Research in this area is aimed at combating illness and improving production in poultry by focusing on developing diagnostics, improving vaccines, discovering new and emerging pathogens, and learning what mechanisms dictate growth. In looking at disease, researchers are examining host-pathogen interactions, immune mechanisms, immune system development, innate disease resistance, immune suppression, viral persistence, oncogenesis and interactions among disease agents. They are tackling problems in poultry with combined conventional and molecular approaches and using poultry genomics to uncover new genes that may enhance health, growth and performance in this vital area of the food supply.
A primary focus of this work is Marek’s disease, the most serious infectious disease affecting the $11 billion global poultry industry. This herpesvirus-induced lymphoma causes tumors in poultry at a cost of $1 billion annually to producers. Although most chickens are inoculated against the illness at or before hatch, Marek’s disease continually mutates and becomes more virulent, countering the current vaccines and imperiling the industry.
Dr. Robin Morgan, principal researcher and Dean of the University of Delaware’s College of Agriculture and Natural Resources, leads a team of scientists who are striving to understand how the Marek’s disease virus alters T lymphocytes white blood cells in infected chickens. Dr. Morgan’s group tackles three major areas in studying the disease and its cure: The functions of viral gene products important in causing the malignant tumors of Marek’s disease; latency and reactivation of the virus; and critical virus-host cell interactions that influence the development of these tumors and immunity against them. With their partners in industry, Dr. Morgan’s group is helping to develop next-generation vaccines that will ensure the freedom from the disease.
In recent months, Dr. Morgan’s laboratory has concentrated on mutants of the virus that lack the latency-associated transcripts. Dr. Morgan has described a family of latency-associated transcripts expressed in tumors and lymphoblastoid cells derived from them. Current studies look at the relationship between splicing patterns and possible transcript functions. Latency is being compared among strains that differ in virulence. The team uses microarray technology to investigate host-virus cell interactions and they have been responsible for identifying host cell genes induced upon Marek’s disease virus infection.
Along with her colleague, Dr. Joan Burnside, a professor of animal and food science at the University, Dr. Morgan is also analyzing the avian genome, identifying DNA sequences that represent genes expressed in chicken tissue. Dr. Burnside has taken advantage of high-throughput DNA sequencing available through the Institute to build a publicly available chicken expressed sequence tag (EST) database that can be used in microarrays to profile immune system development. By analyzing changes in these profiles, researchers hope to be able to maximize immune responsiveness of chickens. Arrays are also used to identify possible disease resistance genes.
Dr. Burnside's lab also looks at growth hormone regulation in poultry and is credited with identifying and characterizing the hormone’s receptor gene. Mutations of this gene in sex-linked dwarf chickens have been found. Researchers are using the dwarf chicken as an experimental model in the study of this growth hormone receptor.
Funding for this research comes from the U.S. Department of Agriculture, Intervet International and the State of Delaware.