All animals and humans have a set of genes called the major histocompatibility complex (MHC) that plays an important role in the immune system.

Within the MHC is a smaller set of genes MHC class II genes that are directly involved with cell-to-cell communication. This communication spreads the word about invading diseases, rallying the immune system to mount a defense.

"There are about a half-dozen MHC class II genes in chickens, but we've found only one or two that function," said Susan Lamont, professor of animal science. "If more genes can be activated, it would provide chickens with better capabilities to defend against disease."

Lamont also has found that MHC class II genes are not activated in all cells of the poultry immune system. "We want to know why they are restricted to only certain kinds of cells," she said.

Lamont and Susan Carpenter, a researcher in ISU's College of Veterinary Medicine, are trying to find out what limits the activation of disease-protecting genes in chickens, while gaining basic understanding on how the genes are regulated.

In lab experiments, they are inserting the MHC class II genes into a wide variety of immune-system cells. "We want to see whether the genes can be 'turned on' in cells where they normally wouldn't be activated," Lamont said. "If they do work in other kinds of cells, we may eventually be able to produce chickens that are better protected from disease."

Using tissue culture experiments, they have been studying naturally occurring compounds that can increase the activity of MHC class II genes. "This may be one approach to increasing chickens' disease resistance, especially to viral diseases," Lamont said. "These compounds may provide a booster effect that makes vaccines more effective."

Besides shedding light into how the genes function, Lamont said she hopes the research will lead to improved disease resistance and production efficiency in poultry. "It may help breeders identify birds with naturally high levels of this kind of gene activity. We also may use naturally occurring compounds to increase gene expression levels. Or, we could use genetic engineering to produce chickens with better disease resistance."

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