For the first time, malaria 'caught in the act'

An international team, led by Walter and Eliza Hall Institute, has used new image and cell technologies to obtain the images of how malaria parasites attack red blood cells, the 'Cell Host & Microbe' journal reported.

Lead scientist Dr Jake Baum said the real breakthrough for the team had been the ability to capture high-resolution images of the parasite at each and every stage of invasion, and to do so reliably and repeatedly.

"It is the first time we've been able to actually visualise this process in all its molecular glory, combining new advances developed at the institute for isolating viable parasites with innovative imaging technologies.

"Super resolution microscopy has opened up a new realm of understanding into how malaria parasites actually invade the human red blood cell.

"Whilst we have observed this miniature parasite drive its way into the cell before, the beauty of the new imaging technology is that it provides a quantum leap in the amount of detail we can see, revealing key molecular and cellular events required for each stage of the
invasion process," Baum said.

The imaging technology, called OMX 3D SIM super resolution microscopy, is a powerful new 3D tool that captures cellular processes unfolding at nanometre scales.

"This is just the beginning of an exciting new era of discoveries enabled by this technology that will lead to a better understanding of how microbes such as malaria, bacteria and viruses cause infectious disease," team member Professor Cynthia Whitchurch said.

The scientists said the methodology would be integral to the development of new malaria drugs and vaccines.

"If, for example, you wanted to test a particular drug or vaccine, or investigate how a particular human antibody works to protect you from malaria, this imaging approach now gives us a window to see the actual effects that each reagent or antibody has on the precise steps of invasion," Baum said.

Malaria is caused by the Plasmodium parasite, which is transmitted by the bite of infected mosquitoes. Each year more than 400 million people worldwide contract malaria and as many as a million, mostly children, die.

"Historically it has been very difficult to both isolate live and viable parasites for infection of red blood cells and to employ imaging technologies sensitive enough to capture snapshots of the invasion process with these parasites, which are only one micron in diameter," Baum said.

He said one of the most interesting discoveries the imaging approach revealed was that once the parasite has attached to the red blood cell and formed a tight bond with the cell, a master switch for invasion is initiated and invasion will continue unabated without further checkpoints.

"This technology enables us to look at individual proteins that we always knew were involved in invasion, but we never knew what they did or where they were, and that, we believe, is a real leap for malaria researchers worldwide," he said.