FIG. 6.

Secreted products and soluble components contain a heat-labile protease that is partly responsible for neuron damage in enteric cocultures. (A) The damaging effect of E. histolytica factors was abrogated by boiling (n = 4) or prior treatment with the protease inhibitor E64 (10 μM; n = 5) prior to addition to the cocultures. *, P < 0.05 versus untreated control. (B) Secreted or soluble factors from a CP5^−/− E. histolytica (CP5) caused similar neuronal toxicity as wild-type vector products in enteric cocultures by 48 h posttreatment with Eh-SEC cp5 or Eh-SOL cp5 (30 μg/ml; n = 5). *, P < 0.05 relative to control.