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Proteinases released in vitro by the parasitic stages of the bovine abomasal nematode Ostertagia ostertagi

Published online by Cambridge University Press:  27 April 2001

P. GELDHOF
Affiliation:
Department of Parasitology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B9820 Merelbeke, Belgium
E. CLAEREBOUT
Affiliation:
Department of Parasitology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B9820 Merelbeke, Belgium
D.P. KNOX
Affiliation:
Moredun Research Institute, Pentlands Science Park, Penicuik, Bush Loan, Midlothian, UK
J. AGNEESSENS
Affiliation:
Department of Parasitology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B9820 Merelbeke, Belgium
J. VERCRUYSSE
Affiliation:
Department of Parasitology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B9820 Merelbeke, Belgium

Abstract

Host tissue penetration, feeding and immune evasion by helminth parasites may be mediated by both mechanical processes and histolytic products released by the parasite. The aim of this study was to investigate potential histolytic products released during in vitro maintenance of exsheathed third (L3) and 4th larval stage (L4) and adult Ostertagia ostertagi. Therefore, the pH optima, substrate specificity, molecular size and inhibitor sensitivity of in vitro released (IVR) proteinases were analysed by spectrophotometry and substrate gel electrophoresis. It was shown that L3, L4 and adult IVR proteinases degrade a variety of protein substrates in a pH-dependent and stage-specific manner. At alkaline pH, gelatin, casein and fibrinogen were degraded by metallo- and serine proteinases. In contrast, mucin, fibrinogen, albumin and haemoglobin were degraded at acidic pH by aspartyl protease- and cathepsin L-like activity. At pH 3, the heavy chain of bovine IgG was completely degraded by an aspartyl proteinase secreted by all 3 parasitic stages. The specificity of the L3, L4 and adult Ostertagia ostertagi proteinases against the different substrates indicates variable functional requirements.

Type
Research Article
Copyright
2000 Cambridge University Press

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