Featured Research

from universities, journals, and other organizations

Viruses are as simple as they are 'smart'

Date:
November 25, 2013
Source:
Sissa Medialab
Summary:
Viruses are as simple as they are “smart”: too elementary to be able to reproduce by themselves, they exploit the reproductive “machinery” of cells, by inserting pieces of their own DNA so that it is transcribed by the host cell. To do this, they first have to inject their own genetic material into the cells they infect. An international team of researchers has studied how this occurs and how long it takes for this process to be completed.

Viruses are as simple as they are "smart": too elementary to be able to reproduce by themselves, they exploit the reproductive "machinery" of cells, by inserting pieces of their own DNA so that it is transcribed by the host cell. To do this, they first have to inject their own genetic material into the cells they infect. An international team of researchers, including Cristian Micheletti from SISSA (the International School for Advanced Studies in Trieste), has studied how this occurs and how long it takes for this process to be completed.

Micheletti and colleagues constructed a computer model of viral DNA and then simulated the release of genetic material from the viral capsid into the host cell nucleus. Far from being a fluid process, this ejection is subject to frictional forces that depend on the conformation of the DNA strand. "Fluidity of the process depends on how and how tightly the viral DNA is entangled," explains Micheletti. "The more topologically ordered is the double strand of the genome, the faster it is ejected from the virus. The situation is somewhat similar to the behaviour of an anchor line that has been correctly coiled: when the anchor is thrown overboard, the line uncoils neatly without stops or jerks due to tangles."

DNA has an intrinsic characteristic that makes its pattern of spontaneous arrangement very singular. Because it has two strands, DNA has a tendency to form highly ordered coils, just like anchor lines or thread spools. This isn't the case with generic polymers, which form complex and chaotic tangles. The simulations by Micheletti and colleagues compared the behaviour of a model strand of DNA and a simple strand of generic polymer. "In 95% of cases the model DNA slid through the exit pore of the virus much faster than the simple polymer, as a result of the greater spontaneous order of its conformation," comments Micheletti. "The simple strands may be even ten times slower than the DNA strands. Another interesting thing is that, although much more slowly, the simple strands in our observations always succeeded in leaving the virus completely. By contrast, in a small minority of cases, the DNA remained totally blocked, and this too is related to its tendency to form a spool that may sometimes present such complex torus knots -- i.e., doughnut-like -- to completely block ejection from the virus."

The process timescales observed by Micheletti and colleagues are perfectly consistent with empirical observations, "including all cases of complete DNA stalling that have been reported, though not explained, in some experiments," concludes Micheletti. "Our study, which estimated the time it takes viral DNA to leave the capsid in relation to its length and degree of packing could provide the starting point for designing artificial viral vectors."

The study has just been published in the Proceedings of the National Academy of Sciences (PNAS).


Story Source:

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


Journal Reference:

  1. D. Marenduzzo, C. Micheletti, E. Orlandini, D. W. Sumners. Topological friction strongly affects viral DNA ejection. Proceedings of the National Academy of Sciences, 2013; DOI: 10.1073/pnas.1306601110

Cite This Page:

Sissa Medialab. "Viruses are as simple as they are 'smart'." ScienceDaily. ScienceDaily, 25 November 2013. <www.sciencedaily.com/releases/2013/11/131125091318.htm>.
Sissa Medialab. (2013, November 25). Viruses are as simple as they are 'smart'. ScienceDaily. Retrieved August 29, 2014 from www.sciencedaily.com/releases/2013/11/131125091318.htm
Sissa Medialab. "Viruses are as simple as they are 'smart'." ScienceDaily. www.sciencedaily.com/releases/2013/11/131125091318.htm (accessed August 29, 2014).

Share This




More Health & Medicine News

Friday, August 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Killer Amoeba Found in Louisiana Water System

Killer Amoeba Found in Louisiana Water System

AP (Aug. 28, 2014) State health officials say testing has confirmed the presence of a killer amoeba in a water system serving three St. John the Baptist Parish towns. (Aug. 28) Video provided by AP
Powered by NewsLook.com
Who Could Be Burnt by WHO's E-Cigs Move?

Who Could Be Burnt by WHO's E-Cigs Move?

Reuters - Business Video Online (Aug. 28, 2014) The World Health Organisation has called for the regulation of electronic cigarettes as both tobacco and medical products. Ciara Lee looks at the impact of the move on the tobacco industry. Video provided by Reuters
Powered by NewsLook.com
CDC Director On Ebola Outbreak: 'It's Worse Than I Feared'

CDC Director On Ebola Outbreak: 'It's Worse Than I Feared'

Newsy (Aug. 28, 2014) CDC director Tom Frieden says the Ebola outbreak is even worse than he feared. But he also said there's still hope to contain it. Video provided by Newsy
Powered by NewsLook.com
How A 'Rule Of Thumb' Could Slow Down Drinking

How A 'Rule Of Thumb' Could Slow Down Drinking

Newsy (Aug. 28, 2014) A study suggests people who follow a "rule of thumb" when pouring wine dispense less than those who don't have a particular amount in mind. Video provided by Newsy
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:
from the past week

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