DNA Could Hold An Answer To The Vaccine Dilemma
Wednesday, September 30, 2009
San Diego should be receiving its first batches of swine flu vaccine in a couple of weeks. The H1N1 virus has seen very little mutation so far, and that means the vaccine should work. But that could change because flu viruses are notoriously adaptive. Two San Diego companies think they've found an answer in a new kind of vaccine.
SAN DIEGO San Diego should be receiving its first batches of swine flu vaccine in a couple of weeks. The H1N1 virus has seen very little mutation so far, and that means the vaccine should work. But that could change because flu viruses are notoriously adaptive. Two San Diego companies think they've found an answer in a new kind of vaccine.
The vaccine is a miracle of modern medicine. But some people in San Diego's biotech community wonder why the method of making vaccines is virtually unchanged since Jonas Salk discovered the polio vaccine in 1955. One of those people who's wondering why is Vijay Samant, the CEO of Vical Incorporated.
"We are throwing money at a solution that is a 50 or 75-year-old solution," he said. "This is a smart country. We should be thinking, 'Okay… what am I going to do in the future?'"
Vical is a company that has pioneered what's called the DNA vaccine. Vical and another San Diego company, Inovio, have had success with DNA vaccines in animal tests against numerous flu strains. Human trials are yet to come. The same is true of FDA approval.
DNA vaccines use the genetic sequence of a virus to create a kind of viral blueprint. That blueprint is injected into a person's muscle cells, which respond by recreating the virus in a harmless but distinguishable form. The body's immune system then creates antibodies that kill the virus and stand ready for any future invaders.
Samant explains by use of a sartorial metaphor.
"If I'm a pathogen wearing a blue jacket, and that's a distinguishing feature that anywhere I go I wear this blue jacket, then all I need is the genetic recipe for the sequence of the blue jacket. I put it in a ring of DNA, then that recipe is taken by the muscle cells which make copies of the blue jacket which the immune system recognizes. So when a real pathogen wearing the blue jacket comes in, it's prepared."
Conventional vaccines follow a very different recipe. Manufacturers grow the actual virus in eggs. They then kill the virus to make it safe and a nurse injects it into your arm. Robert Schooley is a virologist and head of the infectious disease division at UCSD School of Medicinel.
"This has been done for years and years and it's done in a way that doesn't vary from the previous year. So regulators don't have to make any other decisions than to say it worked last year -- let's try it again this year," said Schooley.
But while the conventional method is tried and bona fide, it's far from perfect. The process of growing viruses in eggs poses a serious risk of contamination. This happened recently when a large vaccine plant in England was hit with salmonella. Vaccines grown in eggs can create problems for people with egg allergies. Also, purifying hundreds of thousands of eggs, and then growing viruses in them, takes months. And the longer it takes between the time a virus is targeted, and the time its vaccine is produced, the longer the virus has to mutate. This can render the vaccine ineffective.
Schooley says a DNA vaccine, by comparison, could be produced in a week. He says the problem with DNA vaccines is they're new.
"If you go to the FDA and say, 'The vaccine is done in a very different way, and we've done some studies in a few humans and it looks pretty good.' Then they FDA says that all looks good, but do we know it works as well," he said.
So far, the success of Vical and Inovio's DNA vaccines has been shown in animal trials and in the investment markets. Since the arrival of the H1N1 virus, Vical's stock value has doubled, while Inovio's has quadrupled. Keep in mind that that Inovio's stock was worth less than 50 cents on May 1.
Whatever the fate of these San Diego biotechs, Vical CEO Vijay Samant say the world needs a better way to respond to flu pandemics than using the old fashioned vaccine.
"This concept of pandemics as a novelty is going to quickly fade away," said Samant. "We're going to be constantly besieged by pandemics for three reasons."
He says those reasons are the possible effects of global warming, close contact with domestic animals and, above all, the great mobility of people in today's global village.