"It's a very good innovation - the most effective way to date and very promising technology. I think it's going to revolutionise the way we look at FMD vaccines around the world today” Dr Luis Rodriguez - Plum Island Animal Disease Center
domingo, 6 de maio de 2012
Foot-and-mouth disease vaccine developed in US
By Jane O'Brien
With the US livestock industry on alert after a diagnosis of "mad cow" disease in California, the BBC has gained rare access to a high-security compound where a vaccine for another deadly animal virus is close to completion.
Hijacked planes, dirty bombs and cyber attacks are all terror threats the US takes very seriously.
But there is another that many Americans may not have considered - foot-and-mouth disease.
The illness is one of the world's most contagious animal viruses. Although it does not infect humans, an outbreak in the US could cost the economy more than $50bn (£31bn), experts estimate.
To avert such a calamity, scientists working for the US government have spent several years developing a foot-and-mouth vaccine. It is expected to be licensed for use in the next few months.
Rodriguez, left, with colleague Jonathan Arzt, says the vaccine is one of the most innovative in decades
"This is probably one of the most important innovations in the last 60 years in foot-and-mouth disease," says Dr Luis Rodriguez, research leader of the foreign animal disease research unit at the Plum Island Animal Disease Center, where the vaccine has been developed under top security.
"FMD is one of the largest burdens on animal health and production around the world. We pay attention to it when it gets into non-endemic countries like the UK - and if it ever came into the US it would be big news.
"But FMD is a burden every day on the lives of millions people around the world."
Foot-and-mouth causes havoc because it spreads so quickly. It infects cloven-hoofed animals such as cows, pigs, sheep and goats. Infected livestock have to be quarantined and are usually killed. Trade involving meat, dairy and other animal products comes to a standstill.
Vaccines already exist but are of limited use because veterinarians cannot distinguish vaccinated animals from infected animals - both test positive for foot-and-mouth.
And it will also be safe to manufacture in the US because it does not use the whole live virus and cannot replicate, says Dr Larry Barrett, director of Plum Island, a US Department of Homeland Security installation.
"In the US, you can only work on FMD in an island environment, which is why we came here 60 years ago," he says. "They wouldn't allow us on the mainland."
A government-operated ferry is the only way to reach the facility, north of New York's Long Island and just off the coast of Connecticut. No food or drink is allowed off the island to reduce the risk the virus will escape onto the mainland.
The vaccine works by triggering an immune response. A part of the foot-and-mouth virus is placed in a harmless vector - in this case a defective human virus.
The vaccine is then injected into the animal, providing it with the relevant genetic information its immune system needs to fight the foot-and-mouth virus.
"The animal actually makes the vaccine inside its body by producing the FMD protein necessary to create an immune response," says Dr Rodriguez.
"It's a very good innovation - the most effective way to date and very promising technology. I think it's going to revolutionise the way we look at FMD vaccines around the world today."
Research into new vaccines is also underway at the Institute for Animal Health (IAH) in the UK. In 2001 Britain was hit by a severe foot-and-mouth disease outbreak that devastated the farming and tourism industries.
More than 10 million sheep, cows and pigs were slaughtered in an attempt to contain the outbreak. Images of burning carcasses became the hallmark of the crisis.
"The British government has funded this research so that we will have the tools available to support a 'vaccinate to live' policy should we have another outbreak," says Dr Bryan Charleston, head of the livestock viral diseases program at the IAH.
The work must be done on an island to guard against virus outbreaks
The foot-and-mouth virus is a genome surrounded by a coat of proteins. The new vaccines use only the proteins - not the live genome part of the virus - which is why they are safe to produce, the scientists say.That goal is still some years away, he says, but new approaches and scientific advances are giving cause for optimism.
Dr Charleston's British team is developing a vaccine that is produced in insect cells instead of a defective virus. Like the vaccine developed at Plum Island, it is extremely stable and can be deployed rapidly to stem an outbreak, he says.
"We have done the same sort of thing as scientists at Plum Island," he says.
"We just got there by a different route."
He hopes the vaccine will offer a longer lasting immunity to foot-and-mouth that will make it suitable for use in countries where the disease is endemic.
"In some cases current vaccines are only effective for three to four months which means livestock need to be vaccinated three or four times a year. The cost of gathering the animals alone is significant - it's just not practical," he says.
Only one major animal disease has been successfully eradicated so far - rinderpest - but scientists hope their work will one lead to the elimination of foot-and-mouth disease.
The last outbreak foot-and-mouth in the US occurred in 1929 and the biggest risk of the disease entering the country today comes mainly from infected animal imports.
There have been more than half a dozen high alerts already this year when samples from animals thought to be infected were flown by jet and helicopter to Plum Island for testing. All the cases turned out to be false alarms.