Recombinant and native TviCATL from Trypanosoma vivax: Enzymatic characterisation and evaluation as a diagnostic target for animal African trypanosomosis.

Abstract

African animal trypanosomosis (nagana) is caused by tsetse-transmitted protozoan parasites. Their cysteine proteases are potential chemotherapeutic and diagnostic targets. The N-glycosylated catalytic domain of Trypanosoma vivax cathepsin L-like cysteine protease, rTviCATL, was recombinantly expressed and purified from culture supernatants while native TviCATL was purified from T. vivax Y486 parasite lysates. Typical of Clan CA, family Cproteases, TviCATL activity is sensitive to E-64 and cystatin and substrate specificity is defined by the Spocket. Leucine was preferred in Pand basic and non-bulky, hydrophobic residues accepted in Pand Prespectively. Reversible aldehyde inhibitors, antipain, chymostatin and leupeptin, with Arg in Pand irreversible peptidyl chloromethylketone inhibitors with hydrophobic residues in Pinhibited TviCATL activity. TviCATL digested host proteins: bovine haemoglobin, serum albumin, fibrinogen and denatured collagen (gelatine) over a wide pH range, including neutral to slightly acidic pH. The recombinant catalytic domain of TviCATL showed promise as a diagnostic target for detecting T. vivax infection in cattle in an indirect antibody detection ELISA.