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Contributed Papers: Oral Presentations Immunology |
Development of future strategies for vaccinating chickens
against coccidiosis using recombinant antibodies,
genes and peptides.
Lillehoj, H. S., Dalloul, R. A., and
Park, D.W. Animal Parasitic Diseases Laboratory, Animal
and Natural Resources Institute, U.S. Department of
Agriculture, Beltsville, MD. 20705, (email address
of presenting author: hlilleho@anri.barc.usda.gov
)
Avian coccidiosis is caused
by several different species of the intestinal protozoan
parasites, Eimeria. Ability to develop novel control
strategies against coccidiosis will reduce major economic
losses to the poultry industry worldwide. Using functional
genomics and molecular biology tools, we have now
better understanding of host innate and acquired immunity
to Eimeria. This paper will discuss various new strategies
that we have taken to induce protective immunity to
avian coccidiosis. Furthermore, novel vaccine delivery
technologies are being applied to poultry to induce
protective immunity against coccidioisis using recombinant
proteins, genes and immunomodulators. For example,
we have demonstrated that recombinant coccidian protein
or recombinant DNA carrying a coccidian gene, when
injected either into 18-day-old embryos using a commercial
in ovo injector, Intelliject, or injected intramuscularly
using a gene gun, reduced oocyst shedding and enhanced
body weight gain. Addition of chicken cytokines or
CpG oligodinucleotides further enhanced the vaccine-induced
protection against coccidiosis. These results indicated
that the type and dose of DNA vaccine and adjuvant
influence the quality of the local immune response
to DNA vaccination against coccidiosis. Another method
that we are developing utilize recombinant antibodies
whose specificities are directed against apical complex
proteins involved in host cell invasion. Recombinant
antibodies directed against apical complex antigen
of Eimeria blocked sporozoite invasion of host cells
and reduced oocyst shedding when injected in ovo at
18-day of embryonic development. Taken together, we
have demonstrated how new generation vaccines and
immunomodulators could be used to enhance host resistance
against avian coccidiosis.
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