The findings are a key step in getting closer to a vaccine to protect pregnant women from the parasiteToxoplasma gondii, miscarri的严重风险age or birth defects. The parasite is common in Australia, being carried by 30 per cent of the Australian population, and is transmitted by cat faeces and can also be acquired from raw meat.Toxoplasmainfection may also have a link to neurological disorders such as schizophrenia.

The research, published today in the journalPLOS Biology, was led by Associate Professor Chris Tonkin, Dr Alex Uboldi and Ms Mary-Louise Wilde from the Walter and Eliza Hall Institute.

At a glance

• The parasiteToxoplasma gondiiis carried by 30 per cent of the Australian population, and is a significant cause of miscarriage and birth defects.
• Walter and Eliza Hall Institute researchers have discovered that a factor called protein kinase A (PKA) is required forToxoplasma gondiito invade a host cell.
• The finding could lead to a vaccine or treatment for Toxoplasmosis, and sheds light on more general processes involved in other diseases caused by related parasites such as malaria.
• The breakthrough was possible through use of high-quality imaging facilities at the Institute's Centre for Dynamic Imaging.

Cut the brakes

There are two important steps allowingToxoplasma gondiito take hold within our body: the parasite needs to enter a host cell, and from there it replicates and spreads.

"AfterToxoplasmainfects humans it needs to switch off the infection machinery and switch on replication," Associate Professor Tonkin said. 'Without the ability to do this,Toxoplasmawill die and be unable to cause disease. We discovered that the gene protein kinase A (PKA) is required for this switch. Without PKA,Toxoplasmacan't hold steady."

Importance of new technology

According to Dr Uboldi, the discovery was made using advanced microscopy technology available at the Institute's Centre for Dynamic Imaging.

"It wasn't until we observed the parasite down the microscope and studied its behaviour that we noticed something unexpected," Dr Uboldi said.

"This was fully dependent on our access to the sophisticated equipment at the Institute's Centre for Dynamic Imaging.

"By actually watching the process take place in real time, we had that rare Eureka moment."

Wide-ranging implications

Ms Wilde, a PhD student at the Institute, noted thatToxoplasma gondiiis closely related to parasites that cause a range of globally significant diseases, such as malaria.

"Central to all these parasites is that they need to invade host cells in order to survive," Ms Wilde said.

"Understanding the role that PKA plays in theToxoplasmalifecycle could provide insights into the biology of other disease-causing parasites, such as Plasmodium, which causes malaria.

"PKA belongs to a class of molecules that are a really important drug target for other diseases such as cancer and diabetes. We now might be able to take our understanding of how PKA functions in these diseases to design new therapies for toxoplasmosis and infections caused by related parasites," she said.

The research findings were supported by the National Health and Medical Research Council and an Australian Research Council fellowship.