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Human Tests Conducted on Fast-Track Avian Flu Vaccine

Posted on: Thursday, 31 January 2008, 00:00 CST

University of Pittsburgh researchers have started human testing of an avian flu vaccine that protects mice against the deadliest and most common strain of the virus, officials announced Tuesday.

Pitt scientists developed a technology to produce the vaccine in two months, instead of the nine months typically required with live influenza viruses, according to the research published today by the Public Library of Science.

Speed is necessary, considering predictions that a mutated virus could reach pandemic levels within two weeks, scientists said.

"That is part of the excitement," said Dr. William Schaffner, who is professor and chair of the Preventive Medicine Department at Vanderbilt University Medical School and was not involved in Pitt's research. "Clearly a safe vaccine is important; safety should not be taken for granted. ... But speed, convenience, ease of production -- these are things that are important."

The World Health Organization announced four more cases of avian flu in Indonesia, bringing the number of known cases worldwide to 357, with 223 deaths.

Avian influenza, or bird flu, usually spreads to people through close contact with infected birds and does not spread easily from person to person. Scientists fear it will mutate, allowing for wide- scale human-to-human transmission. Since its appearance in Hong Kong in 2003, the virus has infected people in Asia, Europe and Africa.

Scientists are not sure what changes the avian flu virus would make in order to spread more easily, so they cannot develop a tailored vaccine. Instead they are creating vaccines that could protect against a variety of strains or could be made quickly, once a specific strain is known.

With money from Rockville, Md.-based vaccine company Novavax, Pitt concentrated on creating a vaccine that could be made quickly. Ted M. Ross, assistant professor at Pitt's Center for Vaccine Research, led the study and said the goal is to manufacture the vaccine within one month after health officials isolate the virus.

"Faster is better," said Ross. "What happens is, year after year, the virus keeps changing, so if you stockpile a vaccine now and the outbreak is in 2012, it will be ineffective."

Mathematical models show that a flu pandemic could sweep across the United States within two weeks, Ross said.

Flu vaccines typically are developed from live viruses grown in chicken eggs, a labor-intensive process that takes months. Pitt's vaccine is made from virus-like particles that the immune system recognizes as a real virus, but the particles don't contain the genetic information viruses use to reproduce.

The U.S. Food and Drug Administration licensed the first avian flu vaccine in April. It was developed by the pharmaceutical company sanofi pasteur and protects against a different strain of the virus than Pitt's vaccine.

Pitt has started small-scale testing of its vaccine in people to prove its safety and plans to expand the tests. However, the tests cannot show how well the vaccine protects people against avian influenza because researchers cannot ethically or safely infect people with the virus.

"Interim results show that (the vaccine) is well-tolerated by people and appears to be safe," Ross said. "We will never know for sure whether one of these vaccines protects a human until an outbreak occurs."

Terrence Tumpey, a senior microbiologist with the U.S. Centers for Disease Control and Prevention, assisted Pitt's team and said the CDC is encouraging the development of different types of avian flu vaccines in order to find the most effective ones.

"We were interested in working with (Pitt and Novavax) because of their technology of manufacturing vaccines in something other than eggs, and their ability to make vaccines in a shorter amount of time," Tumpey said.

Source: Tribune-Review/Pittsburgh Tribune-Review

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