현재 유행하고 있는 돼지 인플루엔자 바이러스 H1N1의 표면에 존재하는 단백질이 인간의 호흡기 상피세포의 수용체에 결합하는 능력이 별로 뛰어나지 않다는 연구결과가 [사이언스]지 최신호에 실렸습니다.
미국 CDC 및 하바드-매사추세츠 공동 연구팀은 돼지독감 바이러스는 폐와 위에 감염이 일어나며, 계절성 독감 바이러스는 폐에만 감염이 일어나는 등 돼지독감 바이러스와 일반적인 계절성 독감 바이러스의 차이를 밝혔습니다.
따라서 돼지독감 바이러스가 인체 전염능력을 가지고 있다고 하더라도 그 전파는 제한적일 것이라는 추정이 가능합니다.
그러나 연구팀은 인플루엔자 바이러스는 돌연변이가 빠른데다 이번 바이러스는 위장 내에서 오랫동안 머무를 수 있는 특성이 있어 쉽게 전파될 수 있기 때문에 경계를 늦추어선 안 된다고 밝혔습니다.
반면 사이언스에 실린 덴마크 연구팀의 논문은 미국 CDC연구팀과 다르게 돼지독감 바이러스는 계절성 독감 바이러스와 똑같이 동물에게 전염을 잘 일으킨다고 밝히고 있습니다.
연구자들 사이에서도 의견이 갈리고 있는 등 돼지독감에 대한 불확실성은 여전히 해소되지 않고 있는 상황입니다.
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Reports
Transmission and Pathogenesis of Swine-Origin 2009 A(H1N1) Influenza Viruses in Ferrets and Mice
출처 : Originally published in Science Express on 2 July 2009
Science 24 July 2009:
Vol. 325. no. 5939, pp. 484 – 487
DOI: 10.1126/science.1177238
2 Harvard–Massachusetts Institute of Technology (MIT) Division of Health Sciences and Technology and Koch Institute for Integrative Cancer Research, Department of Biological Engineering, MIT, E25-519, Cambridge, MA 02139, USA.
* To whom correspondence should be addressed. E-mail: tft9@cdc.gov
The editors suggest the following Related Resources on Science sites:
In Science Magazine
- REPORTS
- Vincent J. Munster, Emmie de Wit, Judith M. A. van den Brand, Sander Herfst, Eefje J. A. Schrauwen, Theo M. Bestebroer, David van de Vijver, Charles A. Boucher, Marion Koopmans, Guus F. Rimmelzwaan, Thijs Kuiken, Albert D. M. E. Osterhaus, and Ron A. M. Fouchier (24 July 2009)
Science 325 (5939), 481. [DOI: 10.1126/science.1177127]
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Study: New flu inefficient in attacking people
WASHINGTON – With swine flu continuing to spread around the world, researchers say they have found the reason it is — so far — more a series of local blazes than a wide-raging wildfire. The new virus, H1N1, has a protein on its surface that is not very efficient at binding with receptors in people’s respiratory tracts, researchers at the Harvard-MIT Division of Health Sciences and Technology report in Friday’s edition of the journal Science.
“While the virus is able to bind human receptors, it clearly appears to be restricted,” Ram Sasisekharan, lead author of the report, said in a statement.
But flu viruses are known to mutate rapidly, the research team noted, so this one must be watched closely in case it changes to become easier to spread.
Even if it doesn’t mutate, it’s causing plenty of illness here and abroad already — and vaccine makers are working “at full speed” to develop shots for use in the fall if the government deems it enough of a threat, Dr. Anthony Fauci, infectious disease director of the National Institutes of Health, said Thursday.
Within a few weeks, Fauci expects to receive the first test batches for government-led studies in volunteers to see if the vaccine triggers signs of immune protection, at what dose and is safe.
The results of those tests will help the U.S. government decide whether to distribute swine flu vaccine in the fall, how much, and whether children or others should be first to get it.
The government wants public input before it makes any decisions, Dr. Anne Schuchat of the Centers for Disease Control and Prevention told a meeting of the American Association for the Advancement of Science on Thursday.
Good news: The swine flu virus circulating today “is molecularly strikingly similar” to the spring’s first cases, making it likely that any vaccine could be “a perfect match,” Fauci added.
