A cysteine protease inhibitor rescues mice from a lethal Cryptosporidium parvum infection.
Cryptosporidiosis, caused by the protozoan parasite Cryptosporidium parvum, can stunt infant growth and can be lethal in immunocompromised individuals. The most widely used drugs for treating cryptosporidiosis are nitazoxanide and paromomycin, although both exhibit limited efficacy. To investigate an alternative approach to therapy, we demonstrate that the clan CA cysteine protease inhibitor N-methyl piperazine-Phe-homoPhe-vinylsulfone phenyl (K11777) inhibits C. parvum growth in mammalian cell lines in a concentration-dependent manner. Further, using the C57BL/6 gamma interferon receptor knockout (IFN-γR-KO) mouse model, which is highly susceptible to C. parvum, oral or intraperitoneal treatment with K11777 for 10 days rescued mice from otherwise lethal infections. Histologic examination of untreated mice showed intestinal inflammation, villous blunting, and abundant intracellular parasite stages. In contrast, K11777-treated mice (210 mg/kg of body weight/day) showed only minimal inflammation and no epithelial changes. Three putative protease targets (termed cryptopains 1 to 3, or CpaCATL-1, -2, and -3) were identified in the C. parvum genome, but only two are transcribed in infected mammals. A homology model predicted that K11777 would bind to cryptopain 1. Recombinant enzymatically active cryptopain 1 was successfully targeted by K11777 in a competition assay with a labeled active-site-directed probe. K11777 exhibited no toxicity in vitro and in vivo, and surviving animals remained free of parasites 3 weeks after treatment. The discovery that a cysteine protease inhibitor provides potent anticryptosporidial activity in an animal model of infection encourages the investigation and development of this biocide class as a new, and urgently needed, chemotherapy for cryptosporidiosis.
National Reference Centre for Parasitology, Research Institute of the McGill University Health Center, Montreal, Canada.
Momar
M
Ndao
Milli
M
Nath-Chowdhury
Mohammed
M
Sajid
Victoria
V
Marcus
Susan T
ST
Mashiyama
Judy
J
Sakanari
Eric
E
Chow
Zachary
Z
Mackey
Kirkwood M
KM
Land
Matthew P
MP
Jacobson
Chakrapani
C
Kalyanaraman
James H
JH
McKerrow
Michael J
MJ
Arrowood
Conor R
CR
Caffrey
D000284:Administration, Oral; D000818:Animals; D000981:Antiprotozoal Agents / Q000737:chemistry / Q000494:pharmacology*; D003457:Cryptosporidiosis / Q000188:drug therapy* / Q000401:mortality / Q000469:parasitology; D016785:Cryptosporidium parvum / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D057056:Cysteine Proteases / Q000737:chemistry / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D004151:Dipeptides / Q000737:chemistry / Q000494:pharmacology*; D004334:Drug Administration Schedule; D005260:Female; D007274:Injections, Intraperitoneal; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D062105:Molecular Docking Simulation; D010649:Phenylalanine / Q000031:analogs & derivatives; D010879:Piperazines; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D017471:Receptors, Interferon / Q000172:deficiency / Q000235:genetics; D016019:Survival Analysis; D014105:Tosyl Compounds; D014753:Vinyl Compounds / Q000737:chemistry / Q000494:pharmacology*; D000096743:Interferon gamma Receptor
D000981:Antiprotozoal Agents; D057056:Cysteine Proteases; D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides; D007527:Isoenzymes; D010649:Phenylalanine; D010879:Piperazines; D015800:Protozoan Proteins; D017471:Receptors, Interferon; D014105:Tosyl Compounds; D014753:Vinyl Compounds; D000096743:Interferon gamma Receptor; C487484:N-pip-phenylalanine-homophenylalanine-vinyl sulfone phenyl