Several studies have reported that the citrus red mites Panonychus citri were an important allergen of citrus-cultivating farmers in Jeju Island. The aim of the present study was to purify and assess properties of a cysteine protease from the mites acting as a potentially pathogenic factor to citrus-cultivating farmers. A cysteine protease was purified using column chromatography of Mono Q anion exchanger and Superdex 200 HR gel filtration. It was estimated to be 46 kDa by gel filtration column chromatography and consisted of 2 polypeptides, at least. Cysteine protease inhibitors, such as trans poxy-succinyl-L-leucyl-amido (4-guanidino) butane (E-64) and iodoacetic acid (IAA) totally inhibited the enzyme activities, whereas serine or metalloprotease inhibitors did not affect the activities. In addition, the purified enzyme degraded human IgG, collagen, and fibronectin, but not egg albumin. From these results, the cysteine protease of the mites might be involved in the pathogenesis such as tissue destruction and penetration instead of nutrient digestion.
Animals ; Chromatography, Gel ; Chromatography, Ion Exchange ; Collagen/metabolism ; Cysteine Proteases/chemistry/*isolation & purification ; Cysteine Proteinase Inhibitors/metabolism ; Fibronectins/metabolism ; Humans ; Immunoglobulin G/metabolism ; Molecular Weight ; Protein Subunits/chemistry/isolation & purification ; Proteolysis ; Substrate Specificity ; Tetranychidae/*enzymology

Fascioliasis is one of the public health problems in the world. Cysteine proteinases (CP) released by Fasciola gigantica play a key role in parasite feeding, migration through host tissues, and in immune evasion. There has been some evidence from several parasite systems that proteinases might have potential as protective antigens against parasitic infections. Cysteine proteinases were purified and tested in vaccine trials of sheep infected with the liver fluke. Multiple doses (2 mg of CP in Freund's adjuvant followed by 3 booster doses 1 mg each at 4 week intervals) were injected intramuscularly into sheep 1 week prior to infect orally with 300 F. gigantica metacercariae. All the sheep were humanely slaughtered 12 weeks after the first immunization. Changes in the worm burden, ova count, and humoral and cellular responses were evaluated. Significant reduction was observed in the worm burden (56.9%), bile egg count (70.7%), and fecel egg count (75.2%). Immunization with CP was also found to be associated with increases of total IgG, IgG1, and IgG2 (P<0.05). Data showed that the serum cytokine levels of pro-inflammatory cytokines, IL-12, IFN-gamma, and TNF-alpha, revealed significant decreases (P<0.05). However, the anti-inflammatory cytokine levels, IL-10, TGF-beta, and IL-6, showed significant increases (P<0.05). In conclusion, it has been found that CP released by F. gigantica are highly important candidates for a vaccine antigen because of their role in the fluke biology and host-parasite relationships.
Animals ; Antibodies, Helminth/immunology ; Cysteine Proteases/administration & dosage/*immunology/isolation & purification ; Cytokines/immunology ; Fasciola/chemistry/*enzymology/immunology ; Fasciola hepatica/immunology/physiology ; Fascioliasis/immunology/parasitology/*prevention & control ; Female ; Helminth Proteins/administration & dosage/*immunology/isolation & purification ; Humans ; Male ; Protective Agents/*administration & dosage/isolation & purification ; Sheep ; Vaccines/immunology