Chicken genome used to develop new poultry vaccine
US researchers are now making use of a chicken genome
sequence to develop vaccines to fight Marek's disease, which costs the poultry
industry US$1 bln a year worldwide.
AG Professional reports that researchers in Michigan, Delaware and Texas
will be involved in this development project, which is being funded by USDA's
Cooperative State Research, Education, and Extension Service.
Jerry Dodgson and colleagues at Michigan State University, the
USDA-Agricultural Research Service Avian Disease and Oncology Lab, the
University of Delaware and Texas A&M University began by assembling the
physical map of the chicken genome using DNA clones that describe all or nearly
all of the genes in the chicken.
The researchers then began to identify individual genes whose levels went
up or down after infection by Marek's disease virus (MDV)
. To do so, they used a 'gene chip'
with approx. 13,000 gene sequences (about half the chicken genes) to assay
levels of gene products before and after MDV infection, and in chicken lines
that were highly susceptible versus lines that were more resistant.
Distinguish infected and uninfected cells
MDV spreads via inhaled feather dander. So, infected tissue is a mixture of
uninfected and infected cells, making it difficult to distinguish differences
between them. Using a laser to micro-dissect a clump of infected cells from
uninfected ones, the group discovered a suite of genes in the chicken genome
that influence the course of viral infection. This new understanding of the
interaction between the virus and the genes was used to develop new ways to
identify genes in the chicken that are turned on or modified by MDV infection.
Through this research, a new recombinant vaccine was developed by cloning
one of the identified genes, called chicken MIP-1, into the vaccine strain of
the virus. The protection this vaccine provides is comparable to that afforded
by the best commercially available vaccines.
The chicken genome sequence developed during this project is now available
to scientists working on MDV worldwide.
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