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1 October 2005 CHARACTERIZATION OF EXCRETORY/SECRETORY ENDOPEPTIDASE AND METALLO-AMINOPEPTIDASES FROM TAENIA CRASSICEPS METACESTODES
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Abstract

Cysticercosis is caused by Taenia spp. metacestodes, which must survive in the host tissues to complete their life cycle. Their survival depends on their control of host immune responses. Because many parasites use proteases to modulate host responses, we examined culture media from Taenia crassiceps metacestodes for protease activity using peptide substrates. We identified prominent aminopeptidase activity at neutral pH, which was inhibited by chelating agents and partially inhibited by the aminopeptidase inhibitor, bestatin. Endopeptidase substrates were optimally cleaved at slightly acidic pH and endopeptidase activity was inhibited by cysteine protease inhibitors. Gel filtration FPLC and subsequent visualization by silver staining revealed a metallo-aminopeptidase of molecular weight 21 kDa and cysteine proteases of Mr 70 and 64 kDA. Recombinant IL-2 was digested when incubated with parasite culture supernatants, but not with control media. IL-2 degradation was completely inhibited by 1,10 phenanthroline and partially inhibited by bestatin, suggesting that a metallo-aminopeptidase was responsible. Incubation of human IgG with culture supernatants resulted in complete degradation of IgG, which was blocked by cysteine protease inhibitors. These observations demonstrate that Taenia spp. metacestodes secrete a number of proteolytic enzymes, which may target molecules from the host immune system and assist in evasion of the host immune response.

Salman Baig, Raymond T. Damian, Jorge Morales-Montor, Paula Olecki, Jamil Talhouk, Rayhan Hashmey, and A. Clinton White Jr. "CHARACTERIZATION OF EXCRETORY/SECRETORY ENDOPEPTIDASE AND METALLO-AMINOPEPTIDASES FROM TAENIA CRASSICEPS METACESTODES," Journal of Parasitology 91(5), (1 October 2005). https://doi.org/10.1645/GE-200R1.1
Received: 29 July 2005; Accepted: 1 January 2005; Published: 1 October 2005
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