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

Abstract

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.

Genetic responses of inbred chicken lines illustrate importance of eIF2 family and immune-related genes in resistance to Newcastle disease virus

“…Evaluation of the transcriptome of these two genetically distinct lines also suggests that NDV infection may cause upregulation of different genes in a line-dependent manner 19 . These results were also observed in the spleen, where few interferon stimulated genes were upregulated by NDV challenge 21 .…”

“…This RNase L-dependent pathway is best characterized; however, recent studies have described OAS antiviral activity through a RNase L-independent pathway 35,36 . In chickens, OAS has been shown to be encoded by only one gene (OASL) 37 and to be upregulated after infection with different viruses 38,39 including NDV 3,4,21 . The role of OASL in the control of NDV replication was confirmed in vitro 8 , as the overexpression of OASL reduced the replication of NDV and the absence of OASL significantly enhanced viral replication.…”

“…Upregulated expression of the OASL gene was also observed in challenged Fayoumi and Leghorn in our previous study using RNAseq. 21 . Besides the function described above, OAS also is related to programed cell death 40 .…”

“…At 21 days of age, half of the chickens were inoculated with 200 µl of 10 7 EID 50 of La Sota NDV (NDV challenged group, n = 49) through nasal and ocular inoculation routes. The other chickens received 200 µl of phosphate-buffered saline (PBS) (nonchallenged group, n = 40) through same conditions, as described in [19][20][21] . The chickens from both lines and challenge statuses (NDV challenged or nonchallenged) were euthanized with sodium pentobarbital solution at 2 or 6 dpi.…”

“…Samples were collected from spleen and placed into RNAlater solution (ThermoFisher Scientifc, Waltham, MA) and stored in a −80 °C freezer until the RNA isolation procedure. The samples used for gene expression analysis in the current study were previously used by 21 . The detailed description for the experimental design and animal activities can be found in 20 .…”