Researchers move closer to discovering hepatitis C vaccine

573 mots
15 février 2012
Postmedia News
Anglais
Copyright © 2012 Canwest News Service
University of Alberta researchers are a step closer to developing a vaccine against hepatitis C that could work against major strains of the disease, they say.

Michael Houghton told a Vancouver scientific summit that the vaccine prototype has been tested in humans and is capable of causing an immune response. He presented the findings Wednesday during a Canada Excellence Research Chairs summit at Robson Square. The meeting was held on the eve of the world’s biggest science gathering – the American Association for the Advancement of Science (AAAS) meeting.

The AAAS meeting is expected to draw about 8,000 scientists and 700 journalists from over 50 countries. The last time the meeting was held in Canada was 31 years ago in Toronto. Alan Leshner, CEO of AAAS, told a Vancouver Sun editorial board session Wednesday that holding the meeting in Vancouver is an “experiment” that is already proving its worth as hundreds of Canadian academics have helped organize the meeting and will communicate their research over the next five days.

Houghton said there are six major strains of hepatitis C and hundreds more subtypes infecting 170 million people around the world. Hepatitis C is spread through contaminated blood and can be associated with needle-sharing, medical procedures involving unsterilized equipment, or blood transfusions.

He said the vaccine is made from one strain of the hepatitis disease, but produces antibodies that can neutralize a variety of hepatitis C strains.

“I think that’s great news for our efforts to develop a vaccine for hepatitis C,” said Houghton, an expert in microbiology and immunology whose work led to the discovery of the hepatitis C virus in 1989.

The finding has been unexpected because a vaccine was considered impractical, if not impossible, since hepatitis C is more heterogeneous – has more varieties – than HIV.

“In the HIV field, for example, it’s been the Holy Grail for many years to try to elicit antibodies that can neutralize all the different types around the world,” Houghton said.

“I think it’s a very big step forward,” he said. “I’ve been working on the vaccine for 15 years [and] for so many years, the field felt that antibodies would be very restricted in their neutralizing ability, that you could only neutralize the same strain that the vaccine was derived from.”

John Law, Houghton’s research partner, said preliminary tests showed the vaccine success appears to be more effective at higher doses. It could take seven years before it’s available, however, because it must be tested in large clinical trials. Of the millions who carry the infection, up to 20 per cent develop chronic illness, including cirrhosis of the liver.

Drugs to treat the disease are now available and Houghton said it is possible the vaccine might be used in combination.
Dr. Lorne Tyrrell, a hepatitis expert and the Canadian Institutes of Health Research and GlaxoSmithKline chair in virology at the U of A, said a vaccine would have a global impact. In Egypt, for example, 10 per cent of the population carries hepatitis C.

“In many parts of the world, the antiviral therapy we currently have for hepatitis C is often out of the reach of most people’s affordability so having a [cheaper] vaccine that could be used to prevent the disease in those countries is particularly important,” Tyrrell said.
 
 
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