Abstract
IMPORTANCE: Avian influenza virus (AIV) has emerged as a serious threat worldwide. In poultry, AIV can be divided into highly pathogenic AIV (HPAIV) and low pathogenic AIV (LPAIV). Exosomes are small vesicles released from donor cells that transmit cargo such as microRNAs (miRNAs), where exosomal miRNA can regulate target gene expression. OBJECTIVE: By profiling exosomal miRNAs from chickens infected with HPAIV and LPAIV, we provide insights into the immunological functions of exosomal miRNAs in AIV infection as well as into the development of strategies for its control. METHODS: This study analyzed the exosomal miRNA expression profiles of non-infected, LPAIV-infected, and HPAIV-infected chickens using small RNA sequencing. miRDB and Gene Ontology (GO) were used to predict immune-related target genes, and GO and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed. Reverse transcription quantitative polymerase chain reaction was conducted to validate the expression levels of miRNAs (gga-miR-1434, gga-miR-1662, gga-miR-1559-5p, and gga-miR-375). RESULTS: We identified 148 DE miRNAs in total: 103 in LPAIV-EXO vs. CTRL-EXO, 54 in HPAIV-EXO vs. CTRL-EXO, and 98 in HPAIV-EXO vs. LPAIV-EXO, with partial overlap among groups. In the GO and KEGG analyses, the mitogen-activated protein kinase signaling pathway was the most enriched pathway in all comparisons. CONCLUSIONS AND RELEVANCE: This report provides insight into the molecular mechanisms by which exosomal miRNAs are related to immune-related pathways in HPAIV and LPAIV infections and is expected to be helpful for novel vaccine development and useful biomarkers for virus infections.