Anaplasmosis to Viral Diarrhea--
A Look at ARS Vaccine Research
From the first whole-cell vaccine for hog
cholera in 1886 through the first effective subunit vaccine-- for
foot-and-mouth disease--created nearly a century later, USDA scientists have
long been at the forefront of vaccine research and development. Today,
Agricultural Research Service scientists at 12 locations are working on new or
improved vaccines for all major U.S. agricultural animals.
Although it is nearly always more desirable
to vaccinate and prevent diseases rather than treat existing ones, vaccine
development produces unique challenges. Scientists must learn the identity and
characteristics of the disease-causing agent (e.g. virus, bacterium), how the
agent stimulates an immune response in the animal host, and how the agent
avoids that response. The disease agent survives by overcoming the ongoing
evolutionary development of the animal as it attempts to resist disease. Some
of the larger viruses have even taken on genes from their host and modified
them to help evade an animals immune response.
Researchers at ARS laboratory on
Plum Island, for example, are working on two of
the worlds most difficult vaccine challenges: African swine fever and
The virus that causes African swine fever
has both direct and tickborne life cycles. It has a large, complicated genetic
structure with some genes similar to those that govern the hosts immune
response. Foot-and-mouth virus has 7 serotypes with at least 62 subtypes, each
requiring a specific vaccine. Similar to influenza viruses, foot-and-mouth
evolves rapidly to develop new ways of getting around vaccine strategies.
Social and political factors also enter into
vaccine development. In some cases, the disease may not be widespread enough to
make vaccine development and production cost-effective. In others, a vaccine
may make it difficult to determine whether an animal has naturally contracted
the disease of concern or merely received vaccine. Diagnostic complications can
have serious impacts on trade.
The key to overcoming these challenges is to
gain increasingly detailed knowledge about disease agents and the animals they
affect. During the last decade, researchers worldwide have shifted their focus
to understanding and manipulating specific proteins rather than entire disease
At ARS' National Animal Disease Center, for example,
scientists have been able to use biotechnology to remove virulence proteins
from the bacterium, Pasteurella haemolytica, which is involved in
causing shipping fever of calves. Injecting the modified P. haemolytica
into cattle induces an immune response and prevents the disease.
At the Southeastern Poultry Research Laboratory,
researchers have developed a vaccine using only the hemagglutinin protein from
avian influenza virus rather than the whole virus. These recombinant vaccines
provide excellent protection from avian influenza. These approaches will also
allow development of diagnostics tests to differentiate between vaccinated and
ARS is well-suited to conduct vaccine
research. Long-term projects allow scientists to spend the years necessary to
develop the best control strategies for each disease. And animal-care and
housing facilities allow researchers to better understand animal immune systems
by direct study.
Recent accomplishments include vaccines or
significant research progress on vaccines for brucellosis, mastitis, and
shipping fever in cattle; coccidiosis in chickens; and Streptococcus
iniae in fish and the first licensed modified live fish vaccine against
enteric septicemia of catfish.
Current research includes developing new or
improved vaccines for the following:
- Livestock: anaplasmosis, brucellosis,
bovine viral diarrhea, bovine leptospirosis, E. coli, foot- and-mouth
disease, porcine reproductive and respiratory syndrome (PRRS),
Salmonella, swine fever, and swine parasites.
Keith Murray, (515) 663-7200;
Daniel Rock, (631) 323-2500
- Poultry: avian influenza, avian leukosis
virus J, avian pneumovirus, coccidiosis, enteric viruses, fowl cholera,
Mareks disease, mycoplasmosis, Newscastle disease, Salmonella
enteridis, and turkey coryza.
David Swayne, (706) 546-3433
- Fish: Enterococcus and
Streptococcus in striped bass, Flexibacter columnaris infections
in tilapia and catfish, and parasitic diseases.
Phillip Klesius, (334)
For more information, contact the
researchers listed above or ARS National Program Staff:
William Laegreid ,
Caird Rexroad, Jr., (301) 504-7050
An ARS-produced clone of a pure-bred jersey cow
may offer genetic
resistance to mastitis. The cow, named "Annie," has genetically engineered
cells that secrete a protein called lysostaphin. In trials with transgenic
mice, lysostaphin killed mastitis-causing bacteria in mammary glands and
When fed to pigs and cows in low doses,
selectively killed Salmonella typhimurium and E. coli
O157:H7, ARS researchers found.
Oxbow lake fisheries can
be improvedby cultural practices established by ARS scientists. Plankton
growth, water quality and bass populations were all increased in two lakes
where best management practices were applied.
CD-ROM on screwworm
eradication, published by the National
Agricultural Library, presents the story of the sterile insect technique
and other technologies that made possible the pest's elimination from the
United States, Mexico and much of Central America.
Faster-growing catfish should result from
a new catfish breeding
line, released by ARS scientists.
These ARS researchers have been honored recently
for their achievements:
ARS Scientist of the Year
Koohmaraie , Meat Animal Research Center,
for innovative research to enhance meat quality and safety.
Aquatic Animal Health Research Laboratory, for
co-development of the first modified live vaccine licensed for fish in the
Animal Disease Research Unit, for discovery of
methods for detection and control of malignant catarrhal fever virus.
ARS Technology Transfer
Small Grains and Potato
Germplasm Research Unit, Aberdeen, Idaho, for developing a technique that
lowers the amount of phytate in grains, thereby improving the amount of
phosphorus that pigs, poultry and fish can absorb from feed.
Thomas Jenkins and
Meat Animal Research Center, for developing an
easy-to-use, science-based computer program that helps cattle producers make
breeding, feeding and management decisions for their herds.
A team of eight
researchers led by H. Duane
Norman, Animal Improvement Programs
Laboratory, for initiating a project that speeds up the rate of genetic
improvement of milk yield in dairy cows.