title: Molecular characterization of cathepsin B from Clonorchis sinensis excretory/secretory products and assessment of its potential for serodiagnosis of clonorchiasis.
abstract: BACKGROUND
  Cathepsin cysteine proteases play multiple roles in the life cycle of parasites such as food uptake, immune invasion and pathogenesis, making them valuable targets for diagnostic assays, vaccines and drugs. The purpose of this study was to identify a cathepsin B of Clonorchis sinensis (CsCB) and to investigate its diagnostic value for human helminthiases.
  
  
  RESULTS
  The predicted amino acid sequence of the cathepsin B of C. sinensis shared 63%, 52%, 50% identity with that of Schistosoma japonicum, Homo sapiens and Fasciola hepatica, respectively. Sequence encoding proenzyme of CsCB was overexpressed in Escherichia coli. Reverse transcription PCR experiments revealed that CsCB transcribed in both adult worm and metacercaria of C. sinensis. CsCB was identified as a C. sinensis excretory/secretory product by immunoblot assay, which was consistent with immunohistochemical localization showing that CsCB was especially expressed in the intestine of C. sinensis adults. Both ELISA and western blotting analysis showed recombinant CsCB could react with human sera from clonorchiasis and other helminthiases.
  
  
  CONCLUSIONS
  Our findings revealed that secreted CsCB may play an important role in the biology of C. sinensis and could be a diagnostic candidate for helminthiases.
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, People's Republic of China.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Chen
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Wang
authors.forename: Xuerong
authors.initials: X
authors.lastname: Li
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Lv
authors.forename: Chenhui
authors.initials: C
authors.lastname: Zhou
authors.forename: Chuanhuan
authors.initials: C
authors.lastname: Deng
authors.forename: Huali
authors.initials: H
authors.lastname: Lei
authors.forename: Jingtao
authors.initials: J
authors.lastname: Men
authors.forename: Yongxiu
authors.initials: Y
authors.lastname: Fan
authors.forename: Chi
authors.initials: C
authors.lastname: Liang
authors.forename: Xinbing
authors.initials: X
authors.lastname: Yu
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D015153:Blotting, Western; D002401:Cathepsin B / Q000235:genetics* / Q000378:metabolism*; D019411:Clinical Laboratory Techniques / Q000379:methods*; D003001:Cloning, Molecular; D003003:Clonorchiasis / Q000175:diagnosis*; D003004:Clonorchis sinensis / Q000201:enzymology* / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000235:genetics; D005210:Fasciola hepatica / Q000235:genetics; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D058488:Metacercariae / Q000201:enzymology / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012549:Schistosoma japonicum / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012698:Serologic Tests / Q000379:methods
chemical_list: D000909:Antibodies, Helminth; D002401:Cathepsin B