In vitro activity of the human neutrophil cathepsin G on Eimeria tenella sporozoites.
The role of human neutrophil cathepsin G (Cat G) on Eimeria tenella sporozoites was studied in vitro. Sporozoites were incubated for 2 hr at 37 C in PO4 buffer, 0.9% NaCl (PBS), pH 7.6 in the presence of Cat G (50 micrograms/ml), diisopropyl fluorophosphate-inhibited Cat G (DFP-Cat G) (50 micrograms/ml) or PBS alone, prior to being inoculated into embryonated eggs. As judged by oocyst production on day 7 postinoculation, embryo mortality and the hemorrhage scores, both Cat G and DFP-Cat G demonstrated anticoccidial activity; greater activity was obtained with the DFP-Cat G. Sporozoites were exposed also to increasing concentrations of native and trypsin-digested DFP-Cat G (0-100 micrograms/ml) under the same conditions. Significant protection (37% and 49% for native and digested DFP-Cat G, respectively) was obtained with a low concentration (5 mu/ml), and higher concentrations resulted in 70% and 84% protection, respectively. The primary bactericidal domain of Cat G, the HPQYNQR peptide, at 3 concentrations (25, 50, and 100 micrograms/ml), reduced the oocyst production by 46%, 16%, and 15%, respectively. The anticoccidial activity of Cat G may involve a peptide fragment different from the antimicrobial domain of the enzyme.
Guyonnet
V
V
Department of Poultry Science, University of Georgia, Athens 30602.
Johnson
J K
JK
Bangalore
N
N
Travis
J
J
Long
P L
PL
D000595:Amino Acid Sequence; D000818:Animals; D056649:Cathepsin G; D002403:Cathepsins / Q000737:chemistry / Q000494:pharmacology*; D016786:Eimeria tenella / Q000187:drug effects*; D006801:Humans; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000276:immunology*; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D012697:Serine Endopeptidases
D010446:Peptide Fragments; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G