The long view: a bright past, a brighter future? Forty years of chicken immunology pre- and post-genome.

The chicken, being a non-mammal, has perhaps surprisingly made many seminal contributions towards our understanding of immune responses in all species. Despite this, pre-genome our ability to study immune responses in detail in birds was limited both in terms of reagents and also in our understanding of the immune gene repertoire in birds. Post-genome things have radically changed, although there are still gaps, both in the genome sequence and in the repertoire, the latter not conclusive until the genome is complete. We now know that for many immune gene families (e.g. the major histocompatibility complex, the tumour necrosis factor superfamily and the tumour necrosis factor receptor superfamily, the chemokines, the interleukin-1 family) the chicken repertoire is smaller, although there are interesting/confusing examples (e.g. the chicken immunoglobulin-like receptors family) where the chicken repertoire is greater than that of mammals. The future for chicken immunology is exciting, and in particular we have the potential to develop novel solutions for disease (such as novel vaccines or breeding for disease resistance) based on our improving knowledge of the chicken's immune response to disease.