Host transcriptomic response to Newcastle disease virus in relatively resistant and susceptible inbred chicken lines

Newcastle disease virus (NDV) has devastating impacts on poultry throughout the world. The inbred Fayoumi and Leghorn chicken lines, previously characterized as relatively resistant and susceptible, respectively, to various pathogens were utilized to characterize host response to the NDV vaccine and identify potential genes and pathways associated with NDV resistance. Three-week-old chicks were inoculated with La Sota NDV (challenged) or PBS (nonchallenged) via the oculonasal route. At 2, 6, and 10 days post infection (dpi), approximately one-third of the birds within each line and challenge group were euthanized for tissue collection. At 2 and 6 dpi, lachrymal fluid was collected from all birds for viral quantification using qPCR. At 0 and 10 dpi, serum was collected from all birds to quantify NDV antibody levels using ELISA. The transcriptome response in tracheal epithelial cells, lungs, and Harderian glands from four birds per treatment group (line, dpi, and challenge group; 48 birds total) was analyzed using RNA-seq. These three tissues chosen for their location near the site of infection. A separate study analyzed mean survival time after challenge with velogenic NDV. These studies found the Fayoumi and Leghorn chickens were relatively resistant and susceptible, respectively to lentogenic and velogenic NDV, based on lachrymal fluid viral load, antibody levels, and within-tissue viral transcript counts detected by RNA-seq after the lentogenic challenge, and survival analysis after a velogenic challenge. The trachea, lung, and Harderian gland RNA-seq data were analyzed individually and jointly to gain a more comprehensive understanding of the impact of lentogenic NDV challenge using differential expression and co-expression analyses. The tissues with detectable viral transcripts, trachea and Harderian gland, activated T cell related pathways after challenge. The challenge had the largest impact on the trachea transcriptome, based on principal component analysis and numbers of differentially expressed genes. In the lung and Harderian gland, especially, the two lines had distinct responses to the virus. The combined tissue analysis revealed clusters of co-expressed genes that were correlated with important factors like line, challenge status, and dpi. Overall, EIF2 signaling, mTOR signaling, collagen related genes, and TNFSF13B / TNFRSF13B were identified as potential candidate genes and pathways related to NDV resistance. Further studies are required to determine and confirm how these genes and pathways impact NDV resistance

Transcriptome Analysis in Spleen Reveals Differential Regulation of Response to Newcastle Disease Virus in Two Chicken Lines.

Enhancing genetic resistance of chickens to Newcastle Disease Virus (NDV) provides a promising way to improve poultry health, and to alleviate poverty and food insecurity in developing countries. In this study, two inbred chicken lines with different responses to NDV, Fayoumi and Leghorn, were challenged with LaSota NDV strain at 21 days of age. Through transcriptome analysis, gene expression in spleen at 2 and 6 days post-inoculation was compared between NDV-infected and control groups, as well as between chicken lines. At a false discovery rate <0.05, Fayoumi chickens, which are relatively more resistant to NDV, showed fewer differentially expressed genes (DEGs) than Leghorn chickens. Several interferon-stimulated genes were identified as important DEGs regulating immune response to NDV in chicken. Pathways predicted by IPA analysis, such as "EIF-signaling", "actin cytoskeleton organization nitric oxide production" and "coagulation system" may contribute to resistance to NDV in Fayoumi chickens. The identified DEGs and predicted pathways may contribute to differential responses to NDV between the two chicken lines and provide potential targets for breeding chickens that are more resistant to NDV

More MHC-like Class I Y mRNA Detected in Relatively Resistant Fayoumis than Susceptible Leghorns

The inbred chicken lines Fayoumi and Leghorn have been shown to be relatively resistant and susceptible, respectively, to Newcastle disease virus (NDV). In this experiment we detected higher gene expression levels of MHC-like class I Y (MHCIY) in the Fayoumi trachea, lung, and Harderian gland of NDV challenged and nonchallenged birds across multiple time points. MHC region is important to the immune system and is often associated with resistance to pathogens. This gene may be associated with the Fayoumis’ resistant phenotype