Worldwide, more than 300 people have died and more than 70,000 cases have been confirmed, according to the World Health Organization, which last month officially declared the virus a pandemic.
It’s currently flu season in the Southern Hemisphere, and viral spread in Argentina has prompted schools there to give students an early vacation. But swine flu hasn’t abated in the Northern Hemisphere, unusual since influenza usually retreats from summer’s high heat and humidity. Confirmed U.S. cases have reached nearly 34,000 — a fraction of the infected are tested — and deaths rose 34 percent in the past week to hit 170, the CDC said Thursday. England’s health minister said Thursday that his country faces a projected 100,000 new swine flu cases a day by the end of August.
Also Thursday, Health and Human Services Secretary Kathleen Sebelius said the U.S. will provide 420,000 treatment courses of the anti-viral medicine Tamiflu to the Pan-American Health Organization to help fight the flu in Latin America and the Caribbean. “All of us have a responsibility to help support one another in the face of this challenge,” Sebelius said at a meeting of health ministers in Mexico.
Sasisekharan’s paper, meanwhile, warned that the H1N1 strain might just need a single change or mutation to make it resistant to Tamiflu.
The researchers also noted that the new virus is more active in the gastrointestinal tract than seasonal flu, leading to intestinal distress and vomiting in about 40 percent of those infected.
The research was funded by the Singapore-MIT Alliance for Research and Technology and the National Institutes of General Medical Sciences.
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AP Medical Writer Lauran Neergaard contributed to this report.
On the Net:
Science: http://www.sciencemag.org
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New flu may not spread like regular flu
출처 : 로이터통신 Thu Jul 2, 5:01 pm ET
WASHINGTON (Reuters) – The new H1N1 influenza strain may be just a little less catching than seasonal flu, but seems a little better able to cause stomach upsets, researchers reported on Thursday.
Genetic analysis and lab experiments with the virus show it lacks a piece of genetic material that makes ordinary flu viruses so transmissible, a team of U.S. researchers found.
Researchers in the Netherlands, meanwhile, found it lives very well in the nose and their findings suggest it has the ability to stay around for a long time — and get worse.
Both studies, published in the journal Science, show that H1N1 swine flu needs to be closely watched, said Dr. Terrence Tumpey of the U.S. Centers for Disease Control and Prevention.
“I think the take-home message is that we really need to keep a close eye on this virus,” Tumpey said in a telephone interview.
Last month the World Health Organization declared a pandemic of the new swine flu. It has been confirmed in more than 77,000 people globally and has killed at least 332 people, but U.S. officials have said there are likely a million or more cases in the United States alone.
Although flu season usually ends in April in the Northern Hemisphere, the new virus is still causing widespread illness and it is actively in the mix of seasonal flu viruses now circulating during the Southern Hemisphere’s winter.
Tumpey and colleagues tested samples of the new virus from a California child who recovered from a mild bout with the new flu, a Texas child who died and a Mexican woman who had severe disease.
They compared it to ordinary, seasonal H1N1 flu, testing it in ferrets, which develop flu in ways similar to humans.
The ferrets did not catch the new swine flu from one another as easily as they catch ordinary viruses, Tumpey said. Usually, if a ferret is infected with human flu, it infects all other ferrets in nearby cages. But with the new H1N1, only six out of nine animals became infected.
HOUSEHOLD SPREAD
Usually 20 percent to 30 percent of household members are infected by a single flu patient but H1N1 swine flu may have a lower transmission rate, Tumpey said.
In addition, all previous pandemic flu strains — from 1918, 1957 and 1968 — have had a specific genetic sequence in a gene called PB2. The new H1N1 does not have this particular mutation, Tumpey said.
He said health officials should keep an eye out for it, as the change may signal the virus is gaining the ability to spread more quickly and easily than it already does. Researchers are also watching for signs the virus has developed mutations that allow it to resist antiviral drugs — and have found two instances so far, one in Japan and one in Denmark.
In addition, Tumpey’s team found mutations that let the new H1N1 virus live in the small intestine — something seasonal influenza cannot do. This may explain why so many swine flu patients have stomach upsets such as nausea and diarrhea, the researchers said.
In the other report, Ron Fouchier and colleagues at Erasmus Medical Center in Rotterdam found the virus lived well in ferrets and spread very easily from one to another.
