Chicken miR-26a-5p modulates MDA5 during highly pathogenic avian influenza virus infection

Authors: VU, THI HAO - Chung-Ang University; HEO, JUBI - Chung-Ang University; KANG, SUYEON - Chung-Ang University; KIM, CHAEEUN - Chung-Ang University; Lillehoj, Hyun; HON, YEONG HO - Chung-Ang University

Submitted to: Developmental and Comparative Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2023
Publication Date: 12/1/2023
Citation: Vu, T., Heo, J., Kang, S., Kim, C., Lillehoj, H.S., Hon, Y. 2023. Chicken miR-26a-5p modulates MDA5 during highly pathogenic avian influenza virus infection. Developmental and Comparative Immunology. Vol.149/104921. https://doi.org/10.1016/j.dci.2023.104921.
DOI: https://doi.org/10.1016/j.dci.2023.104921

Interpretive Summary: Avian influenza viruses (AI viruses) cause severe damage to poultry worldwide, and currently, there are no effective control strategies for AI viruses. Effective control strategy for AI viruses is timely needed but there is a lack of fundamental knowledge on how virus interacts with host immune system. In this paper, ARS scientists collaborated with scientists in South Korea and Vietnam to investigate the role of MicroRNAs (miRNAs) which are small, non-coding RNAs that regulate gene expression. In chickens, one type of miRNA, miR-26a-5p, has been shown to promote chicken ovarian cell proliferation, but the potential roles of the miRNAs in regulating immune responses, especially, by targeting the MDA5 gene in avian species, have not been extensively studied. In a previous study done by Vietnam and Korean groups, they identified 10 miRNA transcripts associated with host resistance to AI in the lung tissues of Vietnamese indigenous chicken lines infected with a highly pathogenic avian influenza virus, (HPAIV)-H5N1 following infection. In this study, the expression of gga-miR-26a-5p, which is one of the candidate immune-related miRNAs could regulate the immune response by interacting with the chicken MDA5 gene. These results collectively suggest an important role of immunological functions of gga-miR-26a-5p in host resistance to AI virus, but further studies are necessary to understand its crucial roles in the innate immune responses of chickens to AI viruses.

Technical Abstract: MicroRNAs play crucial roles in immune-related pathways in host animals. In this study, we aimed to investigate the systemic biological function of gga-miR-26a-5p, a chicken miRNA, in the immune responses to HPAIV H5N1 infection in the Vietnamese Ri chicken line. Our results showed a significant downregulation in gga-miR-26a expression in the lung tissue of Ri chickens during HPAIV H5N1 infection. Overexpression of gga-miR-26a and the reporter construct, either containing the wildtype or mutant melanoma differentiation-associated protein 5 (MDA5) 3' untranslated region (3' UTR)-luciferase, into a chicken fibroblast cell line, revealed that gga-miR-26a can act as a direct translational repressor of MDA5 by targeting the 3' UTRs. Additionally, miR-26a negatively regulated the expression of the signaling molecules related to the MDA5 signaling pathway, including MDA5, mitochondrial antiviral-signaling (MAVS), interferon regulatory factor 7 (IRF7), p38 mitogen-activated protein kinases, and nuclear factor-kappa B (NF-'B). Moreover, downstream of the IRF7 and NF-'B signaling pathway, the proinflammatory cytokines such as IL-1ß, IFN-', IFN-a, IFN-ß, and the interferon-stimulated gene (Mx1) were, likewise, downregulated by the overexpression of gga-miR-26a. These findings suggest that gga-miR-26a-5p serves as an important regulator in the MDA5 signaling pathway and antiviral response. Overall, our results contribute to an improved understanding of the biological functions of gga-miR-26a-5p, alongside the mechanisms underlying the MDA5 signaling pathway, and the antiviral response to HPAIV-H5N1 infection in chickens. Keywords: miR-26a; chicken; MDA5; chicken influenza virus; H5N1