Nav: Home

'Hijacking' and hibernating parasite could alter brain behavior

December 09, 2015

Melbourne researchers have discovered how a common parasite hijacks host cells and stockpiles food so it can lie dormant for decades, possibly changing its host's behaviour or personality in the process.

The findings could lead to a vaccine to protect pregnant women from Toxoplasma infection, which carries a serious risk of miscarriage or birth defects, as well as drugs to clear chronic infections in people with compromised immune systems, such as cancer patients.

Toxoplasma is a common parasite transmitted by cats and found in raw meat. Around 30 per cent of the population is infected. The research projects were led by Dr Chris Tonkin, Dr Justin Boddey, Dr Alex Uboldi, Mr James McCoy and Mr Michael Coffey from the Walter and Eliza Hall Institute.

Dr Tonkin said Toxoplasma required a human host cell - such as a brain cell (neuron) - to live in. The research team discovered how the parasite hijacks the host cell to enable its own growth and survival, hibernating for decades by creating its own food reserve.

"Toxoplasma infection leads to massive changes in the host cell to prevent immune attack and enable it to acquire a steady nutrient supply," Dr Tonkin said. "The parasite achieves this by sending proteins into the host cell that manipulate the host's own cellular pathways, enabling it to grow and reproduce."

Dr Boddey said some of these proteins might even influence the behaviour of the host. "There is a fascinating association between Toxoplasma infection and psychiatric diseases including schizophrenia and bipolar disorder. It is now possible to test whether proteins sent from the hibernating parasite into a host neuron disrupt normal brain function and contribute to development of these diseases," he said.

Once Toxoplasma parasites establish infection, they can lie dormant in our bodies for the rest of our lives. In people with suppressed immune systems, such as cancer patients, the parasite can reactivate and cause neurological damage and even death.

Dr Tonkin said the teams had identified pathways that allow the parasite to establish chronic infections, unveiling potential avenues for treatment that clear the dormant parasite.

"We discovered that, similar to animals preparing for hibernation, Toxoplasma parasites stockpile large amounts of starch when they become dormant," he said. "By identifying and disabling the switch that drives starch storage, we found that we could kill the dormant parasites, preventing them from establishing a chronic infection."

Dr Tonkin said the finding could lead to a drug to clear chronic Toxoplasma infections, or even a vaccine to prevent infection in at-risk people, such as pregnant women.

"Cats are one of the primary transmitters of Toxoplasma parasites," Dr Tonkin said. "If the parasites are transmitted to pregnant women, for example through contact with kitty litter, there is a substantial risk of miscarriage or birth defects.

"We hope to use our discoveries to develop a vaccine that stops cats transmitting the parasite, to prevent these potentially catastrophic consequences."

Dr Boddey said it had long been a mystery how the Toxoplasma parasite transported proteins into the host. "Our study showed that the parasite includes a signature on the exported proteins that 'earmark' them for transport into the host cell," he said. "Blocking transport makes the parasite much less dangerous in infection models, suggesting this may also be a new way of treating Toxoplasma infections."
-end-
The research findings were published today in the journal Cell Host & Microbe and in the journal eLife. They were supported by the National Health and Medical Research Council, the Australian Research Council, veski, the Human Frontiers Science Program and the Victorian State Government Operational Infrastructure Support Program.

Walter and Eliza Hall Institute

Related Parasites Articles:

Study shows interactions between bacteria and parasites
A team at the Technical University of Munich (TUM) has completed the first study of the effects of a simultaneous infection with blood flukes (schistosomes) and the bacterium Helicobacter pylori -- a fairly common occurrence in some parts of the world.
Evolution designed by parasites
In 'Invisible Designers: Brain Evolution Through the Lens of Parasite Manipulation,' published in the September 2019 issue of The Quarterly Review of Biology, Marco Del Giudice explores an overlooked aspect of the relationship between parasites and their hosts by systematically discussing the ways in which parasitic behavior manipulation may encourage the evolution of mechanisms in the host's nervous and endocrine systems.
Smuggling route for cells protects DNA from parasites
An international research team has now uncovered new insight into how safety mechanisms keep genetic parasites in check so that they do not damage the genome.
Airless worms: A new hope against drug-resistant parasites
Toronto scientists have uncovered a metabolic pathway that only exists in parasitic worms.
Parasites dampen beetle's fight or flight response
Beetles infected with parasitic worms put up less of a fight against simulated attacks from predators and rival males, according to a study by Felicia Ebot-Ojong, Andrew Davis and Elizabeth Jurado at the University of Georgia, USA, publishing May 22, 2019 in the open-access journal PLOS ONE.
Genome structure of malaria parasites linked to virulence
An international research team led by scientists at the University of California, Riverside, and the La Jolla Institute for Immunology has found that malaria parasite genomes are shaped by parasite-specific gene families, and that this genome organization strongly correlates with the parasite's virulence.
Parasites discovered in fossil fly pupae
Parasitic wasps existed as early as several million years ago.
Migratory animals carry more parasites, says study
Every year, billions of animals migrate across the globe, carrying parasites with them and encountering parasites through their travels.
The macabre world of mind-controlling parasites
Many parasites can control the behavior of their hosts -- sometimes in very gruesome ways.
Long incubation times may defend birds against parasites
Some tropical birds have longer egg incubation times than their temperate cousins, even though their habitat is teeming with egg-eating predators.
More Parasites News and Parasites Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.