I'll Take the Flu Shot, Hold the Eggs

11 April 2007 (All day)


The end for eggs?
Vaccine production in eggs--including the quality control procedure shown in this picture--would become obsolete if a new vaccine succeeds.

Easter may have come and gone, but manufacturers of flu vaccines are always hunting for eggs. Chicken eggs are needed to grow the viruses used in vaccines, and a large amount of vaccine--such as would be needed in an influenza pandemic--requires lots of eggs. Now scientists may have found a better way. A study suggests that vast quantities of vaccine might be more easily made in insect cells than in eggs.

The new approach takes the virus out of the equation. Instead of growing a virus in an egg and injecting people with a "killed" version, the strategy, in the works for more than a decade, involves harvesting just one viral protein. Researchers at Protein Sciences Corporation, a small biotech in Meriden, Connecticut, genetically modified a virus that infects caterpillar cells to produces hemagglutinin, a coat protein of the influenza virus that triggers antibodies. The method is much less cumbersome than dealing with chicken eggs, and because the vaccine is so easy to produce, the company intends to use 135 micrograms of hemagglutinin in each dose of vaccine--3 times higher than current flu vaccines--in hopes of getting better protection.

To see if that approach will work, a team led by John Treanor of the University of Rochester Medical Center in New York recruited 460 healthy adults at three medical centers. The researchers found that the 135-microgram vaccine triggered antibodies and produced only mild side effects. Preliminary evidence suggested that the vaccine wards off disease; none of the patients who received the vaccine developed influenza in the winter after they were vaccinated, compared to two in a group who received a lower dose, and seven in the placebo group, the team reports today in the Journal of the American Medical Association. A larger efficacy study in 4000 people is planned for later this year.

Using the same technology, it would be "really very simple" to make a pandemic vaccine, says Manon Cox, Protein Sciences' chief operating officer. That's a crucial advantage, says David Fedson, a vaccine expert and retired pharma executive in Sergy-Haut, France. If, after the start of a pandemic, pharmaceutical bioreactors around the world could be harnessed to make the vaccine, billions of doses could be produced in a matter of months, potentially saving millions of lives.

Such speed would allay the worries of developing countries such as Indonesia, which recently stopped sharing flu samples with the World Heath Organization because it fears it will be left in the cold when a pandemic strikes, Fedson says. "That makes this paper very, very pertinent."

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