title: Glycoproteins and Gal-GalNAc cause Cryptosporidium to switch from an invasive sporozoite to a replicative trophozoite.
abstract: The apicomplexan parasite Cryptosporidium causes cryptosporidiosis, a diarrheal disease that can become chronic and life threatening in immunocompromised and malnourished people. There is no effective drug treatment for those most at risk of severe cryptosporidiosis. The disease pathology is due to a repeated cycle of host cell invasion and parasite replication that amplifies parasite numbers and destroys the intestinal epithelium. This study aimed to better understand the Cryptosporidium replication cycle by identifying molecules that trigger the switch from invasive sporozoite to replicative trophozoite. Our approach was to treat sporozoites of Cryptosporidium parvum and Cryptosporidium hominis, the species causing most human cryptosporidiosis, with various media under axenic conditions and examine the parasites for rounding and nuclear division as markers of trophozoite development and replication, respectively. FBS had a concentration-dependent effect on trophozoite development in both species. Trophozoite development in C. parvum, but not C. hominis, was enhanced when RPMI supplemented with 10% FBS (RPMI-FBS) was conditioned by HCT-8 cells for 3h. The effect of non-conditioned and HCT-8 conditioned RPMI-FBS on trophozoite development was abrogated by proteinase K and sodium metaperiodate pretreatment, indicating a glycoprotein trigger. Cryptosporidium parvum and C. hominis trophozoite development also was triggered by Gal-GalNAc in a concentration-dependent manner. Cryptosporidium parvum replication was greatest following treatments with Gal-GalNAc, followed by conditioned RPMI-FBS and non-conditioned RPMI-FBS (P<0.05). Cryptosporidium hominis replication was significantly less than that in C. parvum for all treatments (P<0.05), and was greatest at the highest tested concentration of Gal-GalNAc (1mM).
authors.affiliation: Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, ND, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Edwinson
authors.affiliation: Cummings School of Veterinary Medicine at Tufts University, Division of Infectious Diseases & Global Health, North Grafton, MA, USA.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Widmer
authors.affiliation: Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, ND, USA. Electronic address: john.mcevoy@ndsu.edu.
authors.forename: John
authors.initials: J
authors.lastname: McEvoy
mesh_terms: D000818:Animals; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000494:pharmacology*; D002460:Cell Line; D048750:Cell Nucleus Division / Q000187:drug effects; D003457:Cryptosporidiosis / Q000469:parasitology; D003458:Cryptosporidium / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity; D016785:Cryptosporidium parvum / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D019286:Endopeptidase K / Q000494:pharmacology; D006023:Glycoproteins / Q000494:pharmacology*; D006790:Host-Parasite Interactions; D006801:Humans; D007413:Intestinal Mucosa / Q000469:parasitology / Q000473:pathology; D051379:Mice; D010504:Periodic Acid / Q000494:pharmacology; D011134:Polysaccharides / Q000378:metabolism; D015800:Protozoan Proteins / Q000378:metabolism; D034101:Sporozoites / Q000187:drug effects; D053058:Trophozoites / Q000187:drug effects
chemical_list: D015295:Antigens, Tumor-Associated, Carbohydrate; D006023:Glycoproteins; D011134:Polysaccharides; D015800:Protozoan Proteins; D010504:Periodic Acid; C016467:Thomsen-Friedenreich antigen; C009288:metaperiodate; D019286:Endopeptidase K
keywords: Asexual replication; Cryptosporidium; Glycan; Glycoprotein; HCT-8 cells; Sporozoite; Trophozoite