New Antibody "Handcuffs" Mastitis BacteriaBy
A high-tech molecule called a bifunctional antibody may give cows a natural
way to fight mastitis, an infection of the mammary gland. The antibody "handcuffs"
the mastitis bacterium to a white blood cell, which then zaps the pathogen with
Mastitis costs the U.S. dairy industry more than $2 billion annually. A
producer with 100 cows can expect 50 to 80 cases of mastitis each year.
Antibiotics are often ineffective. Producers can't sell milk from treated cows
for a few days. Cows that don't respond may be sold for meat, increasing the
chance of antibiotic-contaminated beef.
To find a more natural alternative, dairy scientist Max Paape has turned to
bifunctional, or coupled, antibodies. These are proving effective against human
cancers in early clinical trials. Paape is with the
Agricultural Research Service in
Beltsville, Md. To produce the first bifunctional antibody for farm animals, he
enlisted help from French researchers at the National Institute for Agronomic
Research, Nouzilly, France, and David Segal of the National Cancer Institute,
One end of the bifunctional antibody hooks to a mastitis-causing bacterium,Staphylcoccus
aureus. The other end snags its "terminator," a neutrophil--a
specialized white blood cell from the cow's immune system. This triggers the
neutrophil to release a lethal spray of hydrogen peroxide. The spray can't miss,
since neutrophil and bacterium are "handcuffed" by the antibody.
It could take several years to ready the technology for farmers. Scientists
must first prove bifunctional antibodies can adequately boost the killing power
of the cow's neutrophils. Then they will have to refine the technology for its
most effective use. Still, Paape envisions a battery of bifunctionals for a
range of pathogens in a variety of farm animals.
An article about the research appears in the June issue of Agricultural
Research magazine. The article also is on the World Wide Web at:
Scientific contact: Max Paape,
Disease Resistance Laboratory, Beltsville Agricultural Research Center,
Bldg. 173, Beltsville, MD 20705-2350, phone (301) 504-8302, fax (301) 504-9498,