Novel insights into the potential role of ion transport in sensory perception in Acanthamoeba

Background
Acanthamoeba is well known to produce a blinding keratitis and serious brain infection known as encephalitis. Effective treatment is problematic, and can continue up to a year, and even then, recurrence can ensue. Partly, this is due to the capability of vegetative amoebae to convert into resistant cysts. Cysts can persist in an inactive form for decades while retaining their pathogenicity. It is not clear how Acanthamoeba cysts monitor environmental changes, and determine favourable conditions leading to their emergence as viable trophozoites.

Methods
The role of ion transporters in the encystation and excystation of Acanthamoeba remains unclear. Here, we investigated the role of sodium, potassium and calcium ion transporters as well as proton pump inhibitors on A. castellanii encystation and excystation and their effects on trophozoites.

Results
Remarkably 3′,4′-dichlorobenzamil hydrochloride a sodium–calcium exchange inhibitor, completely abolished excystation of Acanthamoeba. Furthermore, lanthanum oxide and stevioside hydrate, both potassium transport inhibitors, resulted in the partial inhibition of Acanthamoeba excystation. Conversely, none of the ion transport inhibitors affected encystation or had any effects on Acanthamoeba trophozoites viability.

Conclusions
The present study indicates that ion transporters are involved in sensory perception of A. castellanii suggesting their value as potential therapeutic targets to block cellular differentiation that presents a significant challenge in the successful prognosis of Acanthamoeba infections.