Experimental infection of murine and human macrophages with Cystoisospora belli

Abstract

Extraintestinal cystoisosporosis by Cystoisospora belli has already been reported in HIV/AIDS patients, generally involving preferential invasion of mesenteric and trachaeobronchial lymph nodes, liver and spleen by unizoic cysts of this parasite, which may infect macrophages. To test this hypothesis, murine and human macrophages were exposed to sporozoites of C. belli and cultures were observed daily after contact with these cells. The parasites penetrated and multiplied by endodyogeny in both cell types and inserted themselves inside perinuclear vacuoles. After 48 h, extracellular parasites were removed from macrophage cultures and incubated in Monkey Kidney Rhesus cells (MK2) where there was intense multiplication. This is the first report of infection of macrophages by this parasite, which supports the hypothesis that these could act as C. belli host cells in extraintestinal sites.

Ultrastructural aspects of Cystoisospora belli (syn. Isospora belli) in continuous cell lines

“…The ultrastructural features of C. belli zoites were similar to those described in hypnozoites of C. belli from biopsies of HIV/AIDS patients (Comin and Santucci, 1994;Michiels et al, 1994;Restrepo et al, 1987;Vel asquez et al, 2001) and other Cystoisospora species (Dubey and Mehlhorn, 1978;Lindsay et al, 1991;Mitchell et al, 2009;Roberts et al, 1972), which suggests that similar mechanisms of interaction and cellular invasion may occur among parasites of the Apicomplexa Phylum. C. belli is able to infect and multiply in different cell types (Oliveira-Silva et al, 2006;Resende et al, 2009;Siripanth et al, 2004), which demonstrates that zoites recognize different patterns of adhesion receptors on the cell surface or even one standard receptor widely expressed in animal cells.…”

“…The intracellular development of various species of Isospora and Cystoisospora in cell cultures observed under light microscopy shows the penetration of sporozoites into host cells and the formation of meronts by endodyogeny (Fayer and Mahrt, 1972;Fayer and Thompson, 1974;Fayer, 1972;Guiti errez and Arcay, 1987;Lindsay and Blagburn, 1987;Lindsay and Current, 1984;Oliveira-Silva et al, 2006;Resende et al, 2009;Siripanth et al, 2004). However, there are no ultrastructural studies on the in vitro development of C. belli.…”

Diarrea recurrente por Cystoisopora belli en pacientes con infección por VIH con TARGA

“…Estos sitios extraintestinales pueden representar focos de reservorio de C. belli que pueden recolonizar el intestino y causar recrudescencia de la enfermedad clínica, que sumado a la pobre concentración tisular del TMP/SMX en estos tejidos hacen que estos casos sean difíciles de controlar (9,10) . Al respecto, se puede añadir que los esporozoitos de C. belli pueden sobrevivir y multiplicarse dentro de los macrófagos; por lo que estas células puede hospedar formas quísticas unizoicas de este coccidio en sitios extraintestinales para luego retornar al intestino delgado y reiniciar el proceso patogénico (11) .…”

Cystoisospora Species Insights From Development in vitro

“…The authors found no crystalloid bodies in merozoites of C. belli as are present in C. suis (24) while undergoing endodyogeny in vitro but otherwise the structural findings were similar to those reported for C. suis . Stages of C. belli obtained from macrophage cell cultures were infectious for RMK cells upon subinoculation and development by endodyogeny occurred (31) but MZTC were not reported.…”