Researchers call for FMD vaccine project

Britain's disastrous epidemic of foot and mouth disease (FMD) in 2001 cost the UK economy an estimated AUD$18 billion, and confirmed the what international veterinary authorities had feared: their insurance against the world's worst livestock disease had lapsed.

The epidemic, now believed to have been sparked by virus-contaminated imported meat, forced a mass slaughter of affected cattle and sheep and resulted in an immediate, costly ban on all meat and meat-product exports from Britain.

Two years on, CSIRO researchers at the Australian Animal Health Laboratory in Geelong have led an international call for funds for a research project that will use biology's most advanced tools to develop an effective vaccine, and rapid new diagnostic tests, for FMD.

The ultimate aim, says AAHL director Dr Martyn Jeggo, is to eradicate the nemesis of the livestock industries from the planet. The human smallpox virus has already been eradicated, and a campaign is currently under way to eliminate rinderpest, another devastating disease of ruminant livestock species.

Jeggo says FMD is a global problem, and requires a global solution. FMD is rife in poorer nations in Africa, Asia and South America, which cannot afford to fund research, but the developed world cannot afford to sit back and do nothing.

Experts at AAHL have joined leading scientists from UK's Pirbright Laboratory, the US Plum Island Animal Disease Cetnre, and Canada's National Centre for Foreign Animal Disease (NCFAD) in calling for UN agencies and other donors to fund a A$90 million project to develop an effective vaccine and new, rapid diagnostics that would allow the disease to be detected early in the field, limiting its spread.

The funding sought for the project represents only 0.05 per cent of the estimated cost of the British epidemic.

Jeggo says that without an effective vaccine, millions of animals could be needlessly slaughtered, at a cost of billions of dollars to economies.

Current FMD vaccines generate only antibody-based immunity, which prevents the development of symptoms. But the the virus persists and multiplies in the infected animal's pharyngeal tissues; symptomless animals can spread the highly contagious virus to healthy animals, so huge numbers of healthu animals and infected animals must be slaughtered to prevent its spread.

Jeggo says vaccination is a realistic option for controlling an outbreak in a developed country like the UK.

NCFAD director Dr Paul Kitching says it is "almost inevitable" there will be future outbreaks of FMD in industrialised nations like the UK, Canada, the US and Australia.

Jeggo says the origin of the UK epidemic's source is a mystery, but FMD-contaminated imported meat is a likely source.

"Fifteen years ago we felt the existing vaccines were OK for vaccination, eradication and management," he says. "But then new outbreaks in places like South America made it clear that existing vaccines didn't do the job."

The problem, says Jeggo, was that previous peptide-based vaccines did not bring on cell-mediated immunity -- they induced an antibody attack on variable antigens on the surface of the virus. Because the virus mutates rapidly, it can stay ahead of the immune system's antibody defences by changing its exterior proteins.

In contrast, highly conserved structural proteins inside the virus provide a relatively fixed target for a vaccine, but they are inaccessible to antibodies.

But infected cells display these internal proteins on their surface, where they become 'visible' to cytotoxic T-cells, which destroy virus-infected cells.

Jeggo says the answer is to develop a polyvalent peptide vaccine that will induce T-cell immunity to different serotypes of the virus.

He says FMD could be more accurately described as seven diseases. Seven major serotypes of FMD historically have caused epidemics in Africa, Asia and South America, but the outbreaks of the past two decades -- including the recent British epidemic -- show that these geographically restricted serotypes are now spreading around the world.