Researchers Find Amoebas That Nibble Human Cells to Death

Posted on April 28, 2014

Entamoeba histolytica nibbling at human cells

Researchers at the University of Virginia School of Medicine have found amoebas that nibble at human cells. Until now, researchers had assumed that the amoeba, Entamoeba histolytica, killed and then engulfed and consumed human cells. The new finding shows that amoeba take small bites of human cells until the cells die. The amoeba than loses interest in eating the dead cell and moves onto other living cells. The image above shows Entamoeba histolytica parasites (green) ingesting bites of human Jurkat T cells (pink). The image was captured using live confocal video microscopy.

U.Va. researcher Katherine S. Ralston says in a statement, "This is the first demonstration that nibbling can serve as a way to kill other cells. The findings suggest that amoebae might invade and destroy host intestinal tissue by nibbling alive the cells that line the gut. Intriguingly, there are hints that organisms can also nibble. Perhaps this process is more common than we realize, and it is taken to the extreme in the case of the amoebae, which use nibbling to kill."

Entamoeba histolytica is an amoeba that causes a potentially fatal diarrhea in the developing world. Approximately a third of all infants are infected within their first year of life in the Bangladeshi slum where the U.Va. researchers have been working. The amoebae colonize the colon and begin nibbling at cells. This can produce diarrhea, inflammation of the colon, bowel diseases � or sometimes even no symptoms at all.

Dr. William A. Petri Jr., chief of U.Va.'s Division of Infectious Diseases and International Health, says in a statement, "It has been 111 years exactly since this parasite was named 'histolytica' for its ability to lyse tissues. Finally, the way it kills has been discovered. This provides an avenue to explore how best to prevent and treat this parasite that infects up to one of every three children by their first birthday in Bangladesh."

Ralston told Science Now the discovery could potentially lead to the new treatments. She says, "If we could understand how the amoeba takes a bite, that would be a good target for therapeutic drugs."

The research was published here in the journal Nature.

Photo: Katherine Ralston