Conserved, breed-dependent, and subline-dependent innate immune responses of Fayoumi and Leghorn chicken embryos to Newcastle disease virus infection

Abstract

Newcastle disease virus (NDV) is a threat to the global poultry industry, but particularly for smallholder farmers in low- and middle-income countries. Previous reports suggest that some breeds of chickens are less susceptible to NDV infection, however, the mechanisms contributing to this are unknown. We here examined the comparative transcriptional responses of innate immune genes to NDV infection in inbred sublines of the Fayoumi and Leghorn breeds known to differ in their relative susceptibility to infection as well as at the microchromosome bearing the major histocompatability complex (MHC) locus. The analysis identified a set of five core genes, Mx1 , IRF1 , IRF7 , STAT1 , and SOCS1 , that are up-regulated regardless of subline. Several genes were differentially expressed in a breed- or subline-dependent manner. The breed-dependent response involved TLR3 , NOS2 , LITAF , and IFIH1 in the Fayoumi versus IL8 , CAMP , and CCL4 in the Leghorn. Further analysis identified subline-dependent differences in the pro-inflammatory response within the Fayoumi breed that are likely influenced by the MHC. These results have identified conserved, breed-dependent, and subline-dependent innate immune responses to NDV infection in chickens, and provide a strong framework for the future characterization of the specific roles of genes and pathways that influence the susceptibility of chickens to NDV infection.

Novel Combined Tissue Transcriptome Analysis After Lentogenic Newcastle Disease Virus Challenge in Inbred Chicken Lines of Differential Resistance

“…The combined analysis of three target tissues generated a more extensive understanding of response to infection with lentogenic NDV at the whole organism level. Other studies have compared differences between the expression of key immune genes in these genetic lines after an NDV challenge in embryo (Schilling et al, 2018;Schilling et al, 2019) and at 3 weeks of age under heat stress conditions (Saelao et al, 2018). Also, genetic markers of interest have been identified in a commercial line (Rowland et al, 2018;Saelao et al, 2019) and African ecotypes (Walugembe et al, 2019) after infection with this same lentogenic strain.…”

Induction of Chicken Host Defense Peptides within Disease-Resistant and -Susceptible Lines

“…The Leghorn line Ghs6 was highly inbred from a cross of Leghorn lines; the Leghorn breed originated in Europe and provided the foundation stock for many commercial layer lines [ 28 , 29 , 30 ]. The Fayoumi line M15.2 was segregated from the Egyptian Fayoumi breed, has been highly inbred, and has large genetic distance from broiler and Leghorn lines [ 29 , 31 ].…”

“…The Fayoumi line M15.2 was segregated from the Egyptian Fayoumi breed, has been highly inbred, and has large genetic distance from broiler and Leghorn lines [ 29 , 31 ]. From past comparisons between inbred Fayoumi and Leghorn chickens, the Fayoumi line has shown more resistance against various pathogens and stressful environments, suggesting superior immune responses [ 29 , 30 , 32 , 33 ]. In previous studies, Fayoumis have been demonstrated to have different expression of several HDPs [ 34 ] and association of genetic variants with disease response [ 35 ].…”

Innate Immune Genes Associated With Newcastle Disease Virus Load in Chick Embryos From Inbred and Outbred Lines

“…We have previously described the use of the chick embryo, which becomes immunocompetent prior to hatch and in the protective environment of the shell, as a model to examine the innate immune response to NDV (Schilling et al, 2018, 2019). In one study, we found differential expression of innate immune genes from two highly inbred Fayoumi and Leghorn lines.…”