Development of a cell culture system to assess the effect of Cryptosporidium parvum infection on bystander cells

Abstract

Research has shown that the uninfected bystander cells in a C. parvum infected monolayer are at times preferentially apoptotic when compared to infected cells, and our goal was to further elucidate this effect in a nontumorgenic porcine intestinal cell line, IPEC‐J2. The effect of infective dose and duration of infection on the monolayer were assessed by determining the number of organisms, each life stage of C. parvum, total IPEC cells, infected cells, organisms per infected cell, total apoptotic cells, and infected, apoptotic cells. Coculture of infected monolayers with uninfected monolayers was used to assess the bystander effect on transepithelial electrical resistance and cell fate.The percentage of IPEC cells that became infected was similar with each dose, ranging from 37‐41% and peaked at 48 hours with the higher doses leading to multiple organisms per infected cell. All doses similarly decreased the total number of cells per high power field with no difference in the effect on bystander cells. During the first 24 hours, bystander cells appeared to be preferentially lost and accounted for the decrease in total cell numbers with significantly more apoptotic, bystander cells than apoptotic, infected cells per field. Early in C. parvum infections, bystander cells appear to play a significant role in the pathophysiology of disease.