Featured Research

from universities, journals, and other organizations

First measurement of energy released from a virus during infection

Date:
February 7, 2010
Source:
Carnegie Mellon University
Summary:
For the first time, scientists have directly measured the energy associated with the expulsion of viral DNA, a pivotal discovery toward fully understanding the physical mechanisms that control viral infection and designing drugs to interfere with the process.

3D reconstruction of bacteriophage lambda with (left) and without (right) DNA.
Credit: Image courtesy of Carnegie Mellon University

Within a virus's tiny exterior is a store of energy waiting to be unleashed. When the virus encounters a host cell, this pent-up energy is released, propelling the viral DNA into the cell and turning it into a virus factory. For the first time, Carnegie Mellon University physicist Alex Evilevitch has directly measured the energy associated with the expulsion of viral DNA, a pivotal discovery toward fully understanding the physical mechanisms that control viral infection and designing drugs to interfere with the process.

"We are studying the physics of viruses, not the biology of viruses," said Evilevitch, associate professor of physics in the Mellon College of Science at Carnegie Mellon. "By treating viruses as physical objects, we can identify physical properties and mechanisms of infection that are common to a variety of viruses, regardless of their biological makeup, which could lead to the development of broad spectrum antiviral drugs."

Current antiviral medications are highly specialized. They target molecules essential to the replication cycle of specific viruses, such as HIV or influenza, limiting the drugs' use to specific diseases. Additionally, viruses mutate over time and may become less susceptible to the medication. Evilevitch's work in the burgeoning field of physical virology stands to provide tools for the rational design of less-specialized antiviral drugs that will have the ability to treat a broad range of viruses by interrupting the release of viral genomes into cells.

Evilevitch's current findings also have the potential to improve the development of gene therapy, which uses viruses to deliver functional genes directly to human cells to replace defective genes that are causing disease. Gene therapy takes advantage of viruses' modus operandi -- injecting genetic material into cells. But instead of forcing in harmful, viral DNA, gene therapy delivers helpful, functional genes. Controlled packaging of the functional genes into the viral delivery system is one of the key factors involved in developing a successful gene therapy.

Many viruses, whether they infect bacteria, plants or animals, are adept at packing long stretches of nucleic acid (DNA or RNA) within their nanometer-sized protein shells. In many of the viruses that contain double-stranded DNA, the DNA gets packaged so tightly that it bends upon itself, resulting in repulsive forces that exert a tremendous amount of pressure on the virus's outer shell, indicating a great amount of stored energy. At the moment of infection, when the DNA is being shot out of the virus, the energy stored in the tightly packed DNA is released and converted into thermal energy.

Evilevitch and his colleagues from Lund University in Sweden, where Evilevitch was previously employed, and the Universite de Lyon in France used an experimental technique known as isothermal titration calorimetry (ITC) to directly measure the heat, and thus the thermal energy, released during viral genome ejection. Until now, only indirect measurements of this energy have been available. They describe this new method in the Feb. 5 issue of the Journal of Molecular Biology.

"We are the first group to use titration calorimetry to study genome release from viruses," Evilevitch said. "In this study, we looked at viruses that infect bacteria, called bacteriophages, as an experimental model system, but ITC can also be applied to other types of viruses. We're currently investigating the rotavirus, which causes stomach flu, using our new technique."

In the Journal of Molecular Biology report, Evilevitch used ITC to measure the thermal energy released during genome ejection, which is the same as the stored internal energy that results from genome packaging. His results, which agree with analytical models and computer simulations, show that the heat released increases as DNA length increases. He also discovered that the ordering of water molecules around DNA strands inside the virus (called hydration entropy) has a tremendous influence on the build up of energy. This unpredicted effect was not accounted for in the previous models.

"Understanding the energy profile for viral genome release provides information on how to interfere with the process. For example, developing ways to decrease the internal energy in viruses could prevent viruses from ejecting their genome and prevent infection," Evilevitch said.


Story Source:

The above story is based on materials provided by Carnegie Mellon University. Note: Materials may be edited for content and length.


Cite This Page:

Carnegie Mellon University. "First measurement of energy released from a virus during infection." ScienceDaily. ScienceDaily, 7 February 2010. <www.sciencedaily.com/releases/2010/02/100205102620.htm>.
Carnegie Mellon University. (2010, February 7). First measurement of energy released from a virus during infection. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2010/02/100205102620.htm
Carnegie Mellon University. "First measurement of energy released from a virus during infection." ScienceDaily. www.sciencedaily.com/releases/2010/02/100205102620.htm (accessed September 30, 2014).

Share This



More Plants & Animals News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

California University Designs Sustainable Winery

California University Designs Sustainable Winery

Reuters - US Online Video (Sep. 27, 2014) Amid California's worst drought in decades, scientists at UC Davis design a sustainable winery that includes a water recycling system. Vanessa Johnston reports. Video provided by Reuters
Powered by NewsLook.com
Argentina Worries Over Decline of Soybean Prices

Argentina Worries Over Decline of Soybean Prices

AFP (Sep. 27, 2014) The drop in price of soy on the international market is a cause for concern in Argentina, as soybean exports are a major source of income for Latin America's third largest economy. Duration: 01:10 Video provided by AFP
Powered by NewsLook.com
Mama Bear, Cubs Hang out in California Backyard

Mama Bear, Cubs Hang out in California Backyard

Reuters - US Online Video (Sep. 27, 2014) A mama bear and her two cubs climb trees, wrestle and take naps in the backyard of a Monrovia, California home. Vanessa Johnston reports. Video provided by Reuters
Powered by NewsLook.com
'Crazy' Climate Forces Colombian Farmers to Adapt

'Crazy' Climate Forces Colombian Farmers to Adapt

AFP (Sep. 26, 2014) Once upon a time, farming was a blissfully low-tech business on Colombia's northern plains. Duration: 02:05 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins