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A new brucellosis vaccine, called RB51, lets veterinarians tell the
difference between livestock that have been vaccinated and those that have
been infected naturally. This vaccine is missing a part of
Brucella abortus, the bacterium behind brucellosis. Result: The
immune system of animals receiving the new vaccine doesn't produce the
same antibodies as naturally infected animals. Developed by a Virginia
Polytechnic Institute researcher and tested by ARS scientists and Colorado
Serum Co. in Denver, the vaccine worked well in tests with cattle.
Brucellosis costs the U.S. cattle industry an estimated $30 million
annually. Current commercial vaccines are effective, but stimulate the
animal's immune system to produce the same antibodies as natural
infection, making it impossible to sort out vaccinated from infected
animals. Brucellosis causes abortion and reduced milk production in
cattle, sheep and goats.
Brucellosis Research, Ames, IA
Mark G. Stevens, (515) 239-8313
New, genetically engineered plum plants resist the devastating plum pox
virus, thanks to five years of research to protect U.S. fruit growers from
this deadly disease. Plum pox virus has not been found in North
America, but is rampant throughout European orchards and was recently
discovered in South America. There is no known control for the virus,
which attacks plums, apricots and peaches and is spread by aphids and
grafting. To create the transgenic plants, ARS scientists injected
healthy plum plants with a gene from the coat protein surrounding the
virus. After two years of tests, one breeding line appears to have
complete immunity to the virus. USDA's Animal and Plant Health Inspection
Service collaborated on the research.
Appalachian Fruit Research
Station, Kearneysville, WV
Ralph Scorza, (304) 725-3451
A damaging virus that infects grape germplasm can now be detected in
two days instead of the usual three or four years. The technique
detects strains 3 and 4 of the grapevine leafroll virus if it's hiding in
grape vine cuttings imported from other countries. Now, to make sure
these imported cuttings are virus-free, scientists must grow them in
quarantine for three to four years. It takes that long for visible signs
of the virus to appear on vine leaves. This creates a bottleneck for
scientists who want to see if the foreign germplasm contains genetic
resistance for disease, insects and other traits, or shows superior
performance in current or potential grape production areas in the United
States. The new test, developed by ARS and Cornell University
researchers, eases the logjam by giving scientists a quick way to detect
grapevines infected with the virus. Tests for other grape viruses are
being developed.
Plant Genetic Resources, Geneva, NY
Philip L. Forsline, (315) 787-2390
DNA fingerprinting can be used to differentiate between strains of a
Jekyll and Hyde fungus that's a pest of vegetables and fruits. If a
destructive strain is identified, steps can be taken to control it.
Usually the fungus, Phomopsis, is dormant and harmless. But under the
right conditions--often unknowingly created by humans--some strains can
become a devastating plant pathogen. One such outbreak, from 1989 to
1991, resulted in Phomopsis-related losses in U.S. soybeans alone totaling
over $500 million. The fungus is tough to combat because, its simple form
and structure have masked clues to understanding which strains may become
active. ARS experts examined DNA fingerprinting of 43 strains of the
fungus from a wide variety of plants from North America and the Caribbean.
They discovered some nasty strains have an extremely broad host
range--contrary to the belief the fungus attacked only specific crops. As
a result of the research, the DNA work will help plant quarantine
officials at ports of entry keep the fungus from entering the country.
Systematic Botany and Mycology
Laboratory, Beltsville, MD
Amy Rossman/Steve Rehner, (301) 504-5364
Last updated: October 28, 1996
Return to: Quarterly Report
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