Complete development and long-term maintenance of Cryptosporidium parvum human and cattle genotypes in cell culture.

This study describes the complete development (from sporozoites to sporulated oocysts) of Cryptosporidium parvum (human and cattle genotypes) in the HCT-8 cell line. Furthermore, for the first time the complete life cycle was perpetuated in vitro for up to 25 days by subculturing. The long-term maintenance of the developmental cycle of the parasite in vitro appeared to be due to the initiation of the auto-reinfection cycle of C. parvum. This auto-reinfection is characterised by the production and excystation of new invasive sporozoites from thin-walled oocysts, with subsequent maintenance of the complete life cycle in vitro. In addition, thin-walled oocysts of the cattle genotype were infective for ARC/Swiss mice but similar oocysts of the human genotype were not. This culture system will provide a model for propagation of the complete life cycle of C. parvum in vitro.