Structural Homologies of Major Immune-related Genes between Duck and Chicken: Implications on Differential Avian Resistance Against Influenza Virus

Avian influenza (Al) is a highly contagious viral disease in birds. The innate immune system serves as a first line of defense against invading pathogens including avian influenza viruses. It senses and defends against microbial molecules by the so-called pattern-recognition receptors (PRRs), including toll-like receptors (TLRs), nucleotide-oligomerization domain (NOD)-like receptors and retinoic acid-inducible gene l(RIG-I)-like receptors(RLRs), and other immune response elements, such as major histocompatibility complex (MHC), Mx and cytokine, etc. Ducks and chickens are among the most important hosts in the maintenance and transmission cycles of influenza A viruses, but ducks are more resistant to avian influenza than chickens, which is thought to be related to innate immune response genes. A comparison of the genetic makeup between these two close genetic model organisms could provide important insights into the molecular basis for this difference in susceptibility. The review summarizes the structural and functional differences of major immune-related genes between duck and chicken.