Parasitology

Research Article

Comparison of cysteine peptidase activities in Trichobilharzia regenti and Schistosoma mansoni cercariae

M. KAŠNÝa1 c1, L. MIKEŠa1, J. P. DALTONa2, A. P. MOUNTFORDa3 and P. HORÁKa1

a1 Charles University in Prague, Faculty of Science, Department of Parasitology, Viničná 7, 12844 Prague 2, Czech Republic

a2 Institute for the Biotechnology of Infectious Diseases, University of Technology Sydney, PO Box 123, Broadway, N.S.W. 2007 Sydney, Australia

a3 Department of Biology (Area 5), University of York, P.O. Box 373, York YO10 5YW, UK

SUMMARY

Cercariae of the bird schistosome Trichobilharzia regenti and of the human schistosome Schistosoma mansoni employ proteases to invade the skin of their definitive hosts. To investigate whether a similar proteolytic mechanism is used by both species, cercarial extracts of T. regenti and S. mansoni were biochemically characterized, with the primary focus on cysteine peptidases. A similar pattern of cysteine peptidase activities was detected by zymography of cercarial extracts and their chromatographic fractions from T. regenti and S. mansoni. The greatest peptidase activity was recorded in both species against the fluorogenic peptide substrate Z-Phe-Arg-AMC, commonly used to detect cathepsins B and L, and was markedly inhibited (>96%) by Z-Phe-Ala-CHN2 at pH 4·5. Cysteine peptidases of 33 kDa and 33–34 kDa were identified in extracts of T. regenti and S. mansoni cercariae employing a biotinylated Clan CA cysteine peptidase-specific inhibitor (DCG-04). Finally, cercarial extracts from both T. regenti and S. mansoni were able to degrade native substrates present in skin (collagen II and IV, keratin) at physiological pH suggesting that cysteine peptidases are important in the pentration of host skin.

(Received November 24 2006)

(Revised March 08 2006)

(Revised April 04 2007)

(Accepted April 04 2007)

(Online publication May 22 2007)

Correspondence:

c1 Corresponding author: Charles University in Prague, Faculty of Science, Department of Parasitology, Viničná 7, 12844 Prague 2, Czech Republic. Tel: +420 221 951 816. Fax: +420 224 919 704. E-mail: kasa@post.cz

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