Road to Discovery: Genetic
Mapping Lays Groundwork for Cattle Disease Treatments
ARS scientists at the
National
Animal Disease Center's Bacterial Diseases of Livestock Research Unit in
Ames, Iowa, are producing maps that could one day lead researchers to discover
preventative and therapeutic treatments for several important cattle diseases.
For example, Mycobacterium
paratuberculosis, the bacterium that causes Johne's disease, was sequenced
in 2002 by Ames scientists under the direction of ARS microbiologist
John P.
Bannantine and Vivek Kapur, a researcher at the University of Minnesota's
Advanced Genetics Analysis Center.
The sequencing and discovery of several
genes will help differentiate the bacterium from other closely related
bacterial species and could help in the detection of the disease and
development of a vaccine.
Johne's disease, an intestinal disorder
characterized by diarrhea and weight loss in infected cattle, is found in 7
percent of beef herds and 22 percent of dairy herds in the United States.
Currently, it takes up to six months to identify the bacterium in laboratory
culture because M. paratuberculosis grows slowly, which hampers
diagnosis of the disease and the progress of scientific research
studies.
Bannantine and Kapur are also working to
identify antigens from the M. paratuberculosis genome and incorporate
the antigens into diagnostic tests so herds can be tested for infection.
 A few
years ago, ARS veterinarians
Ray
Waters and
Mitch
Palmer at Ames invented a new blood-based assay for detecting bovine
tuberculosis (TB) in animals. Bovine TB is caused by M. bovis, which is
genetically related to M. paratuberculosis. ARS has received a patent on
the test. Since the test only requires a single blood sample, animals are only
handled once. The assay works by
detecting
nitrite in blood-sample cultures because nitric oxide is produced by
mammals as a natural response when fighting TB. Although bovine TB is close to
being eradicated in the United States, it still poses a significant risk to
domestic livestock, wildlife and people worldwide.
Meanwhile, other ARS researchers at Ames
have either completed or are actively sequencing additional cattle pathogens.
ARS microbiologist
Shirley
Halling and Kapur led sequencing of Brucella abortus, a bacterium
that causes bovine brucellosis, a highly contagious bacterial disease that
induces late-term abortions and infertility in cows. They hope to identify
those genes that mediate protective immunity.
Also, ARS microbiologist
Richard
Zuerner is
leading
sequencing of the pathogen Leptospira borgpetersenii serovar hardjo,
the most common cause of leptospirosis in cattle, using an automated analyzer
operated by veterinary medical officer
David
Alt for rapid analysis of the organism's genes. Leptospirosis causes
abortions, stillbirths and weak offspring in cattle and swine. It can also
reduce milk production in cows.
These research projects are part of
Animal
Health, an ARS national program (#103) designed to conduct basic and
applied research on selected diseases of economic importance to the United
States livestock and poultry industries.
For more information, contact the unit's
acting research leader:
Mitch
Palmer, Ames, Iowa |
Research Briefs
An
electrostatic
system developed by ARS to reduce airborne dust and microorganisms in
poultry houses and hatcheries is being commercialized.
Bailey
W. Mitchell
(706) 546-3443
By creating a
genetic map of the
chicken, ARS researchers joined a Michigan State University biologist, who
created the barnyard animal's first physical map, in contributing to the
sequencing of chicken genes.
Hans H.
Cheng
(517) 337-6758
A new ARS database contains gene sequences that
will be used to pursue genomics-based control strategies to counter
major poultry
diseases.
Hyun S.
Lillehoj
(301) 504-8771
Too much protein for
lactating cows can
contribute to nitrogen pollution and, in some cases, decreased milk yield,
according to an ARS scientist.
Glen A.
Broderick
(608) 890-0053
A new ARS research center is focusing on meeting
the needs of forage-based
enterprises in the Mid-South.
James
R. Strickland
(859) 257-1647
An ARS researcher and her university colleagues
have found copper oxide wire particles effective in
de-worming sheep and
goats.
Joan M.
Burke
(479) 675-3834, ext. 227
Toxic rangeland plants
that weaken and kill livestock and wildlife are targeted by a new ARS lab in
Utah.
Lynn F.
James
(435) 752-2941
Young cloned pigs
might not fight diseases as effectively as non-cloned pigs, according to ARS
and university researchers.
Jeff
Carroll
(806) 746-5353
An ARS research has found that there may be a
direct correlation between
eggshell quality
and Salmonella infection in chickens.
Jean
Guard Bouldin
(706) 546-3446
Healthy Animals
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