“…Indeed, both stages require gut-associated peptidases to digest host proteins. In T. regenti, isoforms of the cysteine peptidase cathepsin B1 (TrCB1) are expressed in the gut and represent a subset of a larger group of peptidases that are responsible for digestion (Dvořák et al, 2005;Dolečková et al, 2010;Leontovyč et al, 2016Leontovyč et al, , 2019, much like in human Schistosoma species (Caffrey et al, 2004) and other helminths (Williamson et al, 2003(Williamson et al, , 2004Delcroix et al, 2006;Caffrey et al, 2018). Cathepsin B (IUPAC: EC 3.4.22.1; MEROPS: Clan CA, Family C1) is unique among other papain-like cysteine peptidases due to its ability to act as both an endopeptidase and carboxy-exopeptidase (peptidyl dipeptidase) ( Barrett and Kirschke, 1981).…”