<i>Giardia duodenalis</i> trophozoites do not induce catB/L activity within Caco-2 monolayers.

<p>This figure illustrates cathepsin activity within Caco-2 cells post co-incubation with trophozoites. <i>G</i>. <i>duodenalis</i> trophozoites (isolates NF, S2, or GS/M) were co-incubated with Caco-2 monolayers for 24 hours. Caco-2 cell lysates were collected and analyzed for cathepsin cysteine protease activity (A to C). As a representative figure, Caco-2 lysates co-incubated with <i>G</i>. <i>duodenalis</i> NF trophozoites were incubated with the catB/L fluorogenic substrate ZFR-AMC (200 μM: 5 min: 37°C: pH 7.2). Proteolytic activity is represented as the change in RFUs over time (A). Caco-2 lysates were collected and incubated with the catB/L fluorogenic substrate ZFR-AMC (B) or the catB-specific fluorogenic substrate (C) (ZRR-AMC) (200 μM: 5 min: 37°C: pH 7.2). Proteolytic activity was calculated by determining the change or slope in RFUs over time. Data are mean+/-SEM, n = 3.