Now Hugo Luján, a Howard Hughes Medical Institute international research scholar, reports that Giardia's extensive wardrobe of surface proteins might actually be its own downfall.
In an advance online publication in the journal Nature Medicine on April 25, 2010, Luján shows that Giardia parasites engineered to express all their surface proteins worked as vaccines that could help prevent or mitigate future infections. The same "overdressed" parasites offer protection when given orally to gerbils infected with Giardia, he says, though the idea still needs to be tested in humans.
Luján believes Giardia's hardy surface proteins—which help the parasite thrive in the harsh, acidic environments of the stomach and upper intestine—might eventually be used to deliver vaccines not just against Giardia but other parasites too, including malaria. "They could allow us to save money and lives," he says. "These proteins help the parasite survive but we're planning to use that armor to make new, oral vaccines."
A professor at the Catholic University of Córdoba, in Argentina, Luján's fascination with Giardia dates back to his days as a postdoctoral fellow in parasitology, working with Theodore Nash at the National Institutes of Health. Luján remembers being intrigued by Giardia's simplicity. Confining the parasite to a culture tube had no effect on its lifecycle, which made it easy to study and manipulate the organism. Upon returning to Argentina, Luján continued his research on Giardia, and in 2008, he reported that the shifty organism changes its appearance between 200 different protein coats using a molecular process called RNA interference (RNAi). As proof that RNAi was critical to the bug's "invisibility," he disabled its RNAi mechanism, and found that all the surface proteins appeared at once.
Luján reasoned that this genetically-altered parasite might make an optimal vaccine. Ordinarily, children in developing countries suffer the most from routine Giardia infections, which they usually get from drinking contaminated water. Adults rarely get as sick because they have built up immunity from earlier contact with the parasite. Luján's hypothesis was that a child exposed to all Giardia's surface proteins at once would be primed to resist any future infection.
Luján's team tested out the hypothesis on gerbils, which are a good model for scientists because they can be infected with the same Giardia parasites that attack humans. Those exposed to parasites expressing just one surface protein were re-infected easily by parasites expressing a different surface protein. But gerbils that had been exposed to a strain of Giardia that expressed all 200 surface proteins were less likely to be reinfected. Another welcome surprise was that the isolated proteins were non-toxic and elicited an immune response. According to Luján, this is the first time researchers have generated a vaccine purely from proteins, which can be stored at room temperature and delivered orally, both necessities for a vaccine that can be easily delivered in the developing world.
Luján plans to leverage the proteins' resistance to gastrointestinal enzymes by testing whether they can ferry other oral vaccinations into the body. In many cases, the surface proteins expressed by infectious pathogens are destroyed in the gastrointestinal tract before the immune system has a chance to respond. That's in part why oral vaccines for illnesses like malaria haven't been practical. But if attached to surface proteins from Giardia, Luján says, these antigens might survive in the gastrointestinal tract long enough to be recognized by the immune system.
"This could be a huge development," says Luján, who recently filed a patent application on his research with the U.S. Patent and Trademark Office. "Hopefully, we'll be able to use this system to make vaccinations that we can give in a very convenient way. Giardia's surface proteins are fascinating, and now we're finding that we can exploit what the parasite uses to defend itself to our own favor."
Andrea Widener | EurekAlert!
Study shines light on brain cells that coordinate movement
26.06.2017 | University of Washington Health Sciences/UW Medicine
New insight into a central biological dogma on ion transport
26.06.2017 | Aarhus University
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
26.06.2017 | Life Sciences
26.06.2017 | Physics and Astronomy
26.06.2017 | Information Technology