Plant-like protein underpins common parasites' ability to infect

Researchers at Washington University School of Medicine have revealed that Toxoplasma gondii, a common human parasite, uses a plant-like protein for signalling when to increase its numbers and when to be dormant.

T. gondii is found in one in every four humans causing serious disease in patients with weakened immune systems.

However, in rare cases infection in healthy patients may lead to serious eye or central nervous system disease, or congenital defects in the foetuses of pregnant women.

The researchers were able to block the production of the molecule, known as abscisic acid (ABA), with the plant herbicide.

"As a target for drug development, this pathway is very attractive for several reasons," Nature quoted L. David Sibley lead author and professor of molecular microbiology.

"For example, because of its many roles in plant biology, we already have several inhibitors for it. Also, the plant-like nature of the target decreases the chances that blocking it with a drug will have significant negative side effects in human patients," he added.

T. gondii and those responsible for malaria include many plant-like pathways, or groups of genes or proteins put to work for a specific biological task.

ABA plays a vital role in regulating flowering and seed dormancy.

A string of experiments by Nagamune, assistant professor at Tsukuba University in Japan revealed that ABA helped the parasites to control their reproductive cycle by communicating with each other in the host cell.

When the parasites sensed high levels of ABA, they come out of host cells, else stay in it and remain dormant.

"Signals are sometimes even better targets for drug development than biosynthetic pathways," said Sibley. ...

•	Plant-like protein underpins common parasites' ability to infect DailyIndia.com (FL), Thursday, Jan. 10, 2008 Byline: ANI Correspondent

	Story also ran in 7 others:  Nature, Asian News International, Thaindian.com (Thailand), Medical News Today (UK), Biology News Net (Canada), PhysOrg.com (VA) and Newswise