Bile acids enhance invasiveness of Cryptosporidium spp. into cultured cells.

Bile salts such as sodium taurocholate (NaTC) are routinely used to induce the excystation of Cryptosporidium oocysts. Here we show that NaTC significantly enhanced the invasion of several cultured cell lines by freshly excysted Cryptosporidium parvum and Cryptosporidium hominis sporozoites. A variety of purified bile salts or total bile from bovine also enhanced the invasion of cultured cells by C. parvum. Further studies demonstrated that NaTC increased protein secretion and gliding motility of sporozoites, the key processes for successful invasion. These observations may lead to improved Cryptosporidium infectivity of cultured cells and help future studies on the host-parasite interaction.