Complete development of Cryptosporidium parvum in a human endometrial carcinoma cell line

Sporozoites of Cryptosporidium parvum, excysted from oocysts isolated from calves, were applied to monolayers of the human endometrial carcinoma cell line RL95-2. Cells were grown as monolayers in 24-well plates at concentrations ranging from 5 x 10(4) to 1 x 10(5) RL95-2 cells per well. At 1 or 7 days postculturing, C. parvum sporozoites (ranging from 1 x 10(5) to 2 x 10(5) were added to the monolayers of RL95-2 cells. The cells were fixed and stained to estimate the extent of parasite colonization. Light microscopy and electron microscopy confirmed the development and replication of C. parvum within the RL95-2 cells. A standardized and reproducible in vitro culture system for C. parvum is necessary to evaluate therapies against cryptosporidiosis.