DATE=3/14/01

TYPE=AGRICULTURE TODAY #2148

NUMBER=7-34614

TITLE=New Vaccines for Foot and Mouth Disease

BYLINE=ROB SIVAK

TELEPHONE=202-619-2023

DATELINE=WASHINGTON

EDITOR=SMART

CONTENT=

INTRO:Scientists at a U-S government laboratory are working on new vaccines against Foot and Mouth Disease that might someday prevent epidemics like the one now decimating Britain's livestock industry. VOA's Rob Sivak reports:

TEXT:There are vaccines today, made from killed or weakened Foot and Mouth Disease viruses, that provide livestock some protection against this extremely infectious disease. But experts say current vaccines are difficult to administer, offer livestock only short-term immunity, and can mask the spread of the disease from herd to herd.

Work on more powerful and longer-lasting vaccines is underway at the U-S Agriculture Department's Plum Island Animal Disease Center, a unique laboratory three kilometers off the tip of Long Island, on New York's Atlantic Coast. It's the only lab in the country sufficiently secure and isolated to safely study the dreaded virus. Peter Mason directs the Foot and Mouth Disease research team at Plum Island:

DALET:CUT ONE MASON

"We are developing several new types of genetically engineered vaccines, and these include vaccines where you just take D-N-A molecules from the virus, and inoculate them into animals. Those D-N-A molecules which have genetic information but which are not toxic to the animals, will cause the animals to produce proteins that are the same as the proteins the virus produces. As a result of producing these foreign proteins in the animals, the animals develop the immune response they need to control the disease."

TEXT:An alternative and equally promising approach involves using fragments of D-N-A material from the Foot and Mouth Disease virus and inserting them into other, non-harmful viruses. When injected into healthy animals, these modified carrier viruses can trigger immunities not only to Foot and Mouth Disease but to a range of other diseases as well.

Plum Island researcher Peter Mason says both gene-altered vaccines would be ideal for containing major outbreaks like Britain's, because they would build immunity quickly and safely among animals near an infected site. He adds that the unique biochemical signatures of the new vaccines would also solve a serious problem with today's killed-virus and weakened-virus vaccines blood tests cannot now distinguish healthy, vaccinated animals from those with active Foot and Mouth Disease infections:

DALET CUT TWO MASON

"The vaccinated animal, you could market the meat. The infected animal you would never want to market the meat because of the possibility of transmission of the agent to other animals. So this becomes quite an important problem when you start to discuss how many animals need to be eradicated around an outbreak. That's a significant concern from the standpoint of both direct economic loss, public perceptions of these large trenches where they are running animals into or burning animals, and thirdly, animal welfare concerns. We don't want to be destroying animals and disposing of large amounts of animal protein that can be used."

TEXT:Peter Mason says that while tests with the new gene-altered vaccines have been encouraging, their use in the field could be several years away not soon enough to save Britain's livestock industry. Even if the vaccines prove effective, Mister Mason believes it is unlikely that Foot and Mouth Disease will ever be vaccinated out of existence. The virus, he says, is too changeable and too widespread for that:

DALET CUT THREE MASON

"For example, in Africa, where the virus probably originated, there are wildlife species that are susceptible to the virus and they maintain the virus in nature. So there will be a chronic problem in areas where wildlife and domestic animals overlap, in that there will be transmission to domestic animals. So in Africa we will not be able to eradicate F-M-D."

TEXT:And Mister Mason adds that successful prevention of Foot and Mouth Disease can never rely solely on vaccines:

DALET:CUT FOUR MASON

"It is a question of economics, of good infrastructure in your department of agriculture, being able to get out there, identify disease, and then enforce vaccination strategies."

TEXT:American scientist Peter Mason directs research on new Foot and Mouth vaccines at the U-S Department of Agriculture's Animal Disease Center on Plum Island, New York. I'm Rob Sivak.

Neb/rms/nes