JAN 29, 2018 2:29 PM PST

Parasitic Molecules Mimic Human Proteins & Chew Through the Gut

WRITTEN BY: Carmen Leitch

One of the most common gastric diseases in the world is due to a parasitic infection from Giardia parasites. New research has revealed how these pathogens cause gut distress; they appear to mimic human molecules, then break gut cells down and consume them as food. This solves a mystery that has eluded scientists for over 300 years. The findings, by investigators at the University of East Anglia, has been reported in GigaScience.

Giardia under the microscope. / Credit: Suha Al Naimi and Kevin Tyler

The Giardia parasite synthesizes two proteins that enable it to break through the layers of mucosal protection in the gut, cutting a barrier that maintains gastrointestinal health. The process allows the pathogen to get to the nutrients behind the gut barrier easily. 

Typically, the Giardia parasite gets into people through contaminated drinking water or food, causing the disease giardiasis. Rates may be as high as seven percent in high-income nations, and thirty percent in low-income countries.

The researchers were interested in knowing why the parasite causes very serious problems for some people. The team at the National Institute for Health Research Health Protection Research Unit in Gastrointestinal Infections of UEA's Norwich Medical School collaborated with colleagues from the Institute of Infection and Global Health at the University of Liverpool. They found that when giardia infected cells in culture, two protein families were made by the parasite. Further study indicated that one of those families can mimic human proteins called tenascins.

Tenascins are critical for tissue health under normal conditions. They control cell adhesion after wounds and direct tissue remodeling. They aid cells that must break apart, as well as regulating the proteins that hold cells together. The parasite appears to have evolved to make proteins that can behave similarly to human proteins, to interfere with these processes. 

The tenascins that giardia makes don’t hold cells together, however. Instead, they disrupt the junctions keeping cells together and prevent them from healing. 

"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' which can make giardiasis even more severe for some,” said the senior author of the work, Dr. Kevin Tyler of the Norwich Medical School at UEA.

"Giardia was one of the very first disease-causing microbes to be visualized - scientists have known of its existence since 1681. But this is the first time we have been able properly to understand why this parasite is so successful," he continued.

The team plans to pursue the research further; next, they want to see if these proteins can be neutralized as a therapeutic for the illness. They are wondering if differences in those molecules might indicate which strains are causing more severe illnesses, something not currently known. Learn more about giardiasis from the video.


Sources: AAAS/Eurekalert! via University of East Anglia, GigaScience

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
MAR 22, 2020
Microbiology
MAR 22, 2020
Men Are More Susceptible to COVID-19 Than Women
More data is being gathered from an unfortunate and dramatic rise in the number of COVID-19 cases around the world.
APR 13, 2020
Microbiology
APR 13, 2020
Even Bacteria Align With the Daily Cycle of Day and Night
The majority of living organisms on Earth have adapted in some way to the daily cycle of night and day.
APR 28, 2020
Microbiology
APR 28, 2020
Communities of Microbes Can Form 'Memories'
Microbes can grow in tight clusters called biofilms. These communities are tough, and have some of the same properties a ...
APR 29, 2020
Clinical & Molecular DX
APR 29, 2020
Saliva is Preferable to Deep Nasal Swabs for COVID-19 Testing
The coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Incre ...
APR 29, 2020
Microbiology
APR 29, 2020
Bacteria Exposed to Antibiotics are 'Primed' to Gain More Resistance
Antibiotics are critical drugs that have saved millions of lives, but bacteria can also gain resistance to them, renderi ...
MAY 12, 2020
Microbiology
MAY 12, 2020
Understanding How Giant Viruses Can Infect Cells
Melting permafrost has been revealing some remarkably well-preserved and extremely old stuff, like a prehistoric puppy a ...
Loading Comments...