Integrated transcriptome and histone modification analysis reveals NDV infection under heat stress affects bursa development and proliferation in susceptible chicken line

Authors: CHANTHAVIXAY, GANREA - University Of California, Davis; KERN, COLIN - University Of California, Davis; WANG, YING - University Of California, Davis; Saelao, Perot; LAMONT, SUSAN - Iowa State University; GALLARDO, RODRIGO - University Of California, Davis; RINCON, GONZALO - Zoetis; ZHOU, HUAIJUN - University Of California, Davis

Submitted to: Frontiers in Veterinary Infectious Diseases
Publication Type: Popular Publication
Publication Acceptance Date: 8/1/2020
Publication Date: 9/25/2020
Citation: Chanthavixay, G., Kern, C., Wang, Y., Saelao, P., Lamont, S.J., Gallardo, R.A., Rincon, G., Zhou, H. 2020. Integrated transcriptome and histone modification analysis reveals NDV infection under heat stress affects bursa development and proliferation in susceptible chicken line. Frontiers in Veterinary Infectious Diseases. 11. https://doi.org/10.3389/fgene.2020.567812.
DOI: https://doi.org/10.3389/fgene.2020.567812

Interpretive Summary: A combination of abiotic and biotic factors can highly impact the production potential of many farm raised animals. In chicken, factors such as heat stress and the threat of disease risk to greatly impact the poultry community, specifically in rural nations. This study uses a combination of gene expression and chromatin state prediction to understand the compound effects of these two factors in chickens. By understand the mechanism influencing the changes in gene expression when exposed to stress we can further the potential in identifying the genetic root of disease states. This study found that chromatin states can predict the alterations in gene expression of chickens when exposed to newcastle disease virus and heat stress. These regions can be identified as regulatory regions that have control over how the host is able to respond to stress on a genetic level.

Technical Abstract: Two environmental factors, Newcastle disease and heat stress, are concurrently negatively impacting poultry worldwide and warrants greater attention into developing genetic resistance within chickens. Using two genetically distinct and highly inbred layer lines, Fayoumi and Leghorn, we explored how different genetic backgrounds affect the bursal response to a treatment of simultaneous Newcastle disease virus (NDV) infection at 6 days post-infection while under chronic heat stress. The bursa is a primary lymphoid organ within birds and is crucial for the development of B cells. By performing RNA-seq and ChIP-seq targeting histone modifications on bursa samples, differential gene expression revealed that Leghorn has a stronger response than Fayoumi where there was significant down-regulation in genes involved in cell proliferation, cell cycle, and cell division. Interestingly, we also found greater differences in histone modification levels in response to treatment in Leghorns than Fayoumis, and biological processes enriched in associated target genes of H3K27ac and H3K4me1 were similarly associated with cell cycle and receptor signaling of lymphocytes. Lastly, we found candidate variants between the two genetic lines within exons of differentially expressed genes and regulatory elements with differential histone modification enrichment between the lines, which provides a great starting point for understanding the effects of genetic variation on NDV resistance under heat stress. This study provides further understanding of the cellular mechanisms affected by NDV infection and heat stress in chicken bursa and identified potential genes and regulatory regions that may be targets for developing genetic resistance within chickens or functional studies of genetic variants during treatment.