Figure 1. Detection of Entamoeba histolytica cysts in Percoll purified cyst samples by immunofluorescence to the Jacob protein.

E. histolytica cysts were purified using the Percoll density gradient centrifugation [26]–[28], and about 50 µL of the purified cysts were fixed in microscopic slides by adding 4% formaldehyde solution for 1 hour at 37°C. After washing with 1× PBS containing 0.1% Triton X-100, cells were treated with either 1∶200 diluted post-immune or pre-immune antisera against E. histolytica cyst-wall specific Jacob protein raised in rabbits. They were then labeled with 1∶200 diluted FITC-conjugated goat anti-rabbit secondary antibody and examined by immunofluorescence microscopy. (a) Anti-Jacob antisera stained the cyst wall (shown by white arrows), (b) while pre-immune antisera failed to stain cyst wall. White bar is approximately 10 microns.