GI tract, A. algerae has been shown to infect the human intestinal cell line, CaCo-2 (Leitch and Ceballos 2008).…”

Seminal fluid of honeybees contains multiple mechanisms to combat infections of the sexually transmitted pathogen Nosema apis

“…Interestingly, we found that the protein fraction of seminal fluid induced the germination of N. apis spores. Germination of microsporidia, such as Nosema, can be caused by a number of factors such as changes in pH, temperature, ionic concentrations or exposure of dehydrated spores to water [37,[40][41][42]. Regardless of the trigger, spore germination results from an increase of osmotic pressure inside the spore that eventually triggers the expulsion of the polar tube [41][42][43], but the exact mechanisms are still unknown.…”

Identification of NbME MITE families: Potential molecular markers in the microsporidia Nosema bombycis

“…The infection abilities of the spores were assayed by counting the number of infected Sf9 cells based on a protocol adapted from Leitch and Ceballos (2008). Briefly, 1 Â 10 5 cell were cultured on 3.8-cm 2 transwells and maintained at 28°C in Dulbecco's modified Eagle's medium supplemented with 10 lg/ml human transferrin and 10% fetal bovine serum.…”