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

Disease has large negative impacts on poultry production. A more comprehensive understanding of host–pathogen interaction can lead to new and improved strategies to maintain health. In particular, host genetic factors can lead to a more effective response to pathogens, hereafter termed resistance. Fayoumi and Leghorn chicken lines have demonstrated relative resistance and susceptibility, respectively, to the Newcastle disease virus (NDV) vaccine strain and many other pathogens. This biological model was used to better understand the host response to a vaccine strain of NDV across three tissues and time points, using RNA-seq. Analyzing the Harderian gland, trachea, and lung tissues together using weighted gene co-expression network analysis (WGCNA) identified important genes that were co-expressed and associated with parameters including: genetic line, days post-infection (dpi), challenge status, sex, and tissue. Pathways and driver genes, such as EIF2AK2, MPEG1, and TNFSF13B, associated with challenge status, dpi, and genetic line were of particular interest as candidates for disease resistance. Overall, by jointly analyzing the three tissues, this study identified genes and gene networks that led to a more comprehensive understanding of the whole animal response to lentogenic NDV than that obtained by analyzing the tissues individually

Transcriptional Innate Immune Response of the Developing Chicken Embryo to Newcastle Disease Virus Infection

Traditional approaches to assess the immune response of chickens to infection are through animal trials, which are expensive, require enhanced biosecurity, compromise welfare, and are frequently influenced by confounding variables. Since the chicken embryo becomes immunocompetent prior to hatch, we here characterized the transcriptional response of selected innate immune genes to Newcastle disease virus (NDV) infection in chicken embryos at days 10, 14, and 18 of embryonic development. The results suggest that the innate immune response 72 h after challenge of 18-day chicken embryo is both consistent and robust. The expression of CCL5, Mx1, and TLR3 in lung tissues of NDV challenged chicken embryos from the outbred Kuroiler and Tanzanian local ecotype lines showed that their expression was several orders of magnitude higher in the Kuroiler than in the local ecotypes. Next, the expression patterns of three additional innate-immunity related genes, IL-8, IRF-1, and STAT1, were examined in the highly congenic Fayoumi (M5.1 and M15.2) and Leghorn (Ghs6 and Ghs13) sublines that differ only at the microchromosome bearing the major histocompatibility locus. The results show that the Ghs13 Leghorn subline had a consistently higher expression of all genes except IL-8 and expression seemed to be subline-dependent rather than breed-dependent, suggesting that the innate immune response of chicken embryos to NDV infection may be genetically controlled by the MHC-locus. Taken together, the results suggest that the chicken embryo may represent a promising model to studying the patterns and sources of variation of the avian innate immune response to infection with NDV and related pathogens

Host transcriptomic response to Newcastle disease virus in relatively resistant and susceptible inbred chicken lines

Newcastle disease virus (NDV) has devastating impacts on poultry throughout the world. The inbred Fayoumi and Leghorn chicken lines, previously characterized as relatively resistant and susceptible, respectively, to various pathogens were utilized to characterize host response to the NDV vaccine and identify potential genes and pathways associated with NDV resistance. Three-week-old chicks were inoculated with La Sota NDV (challenged) or PBS (nonchallenged) via the oculonasal route. At 2, 6, and 10 days post infection (dpi), approximately one-third of the birds within each line and challenge group were euthanized for tissue collection. At 2 and 6 dpi, lachrymal fluid was collected from all birds for viral quantification using qPCR. At 0 and 10 dpi, serum was collected from all birds to quantify NDV antibody levels using ELISA. The transcriptome response in tracheal epithelial cells, lungs, and Harderian glands from four birds per treatment group (line, dpi, and challenge group; 48 birds total) was analyzed using RNA-seq. These three tissues chosen for their location near the site of infection. A separate study analyzed mean survival time after challenge with velogenic NDV. These studies found the Fayoumi and Leghorn chickens were relatively resistant and susceptible, respectively to lentogenic and velogenic NDV, based on lachrymal fluid viral load, antibody levels, and within-tissue viral transcript counts detected by RNA-seq after the lentogenic challenge, and survival analysis after a velogenic challenge. The trachea, lung, and Harderian gland RNA-seq data were analyzed individually and jointly to gain a more comprehensive understanding of the impact of lentogenic NDV challenge using differential expression and co-expression analyses. The tissues with detectable viral transcripts, trachea and Harderian gland, activated T cell related pathways after challenge. The challenge had the largest impact on the trachea transcriptome, based on principal component analysis and numbers of differentially expressed genes. In the lung and Harderian gland, especially, the two lines had distinct responses to the virus. The combined tissue analysis revealed clusters of co-expressed genes that were correlated with important factors like line, challenge status, and dpi. Overall, EIF2 signaling, mTOR signaling, collagen related genes, and TNFSF13B / TNFRSF13B were identified as potential candidate genes and pathways related to NDV resistance. Further studies are required to determine and confirm how these genes and pathways impact NDV resistance.</p