UC Davis

Background

Newcastle disease virus (NDV) is a threat to poultry production worldwide. A better understanding of mechanisms of resistance and susceptibility to this virus will improve measures for NDV prevention and control. Males and females from resistant Fayoumi and susceptible Leghorn lines were either challenged with a lentogenic strain of the virus or given a mock infection at 3 weeks of age. The lung transcriptomes generated by RNA-seq were studied using contrasts across the challenged and nonchallenged birds, the two lines, and three time points post-infection, and by using Weighted Gene Co-expression Network Analysis (WGNCA).

Results

Genetic line and sex had a large impact on the lung transcriptome. When contrasting the challenged and nonchallenged birds, few differentially expressed genes (DEG) were identified within each line at 2, 6, and 10 days post infection (dpi), except for the more resistant Fayoumi line at 10 dpi, for which several pathways were activated and inhibited at this time. The interaction of challenge and line at 10 dpi significantly impacted 131 genes (False Discovery Rate (FDR) <0.05), one of which was PPIB. Many DEG were identified between the Fayoumi and Leghorns. The number of DEG between the two lines in the challenged birds decreased over time, but increased over time in the nonchallenged birds. The nonchallenged Fayoumis at 10 dpi showed enrichment of immune type cells when compared to 2 dpi, suggesting important immune related development at this age. These changes between 10 and 2 dpi were not identified in the challenged Fayoumis. The energy allocated to host defense may have interrupted normal lung development. WGCNA identified important modules and driver genes within those modules that were associated with traits of interest, several of which had no known associated function.

Conclusions

The lines' unique response to NDV offers insights into the potential means of their resistance and susceptibility. The lung transcriptome shows a unique response to lentogenic NDV compared to a previous study on the trachea of the same birds. It is important to analyze multiple tissues in order to best understand the chicken's overall response to NDV challenge and improve strategies to combat this devastating disease.