Influenza A pathway analysis of highly pathogenic avian influenza virus (H5N1) infection in genetically disparate Ri chicken lines.

Influenza A/H5N1 virus is a highly pathogenic (HPAIV) and contagious zoonotic virus that can be transmitted to humans. In the present study, infection with this virus and differential gene expression analyses were carried out with genetically resistant and susceptible Ri chicken lines that are native to Vietnam. A total of 20 four-week-old Ri chickens from each line were inoculated with the highly pathogenic H5N1 avian influenza virus (5 chickens/group). On day 3 post-infection, the total tracheal RNA was sequenced. Differentially expressed genes in the influenza A pathway, including signaling pathway-related genes, were validated by reverse transcription quantitative real-time PCR (RT-qPCR). The resistant and susceptible lines showed significant differences in gene expression and multiple biological functions. Compared to expression in the susceptible line, in the resistant line, the expression of MX1, STAT1, IRF7, and TLR3 was upregulated, while that of BF1 was downregulated. Genes from the interferon (IFN) and cytokine families, which regulate the immune system, were highly expressed in the HPAIV infected resistant line. Finally, significant differences were observed in the expression of genes encoding components of the Jak-STAT and TLR signaling pathways between the two chicken lines. Collectively, our findings suggest that HPAIV-resistant and -susceptible Ri chicken lines differed in immunity upon infection. Understanding the regulation of immune pathways against HPAIV will help to better understand the mechanisms of immune regulation in chickens.