Deciphering desirable immune responses from disease models with resistant and susceptible chickens

Authors: BROOM, LEON - University Of Leeds; Kogut, Michael - Mike

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2018
Publication Date: 4/1/2019
Citation: Broom, L.J., Kogut, M.H. 2019. Deciphering desirable immune responses from disease models with resistant and susceptible chickens. Poultry Science. 98(4):1634-1642. https://doi.org/10.3382/ps/pey535.
DOI: https://doi.org/10.3382/ps/pey535

Interpretive Summary: During the first week of life after hatching, the immune system of the chick is not very good at fighting bacterial infections such as Salmonella and other germs. We do not know the reason for this problem. However, there are chemicals in the body of chicks called cytokines. These chemicals control the way chicks fight infections. The objective of this experiment was to look at cells of the chick and determine whether the cells’ internal machinery can produce these chemical reactions or not. We found that the heterophils do produce some of these chemicals when they come in contact with Salmonella and other germs. However, some of these chemicals are not produced, which can cause a problem in chicks when infected with different germs. The results of this experiment are important to the pharmaceutical industry in the United States because we now know which chemicals are produced (or not) by the chick’s immune cells when they encounter Salmonella and other germs. Thus, we can now determine if there are ways for us to get the chick to make these chemicals to help it fight Salmonella infections.

Technical Abstract: Coccidiosis and necrotic enteritis (NE) are among the most significant diseases affecting the poultry industry. These diseases have become more prominent in the wake of policies to reduce the use of antibiotics in animal production. This has led to more research focused on better understanding the immune system and its responses to pathogen challenge, and thus developing informed strategies to exploit immune responses that can support enhanced disease resistance and growth performance. Some chicken breeds and lines show greater resistance or susceptibility to various diseases and, thus, these birds may be able to shed light on immune processes or pathways that contribute to the more resistant/susceptible state. This review attempts to identify potentially important genes that show some consistency in (relative) up or downregulation in key tissues between the resistant and susceptible chickens. For coccidiosis and NE, relative downregulation of IL-10 and (slightly less consistently) upregulation of IFN-gamma appear to be features of more resistant birds. Data for IFN-alpha, IL-12, and IL-17D are currently less consistent. Gene expression data from NE studies have identified some potentially interesting, perhaps less well understood, immune-related genes (e.g. TCF12, BCL2, IRF2, TRAF3, TAB3, etc.,) that may be associated with the resistant and/or susceptible phenotype. Salmonella and Campylobacter are important foodborne pathogens harboured by the chicken intestinal tract, while infectious bursal disease and infectious bronchitis are also important viral diseases of poultry. We, therefore, consider whether there are consistent features from resistant/susceptible disease models with these pathogens that relate to findings from the coccidiosis and NE studies. It is not anticipated that ideal immune responses to these pathogens will be identical, but rather that consistent elements may be identified that could help inform breeding or alternative strategies to support general disease resistance and enhanced (and efficient) flock productivity.