A chicken genome
map is guiding development of the first genetically engineered Mareks
disease vaccine. Young birds are the most susceptible. The next step will be
breeding resistant chicks. Click the image for more information about
Michigan Lab on Path to New Marek's Disease
Vaccine By Don
Comis July 27, 2006
Experimental versions of the first genetically engineered Marek's
disease vaccine for poultry are being developed by Agricultural Research
Service (ARS) scientists in Michigan.
Scientists at the ARS Avian Disease and Oncology Laboratory (ADOL)
at East Lansing, Mich., led by ARS veterinary medical officer
Fadly, are testing the vaccines with an eye toward producing the
next-generation vaccine against Marek's disease. These recombinant DNA vaccines
should provide protection longer than previous versions of the vaccine,
possibly buying the time needed to breed the first generation of
Marek's-resistant chickens, using other modern genetic techniques.
Since the lab's founding in the 1930s, scientists there have held the
tumor-causing Marek's disease in check. In 1972, ARS veterinary medical officer
L. Witternow retired, but still collaborating at East
Lansingand colleagues developed the first vaccine against Marek's, as
well as several updates as the disease evolved. It's still a major threat to
the poultry industry, because new strains continue to emerge to challenge the
The lab was formed during an epidemic of what was then called avian
"leucosis complex," which was later found to comprise Marek's, avian leucosis
virus and other viral diseases. The small team of ADOL scientists has fought
ever since to stay at least one step ahead of those and other emerging chicken
The researchers are also breeding chickens resistant to Marek's and
other diseases, using the chicken genome map and other genetic tools. ADOL
scientists helped map the chicken's genomethe first barnyard animal to
have its genes mapped.
They also rely on 19 lines of chickens bred specially to make
identification of disease-resistance genes easier. These are the latest
addition to a collection of more than 50 inbred lines of chickens in a unique
gene pool maintained since the 1930s in live chickens that are carefully
quarantined and protected.
The world's six major chicken breeder farms count on ARS to keep them
from being wiped out by an epidemic of Marek's or other viral disease.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.