title: Inhibition of host cell apoptosis by Eimeria bovis sporozoites.
abstract: Sophisticated evasion strategies of obligate intracellular parasites, in particular prevention of host cell apoptosis, are necessary to ensure successful replication. To study the ability of Eimeria bovis in this regard, in vitro experiments were performed applying bovine foetal gastrointestinal cells (BFGC), bovine umbilical vein endothelial cells (BUVEC) and African green monkey kidney cells (VERO) as host cells. BUVEC and BFGC allow maturation of sporozoites to macromeronts, in VERO cells sporozoites survive for weeks without showing further development. In highly infected BUVEC monolayers, infected cells survived until merozoite release whereas uninfected cells underwent apoptosis. Light microscopy and TUNEL assays performed 3-10 days p.i. showed that, within infected BFGC and VERO cell monolayers, uninfected cells underwent programmed cell death after application of various inducers of apoptosis, whereas infected cells survived. Incidentally, the anti-apoptotic efficacies in infected cells were independent of the drugs and the host cell type. We could not demonstrate significant differences between infected and uninfected cells after colchicin treatment in terms of translation of phosphatidylserines to the host cell surface, caspase 3 activity and cytochrome c release, probably since obtainable infection rates were too low. However, we could show by laser scanning confocal microscopy on single cell levels that the expression of the anti-apoptotic factors cellular Flice inhibitory protein (c-FLIP) and cellular inhibition of apoptosis protein 1 (c-IAP1) were enhanced in E. bovis infected cells after application of colchicin, in the latter case also in non-infected cells directly neighbouring infected ones. Our data show that E. bovis protects its host cell from apoptosis by increasing expression of c-IAP1 and c-FLIP.
authors.affiliation: Institute of Parasitology, Justus Liebig University Giessen, Germany.
authors.forename: Mirjam
authors.initials: M
authors.lastname: Lang
authors.forename: Michael
authors.initials: M
authors.lastname: Kann
authors.forename: Horst
authors.initials: H
authors.lastname: Zahner
authors.forename: Anja
authors.initials: A
authors.lastname: Taubert
authors.forename: Carlos
authors.initials: C
authors.lastname: Hermosilla
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000502:physiology*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002417:Cattle; D002522:Chlorocebus aethiops; D045304:Cytochromes c / Q000378:metabolism; D004539:Eimeria / Q000502:physiology*; D042783:Endothelial Cells / Q000469:parasitology*; D041981:Gastrointestinal Tract / Q000166:cytology*; D005786:Gene Expression Regulation / Q000502:physiology; D014709:Vero Cells
chemical_list: D017304:Annexin A5; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D045304:Cytochromes c; D053148:Caspase 3