Using quantitative proteomic analysis, University of East Anglia researchers demonstrated that Giardia parasites are able to mimic human cell functions to break apart cells in the gut and feed off them. According to the team, the secret behind the success of giardia has eluded scientists trying to understand giardiasis for hundreds of years.
Specifically the team found that the parasite produces two main types of protein that enable it to cut through layers of protective mucus in the gut, breaking the links that knit cells together in order to easily access the nutrients within them.
Working with colleagues at the Institute of Infection and Global Health at the University of Liverpool, the team looked at cell cultures infected with giardia in the laboratory to see what the parasite was producing that could be interacting with cells in the gut. Of the two families of protein identified, the team discovered that one mimics a group of human proteins called Tenascins, which regulate cell adhesion during wound healing and tissue remodeling.
The giardia parasite has evolved by making proteins that are very similar to ours and able to trigger this process. However, the giardia tenascins are used instead to upset the body's balance by preventing healing of the junctions between cells that hold them together.
"We've discovered an entirely new model for how this disease develops in the gut, which can also explain why in some people the symptoms can be more severe. Because the giardia have broken down the cell barriers and made all these nutrients available, other, opportunistic bacteria can move in to take advantage of these 'ready meals' that can make giardiasis even more severe for some, senior author Kevin Tyler, from UEA's Norwich Medical School, explained.
The next step for the team is to look at whether neutralizing these proteins can provide therapy for the illness and to ask whether differences in these molecules, between parasites that cause more severe disease and those that do not, can be used to identify the more dangerous.
The research was published today in GigaScience.
Image: Giardia under the microscope. Image courtesy of Suha Al Naimi and Kevin Tyler.