Abstract
Subgroup J avian leukosis virus (ALV-J) is a major pathogen in poultry, causing substantial economic losses to the poultry industry worldwide. Exosomal small RNAs derived from virus-infected cells or biological fluids can serve as viral transmission vectors. However, the role and mechanism of exosomal miRNA in ALV-J infection are unclear. In this study, we demonstrated that exosomal microRNA-7-25207 (miR-7-25207) could increase the titers of ALV-J. Exosomes isolated from ALV-J-infected DF-1 cells (Exo-ALV-J) contained partial viral proteins from ALV-J and could transmit the infection to uninfected DF-1 cells, leading to productive infection. Additionally, the RNA expression profile of exosomes was altered following ALV-J infection. miRNA analysis revealed that the expression of exosomal miR-7-25207 increased. Overexpression of miR-7-25207 significantly increased the titers of ALV-J in transfected cells. Furthermore, miR-7-25207 directly suppressed the expression of Akt and PRC1. Akt, in turn, directly inhibited CyclinQ1 expression, while PRC1 directly interfered with YAF2 expression. In conclusion, ALV-J infection activates the expression of miR-7-25207, which is subsequently delivered via exosomes to uninfected cells, increasing ALV-J titers by targeting Akt-CyclinQ1 and PRC1-YAF2 dual pathways. These findings suggest that exosomal miR-7-25207 may serve as a potential biomarker for clinical parameters in ALV-J infection.