January 19, 2009 — Researchers provide insight
into how Toxoplasma gondii, a common parasite of people and other
animals, triggers an immune response in its host.
A strong immune response spares T. gondii-infected hosts from deadly
infection—an event that may also benefit the parasite, which relies on
survival of the host to ensure its own transmission. But how the
infected host elicits an immune response isn’t completely understood.
Like many other parasites, T. gondii resides within specialized
vesicles inside infected host cells, but the process by which peptides
from the trapped bugs are processed by infected cells and presented to
killer T cells is mysterious.
In new research, Romina Goldszmid and her colleagues at the National
Institutes of Health in Bethesda use T. gondii infections in mice to
study how portions of the parasitic proteins escape the vesicle in a
process known as cross-presentation.
They find that the parasite gets noticed by the immune system when
the membrane of the bug-containing vesicle fuses to the endoplasmic
reticulum—an organelle normally involved in presenting pathogens to T
cells—allowing a swap of parasitic peptides.
The report will appear online on January 19th in The Journal of Experimental Medicine.
Source : Rockefeller University Press