Fig. 6

Biological activity of Ac-cathB-2 in the host intestinal penetration of L3. a Digestion of Z-RR-AMC by rAc-cathB-2 and inhibition of proteolytic digestion by antiserum to Ac-cathB-2 was assessed. The activated rAc-cathB-2 was incubated with PBS, antiserum against Ac-cathB-2 (positive serum), normal mice serum (negative serum) and 20 μM E64. b Effects of positive serum and gastric acid on larval gut penetration were assessed. Two hundred of activated L3 and normal L3 were respectively incubated with the positive serum, the negative serum, PBS and E64 for 30 min. After incubation, the ability of gut penetration for L3 was determined by counting the number of larvae remaining in the gut lumen, and the data were presented as the penetration rate. Asterisk indicates P < 0.05; ns, not significant