Tissue-specific transcriptomic responses to avian reovirus inoculation in ovo

Authors: KHALID, ZUBAIR - Auburn University; FATHIMA, SHAHNA - Auburn University; HAUCK, RUEDIGER - Auburn University

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Problem: Avian reovirus (ARV) can cause a number of economically important diseases, but the molecular responses to ARV are not well characterized. Accomplishment: This study examined how infection with two different doses of ARV changed gene expression in liver, kidney, intestine, and bursa of chicken embryos. Livers had the highest viral loads 24 hours after the infection, while in kidney, intestine, and bursa the virus was detected only 48 hours after the infection and organs taken from embryos infected with the higher dose. In livers, and to a lesser extent in the intestines, a strong reaction of the antiviral parts of the immune system was detected. In kidneys and intestines, the expression of genes related to coagulation and wound healing was changed. The bursae exhibited a minimal immunity-related response. Contribution of accomplishment to solving the problem: These findings show clear differences in the molecular reaction of different tissues to infection with ARV. The results are part of a larger project on how ARV causes disease and how the host reacts to it. They will help in the interpretation of future experiments exploring how ARV cause disease and testing intervention methods.

Technical Abstract: Avian reovirus (ARV) infections significantly impact the global poultry industry, but host responses across infection models remain poorly characterized. Using specif-ic-pathogen-free chicken embryos, this study examined tissue-specific transcriptomic changes following in ovo inoculation with two doses of ARV S1133 at embryonic day 18. Quantitative PCR confirmed dose- and time-dependent viral replication, with the liver exhibiting the highest viral load at 24 hours post-inoculation (hpi), whereas the kidney, intestine, and bursa were only positive at 48 hpi with the higher viral dose. Tran-scriptomic profiling revealed the intestine mounted an extensive gene expression re-sponse, implicating early immune activation. Liver samples demonstrated strong up-regulation of antiviral pathways, including interferon signaling and viral replication inhibition, while kidneys and intestines were enriched for coagulation and wound healing pathways. The bursae exhibited minimal immunity-related responses, sug-gesting insufficient maturation. Functional analyses confirmed tissue-specific immune and metabolic adaptations to infection. These findings indicate that ARV replication efficiency and host molecular responses are dose-, tissue-, and time-dependent. Nota-bly, intestinal responses suggest preemptive immune engagement, while hepatic anti-viral mechanisms may play a critical role in restricting viral spread. This study estab-lishes foundational knowledge of host molecular responses to ARV in late-stage em-bryos, with implications for in ovo vaccination and early immunity.