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Associate Professor Theresa HT Coetzer
School of Molecular and Cellular Biosciences (Biochemistry)
University of KwaZulu-Natal
Pietermaritzburg, South Africa
Email: coetzer@nu.ac.za
Tel: +27 33 2605463
Fax: +27 33 2606127

We investigate proteases that are important factors in the development of African cattle trypanosomosis (nagana) as drug and vaccine targets. We have identified, purified and characterised a serine oligopeptidase, the opdB gene product, from Trypanosoma brucei brucei and T. congolense and a cysteine proteinase, trypanopain-Tb (brucipain) from T. b. brucei. We demonstrated that oligopeptidase B is a new member of the prolyl oligopeptidase family of serine hydrolases. We made a significant discovery that oligopeptidase B is released by disrupted parasites into the host circulation where it is unregulated and retains full catalytic activity and may thus play a role in the pathogenesis of trypanosomosis. A key tool for this study was the antibodies we produced in chickens (IgY) that selectively inhibited the activity of oligopeptidase B in plasma where coagulation and complement system peptidases have the same substrate specificity. We documented that oligopeptidase B is an intracellular target for several antitrypanosomal drugs currently in use, suggesting that serine protease inhibitors could represent a class of lead compounds for chemotherapeutic agent development. We consequently demonstrated that novel irreversible serine peptidase inhibitors have antitrypanosmal activity. We showed that trypanopain-Tb is essential for parasite viability in that several irreversible peptidyl-methylketone inhibitors, vinyl sulfones, chalcones and acyl hydrazides inhibited trypanopain-Tb activity and killed the parasites in culture, with potential for drug and vaccine targeting. We are currently identifying those epitopes in congopain and vivapain that produce anti-catalytic antibodies for inclusion in a vaccine and a field trial is underway. These proteases also have potential for trypanosomosis diagnosis.
Dr Edith Authiè, International Livestock Research Institute (ILRI), Nairobi, Kenya and CIRAD-EMVT, Montpellier, France
Prof. Theo Baltz, Laboratoire de Parasitologie moléculaire, Université Victor Segalen, Bordeaux, France
Dr Alain Boulange, ILRI, Nairobi, Kenya and CIRAD-EMVT, Montpellier, France
Dr Philippe Büscher, Institute of Tropical Medicine, Department of Parasitology, Antwerp, Belgium
Prof. Fred Cohen, Department of Pharmacology and Medicine, University of California, San Francisco, CA, USA
Dr Gilles Lalmanach, Laboratoire d’Enzymologie et de Chimie des proteins, University François Rabelais, Faculty of Medecine, Tours, France.
Prof. James H McKerrow, Departments of Pathology and Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
Dr Rory E Morty, Centre for Internal Medicine, Justus Liebig University, Giessen, Germany
Dr Jim Palmer, Axys Pharmaceuticals, San Francisco, CA, USA
Dr Rob Pike, Monash University, Melbourne, Australia
Dr James C Powers, Georgia Institute for Technology, Atlanta, USA
Morty, R.E., Lonsdale-Eccles, J. D., Mentele,R., Auerswald,E.A. and Coetzer, T.H.T (2001) Trypanosome-derived oligopeptidase B is released into the plasma of infected rodents, where it persists and retains full catalytic activity. Infect. Immun. 69, 2757-2761.

Morty, R.E., Troeberg, L., Powers, J. C., Ono, S., Lonsdale-Eccles, J. D. and Coetzer, T.H.T. (2000) Characterisation of the antitrypanosomal activity of peptidyl a-aminoalkyl phosphonate diphenyl esters. Biochem. Pharmacol. 60, 1497-1504.

Morty, R.E., Lonsdale-Eccles, J. D., Morehead, J. , Caler, E. V., Mentele, R., Auerswald, E.A.,. Coetzer, T.H.T , Andrews, N. W. and Burleigh, B. A. (1999) Oligopeptidase B from Trypanosoma brucei. A new member of an emerging subgroup of serine oligopeptidases. J. Biol. Chem. 274, 26149-26156.

Morty, R.E., Authié, E., Troeberg, L., Lonsdale-Eccles, J.D. and Coetzer, T.H.T. (1999) Purification and characterisation of a trypsin-like serine oligopeptidase from Trypanosoma congolense Mol. Biochem. Parasitol. 102, 145-155.

Troeberg, L., Morty, R.E., Pike, R.N., Lonsdale-Eccles, J.D., Palmer, J.T., McKerrow, J.H. and Coetzer, T.H.T. (1999) Cysteine proteinase inhibitors kill cultured bloodstream forms of Trypanosoma brucei brucei Exp. Parsitol. 91, 349-355.

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