Rice University researchers find new possibilities for benign, ‘tunable’ virus
Rice University scientists have designed a tunable virus that works like a safe deposit box. It takes two keys to open it and release its therapeutic cargo.
An adeno-associated virus capsid (blue) modified by peptides (red) inserted to lock the virus is the result of research at Rice University into a new way to target cancerous and other diseased cells. The peptides are keyed to proteases overexpressed at the site of diseased tissues; they unlock the capsid and allow it to deliver its therapeutic cargo. (Credit: Junghae Suh/Rice University)
The Rice lab of bioengineer Junghae Suh has developed an adeno-associated virus (AAV) that unlocks only in the presence of two selected proteases, enzymes that cut up other proteins for disposal. Because certain proteases are elevated at tumor sites, the viruses can be designed to target and destroy the cancer cells.
The work appears online this week in the American Chemical Society journal ACS Nano. AAVs are fairly benign and have become the object of intense study as delivery vehicles for gene therapies. Researchers often try to target AAVs to cellular receptors that may be slightly overexpressed on diseased cells. The Rice lab takes a different approach. “We were looking for other types of biomarkers beyond cellular receptors present at disease sites,” Suh said.
“In breast cancer, for example, it’s known the tumor cells oversecrete extracellular proteases, but perhaps more important are the infiltrating immune cells that migrate into the tumor microenvironment and start dumping out a whole bunch of proteases as well. “So that’s what we’re going after to do targeted delivery. Our basic idea is to create viruses that, in the locked configuration, can’t do anything. They’re inert,” she said.
When programmed AAVs encounter the right protease keys at sites of disease, “these viruses unlock, bind to the cells and deliver payloads that will either kill the cells for cancer therapy or deliver genes that can fix them for other disease applications.” Suh’s lab genetically inserts peptides into the self-assembling AAVs to lock the capsids, the hard shells that protect genes contained within.
The target proteases recognize the peptides “and chew off the locks,” effectively unlocking the virus and allowing it to bind to the diseased cells. “If we were just looking for one protease, it might be at the cancer site, but it could also be somewhere else in your body where you have inflammation. This could lead to undesirable side effects,” she said.
“By requiring two different proteases – let’s say protease A and protease B – to open the locked virus, we may achieve higher delivery specificity since the chance of having both proteases elevated at a site becomes smaller.” In the future, molecular-imaging approaches will be used to detect both the identity and concentration of elevated proteases.
“With that information, we would be able to pick a virus device from our panel of engineered variants that has the right properties to target that disease site. That’s where we want to go,” she said. Suh said elevated proteases are found around many diseased tissues. She suggested these protease-activatable viruses may be useful for the treatment of not only cancers but also neurological diseases, such as stroke, Parkinson’s and Alzheimer’s diseases, and heart diseases, including myocardial infarction and congestive heart failure. The ultimate vision of this technology is to design viruses that can carry out a combination of steps for targeting.
“To increase the specificity of virus unlocking, you can imagine creating viruses that require many more keys to open,” she said. “For example, you may need both proteases A and B as well as a cellular receptor to unlock the virus. The work reported here is a good first step toward this goal.”
Co-authors are Rice alumni Justin Judd and Abhinav Tiwari; graduate students Michelle Ho, Eric Gomez and Christopher Dempsey; Oleg Igoshin, an associate professor of bioengineering; and Jonathan Silberg, an associate professor of biochemistry and cell biology, all at Rice; and Kim Van Vliet, an assistant research scientist, and Mavis Agbandje-McKenna, a professor, both at the University of Florida. Suh is an assistant professor of bioengineering. The National Science Foundation, the National Institutes of Health, the American Heart Association and the Cancer Prevention and Research Institute of Texas supported the research.
David Ruth | Eurek Alert!
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences