Featured Research

from universities, journals, and other organizations

Scientists Unravel Critical Genetic Puzzle For Flu Virus Replication

Date:
January 27, 2006
Source:
University of Wisconsin-Madison
Summary:
Much is known about the genes and inner workings of flu viruses. Yet how the microbe organizes its genetic contents to seed future generations of viruses has remained an enduring mystery of biology. Now, with the help of a long-studied flu virus, an electron microscope and a novel idea of how the virus aligns segments of RNA as it prepares to make virions, the particles a virus creates and sends forth to infect cells, that puzzle has been resolved.

Viewed as a cross section, a nascent influenza A virus, the same family of flu viruses that includes avian forms of influenza, reveal how the virus organizes its genetic material as it prepares to bud from a cell to infect other cells. The RNA fragments that make up the viral genome always organize in a circle of seven around another genetic element. Knowing that flu viruses organize their genetic contents in a specified way, a finding made by UW-Madison influenza researcher Yoshihiro Kawaoka, may help scientists find new antiviral compounds and harness the flu virus to speed and optimize vaccine production.
Credit: Photo : courtesy Yoshihiro Kawaoka

Like any other organism, an influenza virus's success in life is measured by its genetic track record, its ability to pass on genes from one generation to the next.

But while much is known about the genes and inner workings of flu viruses, how the microbe organizes its genetic contents to seed future generations of viruses has remained an enduring mystery of biology.

Now, with the help of a long-studied flu virus, an electron microscope and a novel idea of how the virus aligns segments of RNA as it prepares to make virions, the particles a virus creates and sends forth to infect cells, that puzzle has been resolved.

The new work, which is reported in this week's (Jan. 26, 2006) edition of the journal Nature, is important because it presents opportunities to design new antiviral drugs and harness flu viruses for speedier, more efficient vaccine production. The work is especially critical as the biomedical community and governments worldwide develop strategies to cope with the prospect of an avian influenza pandemic.

"We've found that the influenza virus has a specific mechanism that permits it to package its genetic materials" as it creates its infectious particles, says Yoshihiro Kawaoka, a University of Wisconsin-Madison School of Veterinary Medicine professor and a leading influenza researcher. Kawaoka is also a professor at the University of Tokyo.

Viruses, including influenza viruses, depend on the cells of their hosts to survive. They infect cells and use them to help make more infectious particles, which are released from the cell and go on to infect other cells.

Using a technique known as electron tomography, a method that enables scientists to generate three-dimensional images of microscopic organisms and structures, Kawaoka and his colleagues, in virtual fashion, dissected a virus and its infectious particles to assess how the virus assembles and organizes the strands of RNA that carry its genes so it can exit one cell and go on to infect other cells.

What Kawaoka found was that the viruses were assembling their infectious genetic elements in a systematic fashion. Virologists have long debated whether the RNA segments in flu viruses assembled at random into the virions or were somehow incorporated into the infectious particle in an organized way.

The RNA segments, according to Kawaoka, form in a distinct pattern abutting the membrane of the virus. They are always arranged in a circle of seven surrounding another segment for a total of eight RNA fragments.

"It was not really known whether the fragments were coming as a set," explains Kawaoka, whose team conducted the work using a long-studied influenza A virus, the family responsible for regular influenza outbreaks, including such medical calamities as the 1918 influenza pandemic.

The fact that the virus requires a systematic -- as opposed to a random -- method of assembly opens the door to the development of new antiviral drugs and the harnessing of benign influenza viruses as gene vectors to optimize vaccine production, Kawaoka says.

"We need to have more antivirals for influenza," according to Kawaoka, "and as these segments get incorporated into the particle as a set, it suggests these elements could be a target for disruption. There must be a genetic element in each of the eight segments that allows them to interact."

What's more, scientists have been exploring the possibility of using strains of influenza to ferry genes from one virus to another to speed and optimize vaccine production. More efficient methods of vaccine production will be critical should a global outbreak such as the "Spanish " flu pandemic of 1918 recur. That pandemic killed an estimated 30-50 million people.

Knowing how influenza A viruses package their genetic contents, and knowing that they do so systematically, suggests it may be possible, by manipulating key genetic elements, to quickly engineer viruses that can be used to mass produce vaccines. Researchers have been trying to make viral vectors using nine genetic segments, a strategy that has never worked, Kawaoka notes.

"To develop an influenza virus vector, we have to stick to this eight-segment concept," he says.

Such a strategy may be useful for developing vaccines for a range of diseases, including HIV, the virus that causes AIDS, Kawaoka adds.

The new work, according to Kawaoka, benefited from a critical observation made possible by the dissection of the virus and its virions. The virus particles, when observed as a cross section, always displayed the circle of seven RNA fragments surrounding another segment pattern.

"No one has identified this before, perhaps because no one has ever tried to make serial sections of the virus."

###

In addition to Kawaoka, authors of the new Nature paper include Takeshi Noda, Hiroshi Sagara of the University of Tokyo; Albert Yen and Holland Cheng of the Karolinska Institute, Sweden; Ayato Takada of Japan's Science and Technology Agency; and Hiroshi Kida of Hokkaido University. The work was funded by the Japan Science and Technology Agency; the Japanese Ministry of Education, Culture, Sports, Science and Technology; the Japanese Ministry of Health Labor and Welfare; the Swedish Research Council; and the U.S. National Institutes of Health.


Story Source:

The above story is based on materials provided by University of Wisconsin-Madison. Note: Materials may be edited for content and length.


Cite This Page:

University of Wisconsin-Madison. "Scientists Unravel Critical Genetic Puzzle For Flu Virus Replication." ScienceDaily. ScienceDaily, 27 January 2006. <www.sciencedaily.com/releases/2006/01/060126192058.htm>.
University of Wisconsin-Madison. (2006, January 27). Scientists Unravel Critical Genetic Puzzle For Flu Virus Replication. ScienceDaily. Retrieved October 1, 2014 from www.sciencedaily.com/releases/2006/01/060126192058.htm
University of Wisconsin-Madison. "Scientists Unravel Critical Genetic Puzzle For Flu Virus Replication." ScienceDaily. www.sciencedaily.com/releases/2006/01/060126192058.htm (accessed October 1, 2014).

Share This



More Health & Medicine News

Wednesday, October 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Pregnancy Spacing Could Have Big Impact On Autism Risks

Pregnancy Spacing Could Have Big Impact On Autism Risks

Newsy (Oct. 1, 2014) A new study says children born less than one year and more than five years after a sibling can have an increased risk for autism. Video provided by Newsy
Powered by NewsLook.com
Robotic Hair Restoration

Robotic Hair Restoration

Ivanhoe (Oct. 1, 2014) A new robotic procedure is changing the way we transplant hair. The ARTAS robot leaves no linear scarring and provides more natural results. Video provided by Ivanhoe
Powered by NewsLook.com
Insertable Cardiac Monitor

Insertable Cardiac Monitor

Ivanhoe (Oct. 1, 2014) A heart monitor the size of a paperclip that can save your life. The “Reveal Linq” allows a doctor to monitor patients with A-Fib on a continuous basis for up to 3 years! Video provided by Ivanhoe
Powered by NewsLook.com
Attacking Superbugs

Attacking Superbugs

Ivanhoe (Oct. 1, 2014) Two weapons hospitals can use to attack superbugs. Scientists in Ireland created a new gel resistant to superbugs, and a robot that can disinfect a room in minutes. Video provided by Ivanhoe
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


Health & Medicine

Mind & Brain

Living & Well

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