Genetics and Genomic Regions Affecting Response to Newcastle Disease Virus Infection under Heat Stress in Layer Chickens

Abstract

Newcastle disease virus (NDV) is a highly contagious avian pathogen that poses a tremendous threat to poultry producers in endemic zones due to its epidemic potential. To investigate host genetic resistance to NDV while under the effects of heat stress, a genome-wide association study (GWAS) was performed on Hy-Line Brown layer chickens that were challenged with NDV while under high ambient temperature to identify regions associated with host viral titer, circulating anti-NDV antibody titer, and body weight change. A single nucleotide polymorphism (SNP) on chromosome 1 was associated with viral titer at two days post-infection (dpi), while 30 SNPs spanning a quantitative trait loci (QTL) on chromosome 24 were associated with viral titer at 6 dpi. Immune related genes, such as CAMK1d and CCDC3 on chromosome 1, associated with viral titer at 2 dpi, and TIRAP, ETS1, and KIRREL3, associated with viral titer at 6 dpi, were located in two QTL regions for viral titer that were identified in this study. This study identified genomic regions and candidate genes that are associated with response to NDV during heat stress in Hy-Line Brown layer chickens. Regions identified for viral titer on chromosome 1 and 24, at 2 and 6 dpi, respectively, included several genes that have key roles in regulating the immune response.

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

“…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. Data are being generated at a fast rate; new tools and types of analyses are needed to analyze the data in a more comprehensive way.…”

Association of Candidate Genes with Response to Heat and Newcastle Disease Virus

“…Estimates of heritability for traits that were measured in both groups are reported in Table 2 . The heritability estimate for viral load at 2 dpi for both groups (0.24 ± 0.06) was intermediate to separate estimates that were obtained from the NDV birds (0.32 ± 0.10) and the heat + NDV birds (0.17 ± 0.10) [ 35 , 36 ]. For 6 dpi, heritability for both groups was 0.09 (±0.04), while the estimates for the NDV and heat + NDV groups alone were not different from 0.…”

“…Body weights were recorded on days 0, 21, and 31 of age. Previously, two distinct genome wide association studies (GWAS) (NDV and heat + NDV) associated 600 k genotypes from these birds with the NDV viral load, anti-NDV antibody, and growth rate phenotypes described herein [ 35 , 36 ].…”

“…Heritabilities for anti-NDV antibody level at 10 dpi, ND viral load at 2 and 6 dpi, and pre and post NDV challenge growth rate were estimated across both treatment groups. Heritabilities for these NDV challenge related phenotypes were previously estimated for the treatment groups separately and were reported in [ 35 , 36 ]. For heat challenge related phenotypes, heritability was estimated among the heat challenged animals only [ 41 ].…”

“…Room and replicate were treated as distinct between treatments so that the RR effect captured treatment effects as well. Random effects included animal genetic effects (A) with a genomic relationship matrix that were computed using genotypes of 338,814 quality-controlled SNPs from the 600 K SNP panel [ 35 , 36 ] for 946 animals following the procedure described by [ 43 ], and residuals (e). The random effect of dam was included for pre-challenge measurements of growth rate.…”