Gene May Help
Prevent Mastitis in Dairy Cows
By Rosalie Marion
August 6, 2002
Agricultural Research Service scientists
have filed a patent application on a cloned gene that promises to treat or
prevent bacterial infections that cause mastitis in dairy cows. The gene
produces a protein that is naturally present in cows' milk and blood plasma,
but in amounts too small to have any therapeutic effect. The recombinant
protein, named CD14, binds to and neutralizes toxins made by bacteria that
Each year, about 3 million U.S. dairy cows develop acute mastitis after
infection with coliform bacteria that lurk in the cleanest of barns. The
microbes infiltrate dairy cows' udders, putting about one-tenth of infected
cows out of commission. The problem costs dairy farmers an estimated $1.4
billion annually from incapacitated cows and milk that can't be sold.
ARS' Max Paape, a dairy scientist, and Dante Zarlenga, a molecular
biologist, along with cell biologist Yan Wang, now with the
National Institute of Allergy
and Infectious Diseases in Rockville, Md., cloned the gene and demonstrated
the effectiveness of the protein against mastitis infections. Paape and
Zarlenga are in the ARS
Immunology and Disease Resistance Laboratory in Beltsville, Md.
CD14 sensitizes the lining of a cow's mammary glands to the very low levels
of the bacterial toxin, called endotoxin, that are produced in the early stages
of an infection. Once sensitized, these mammary cells recruit white blood cells
that attack and kill infiltrating bacteria before they can establish an
Scientists now are conducting tests to support the new hypothesis that cows
genetically engineered to produce higher-than-normal amounts of CD14 could
enjoy CD14's protection from infection as well.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.