主题：【分享】加拿大首次完成甲型H1N1流感病毒基因测序

Canadian scientists working through the night to pick apart the genes of the human swine flu bug have, in a world first, sequenced the virus in a Winnipeg laboratory.


"This is the first complete sequencing of the H1N1 flu virus and it's vitally important to our understanding of this outbreak," Federal Health Minister Leona Aglukkaq said.


Genetic sequencing involves decoding the basic building blocks of the virus.


"This is a world first and a real validation of Canada's scientific excellence," Aglukkaq said.


Samples of virus taken from Nova Scotia and Ontario and samples from Mexico appear to be a genetic match. The team found nothing to explain at the genetic level why the virus is causing severe pneumonia and deaths in Mexico, while cases in Canada and the U.S. have been mostly mild.


"That's one of the big questions that everybody has been asking," said Dr. Frank Plummer, scientific director general of the National Microbiology Laboratory in Winnipeg.


"It's likely not the virus itself that is explaining the differential in severity of disease between Mexico and the rest of North America."


Cracking the genetic code of the virus moves scientists an important step closer to understanding how swine flu spreads and changes over time, how long it has been in the human population, and where it originated. It will also help in the development of a vaccine.


The genetic sequences of the three viruses have been sent to GenBank, a public database where genetic sequences can be studied and compared by scientists around the world. "This is a significant and important milestone for us, but there is still a lot more work ahead of us," Plummer said.


Officials also said Wednesday the outbreak of swine flu in a central Alberta hog farm has been contained.


Officials believe the pigs contracted the virus from a Canadian worker who returned from Mexico on April 12 and arrived on the farm two days later. It is the first known human to swine transmission of the H1N1 flu virus. Officials said the pigs have recovered, or are recovering, and that no decision has been taken to cull the herd.


"We can reassure Canadians unequivocally that the situation remains contained on that farm," said Dr. Brian Evans, Canada's chief veterinary officer.


Evans said the pigs from the Alberta hog farm could enter the food supply once they have recovered and are shown to pose no threat to human health.


"If we can satisfy ourselves that this virus behaves no differently in swine than any other influenza virus, then our approach on this will be to manage this in the most prudent responsible way to protect public health," said Evans, executive vice-president of the Canadian Food Inspection Agency.


"If it is determined that virus-negative pigs do not pose a risk in the food supply . . . then we would be moving in that direction."


He said the standard operating practice in Canada "is the fact that you do not slaughter sick animals and you do not slaughter dead animals for human consumption."


The World Health Organization was warning Wednesday that meat from pigs infected with the new H1N1 virus shouldn't be used for human consumption. WHO's comments appear more cautious than those from the Food and Agriculture Organization (FAO) and World Organization for Animal Health (OIE), which said import bans are not required to safeguard public health because the disease isn't food-borne and has not been identified in dead animal tissue.


WHO, however, said it was possible for flu viruses to survive the freezing process and be present in thawed meat, as well as in blood.


"Meat from sick pigs or pigs found dead should not be processed or used for human consumption under any circumstances," Jorgen Schlundt, director of WHO's Department of Food Safety, Zoonoses and Foodborne Diseases.


Canada's total number of confirmed cases of swine flu stands at 201.


Canada's public health agency confirmed 36 new cases across the country Wednesday. Eight new cases were confirmed in B.C., four in Alberta, 13 in Ontario, six in Quebec and five in Nova Scotia.


In Montreal, Michel C. Dore, an official with the Civil Security department, said that some employers are asking staff returning from Mexico to get a certificate of good health before resuming their work.


"Not only are these requirements are against public health recommendations in Quebec but furthermore they could overburden the health system," he said.


In Edmonton, medical-supplies manufacturer priMED is turning away desperate requests for masks because its Chinese plant can't keep up with the demand sparked by swine flu.


The Edmonton company's facility at Liyang, two hours west of Shanghai, is running 24 hours a day supplying the extra orders from its regular customers, chairman Chris Thompson said Wednesday. "We're getting lots of calls from RCMP detachments and school districts, but we can't supply them because of existing contracts and customers. It's really unfortunate because you can hear the desperation in their voices."


Meanwhile, after mounting a spirited defence of its decision to quarantine a group of Canadian students and their teacher, China relented Wednesday and let them go.


The 27 students from the Universite de Montreal and Laval had been under quarantine in Changchun, in northeastern China, for suspected H1N1 flu since last Saturday. None had any recent contact with a flu victim or had shown any symptoms before they were summarily sequestered when they arrived to begin a 10-week language course.


On Wednesday, WHO raised its global totals to 1,658 confirmed cases of swine flu in 23 countries. The disease is believed to have caused 31 deaths worldwide.


In Mexico, as its capital began to stir back to life Wednesday, the country cut its confirmed death toll from the HIN1 flu to 42, as dozens of test samples came back negative.


The streets of Mexico City were again clogged with traffic and vendors working the sidewalks after authorities lifted a five-day shutdown to try to contain swine flu.


The world health agency could decide as early as next week whether to recommend that drug manufacturers start full-scale production of a swine-flu vaccine, once one is developed.


Many developed countries, including Canada, already have agreements with drug companies to ensure supply of a pandemic vaccine. Canada has a contract with GlaxoSmithKline Biologicals to supply enough vaccine for the entire Canadian population in the event of a pandemic, according to the federal government.


However, it is not yet clear if Canada would have to line up behind other countries to receive its supply.