In fact, ferrets shed more virus with new H1N1 than with seasonal flu — meaning more of it came out of their noses, Fouchier’s team found.
Ferrets inoculated with the new swine flu virus were a little sicker and took a little longer to recover than ferrets infected with seasonal H1N1.
“These data suggest that the 2009A(H1N1) influenza virus has the ability to persist in the human population, potentially with more severe clinical consequences,” they wrote.
(Editing by Mohammad Zargham)
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Why Swine Flu Differs From Seasonal Flu
출처 : 포브스 07.02.09, 02:00 PM EDT http://www.forbes.com/feeds/hscout/2009/07/02/hscout628674.html?feed=rss_forbeslife_health
Pandemic virus affects lungs and stomach, whereas seasonal flu doesn’t, researchers say
THURSDAY, July 2 (HealthDay News) — Scientists have uncovered some intriguing clues about why the new swine flu frequently brings on gastrointestinal distress and vomiting, symptoms not usually associated with seasonal flu.
In experiments with ferrets, research teams in the United States and the Netherlands found that the new H1N1 flu virus replicated more extensively in the respiratory tract, going to the lungs, whereas the seasonal flu virus stayed in the animals’ nasal cavity. The U.S. team also found that the new virus, unlike the seasonal one, went into the ferrets’ intestinal tract.
Such distinctions, the U.S. researchers said, can make a difference in establishing appropriate public health responses as the pandemic continues around the world, so far sickening more than a million people in the United States alone.
“Findings from the study demonstrate that, in ferrets, the novel 2009 H1N1 influenza virus leads to increased morbidity and increased respiratory disease when compared to contemporary seasonal human influenza viruses,” said researcher Terrence M. Tumpey, a senior microbiologist in the influenza branch of the U.S. Centers for Disease Control and Prevention in Atlanta.
“Additionally, virus transmission was less effective in ferrets infected intranasally with novel 2009 H1N1 influenza virus, compared to those infected with contemporary seasonal human influenza viruses,” he added.
The reports are published in the July 2 online edition of Science.
When both teams looked at how easily the new H1N1 virus can be transmitted, they came to different conclusions, however.
The Dutch researchers found that the new H1N1 virus and the seasonal flu virus were equally good in infecting the animals.
But Tumpey’s team found that the swine flu virus might not be transmitted as easily as the seasonal flu virus. “The novel 2009 H1N1 influenza viruses exhibited less efficient respiratory droplet transmission in ferrets, in comparison to the high-transmissibility of a seasonal H1N1 virus,” he said.
Ferrets are used to study influenza because the flu virus affects them in a similar way to humans, the researchers noted.
“One thing we know for sure about influenza viruses is that they are unpredictable,” Tumpey added. “The characteristics that the virus is displaying today might not hold true in the upcoming months.”
It is important to remember, he said, that this is a new influenza virus never seen in humans before April 2009.
“The virus does not appear to be fully adapted to its new human host,” Tumpey said. “How the virus may adapt further as it circulates among people is not known. However, this uncertainty makes it imperative that the virus and the epidemiology of the outbreak be closely monitored.”
Dr. Pascal James Imperato, dean of the School of Public Health at SUNY Downstate Medical Center in New York City, found the new research added key information to what was already known.
“In this study, it was found that the 2009 H1N1 virus was less efficiently transmitted by droplet infection in ferrets compared to the seasonal human H1N1 virus,” Imperato said. “This is a significant finding as it indicates that the 2009 swine flu virus might not be as easily transmitted between humans as its seasonal counterpart.”
On the other hand, he added, the findings also “collectively demonstrate that it has the potential to cause serious clinical illness that also results in gastrointestinal symptoms, which were, in fact, observed in a number of patients.”
On June 11, the World Health Organization declared the first flu pandemic since 1968, triggered by the rapid spread of the H1N1 swine flu virus across North America, Australia, South America, Europe and regions beyond. Two weeks ago, U.S. health officials said they were considering a swine flu immunization campaign that could involve an unprecedented 600 million doses of vaccine. That would dwarf the 115 million vaccine doses given annually for seasonal flu.
More information
The U.S. Centers for Disease Control and Prevention has more on swine flu.
