Entamoeba histolytica is a human intestinal parasite that causes amoebic dysentery (a diarrheal disease). Since E. histolytica is a food- and water-borne pathogen with a high potential for mass dissemination, the NIH has classified it as a Category B priority bioterrorism agent. The disease can be contracted by ingestion of contaminated food or water that contains E. histolytica spores. Once in the human intestine, this parasite becomes highly motile and invades the wall of the intestine, causing tissue destruction and bloody diarrhea. The invasiveness of E. histolytica depends on its ability to engulf human red blood cells, bacteria, and other contents of human large intestines. The process of engulfing large particles, such as human cells, bacteria, or fungi is called phagocytosis. It is important to understand the biology of phagocytosis in this parasite in order to develop means of preventing and treating dysentery. This scanning electron micrograph shows phagocytosis of a fungus by E. histolytica. The micrograph was false colored in Adobe Photoshop. E. histolytica is indicated in pink, while the fungus it is engulfing is shown in yellow. You can observe membrane ruffling at the point of entry of the fungus. Dormant amoeba can be seen in the background shown in blue. This is the first electron micrograph capturing the uptake of fungi by E. histolytica.
The work was supported by a grant from the NIH (NIAID AI046414) to Dr. Lesly Temesvari.