Comparative analysis of miRNAs in exosomes released by sheeppox virus-infected ovine testicular cells

Exosomes, secreted by various cells, are nanometer-scale vesicles with the functions in intercellular communication. To understand a role of exosomal miRNAs in the sheeppox virus infection, exosomes were isolated from sheeppox virus-infected sheep testicular cells 0 h, 24 h and 72 h post infection. The results of transmission electron microscopy and size distribution showed that all three exosome samples were spherical particles with negatively-stained membrane, ranging from 39 nm to 127 nm in diameter. A total of 106 known and 279 novel miRNAs were identified, and 78 known and 54 novel miRNAs were commonly detected in three exosome samples. Compared with the exosomes by the uninfected controls, a total of 34 known miRNAs were aberrantly expressed in the exosomes from infected cells. In agreement with the sequencing data, the expression of oar-miR-21 and oar-miR-10b was shown to be the highest in exosomes at 24 h after SPPV-infected, and the expression of oar-let-7f was the highest in exosomes at 72 h. Conversely, the expression of oar-let-7b and oar-miR-221 was significantly decreased 24 h and 72 h post infection compared with 0 h. The analysis results also revealed that differentially expressed miRNAs were mostly involved in an immune system process and stimulus response. These results provide rich data to further investigate a role of exosomal miRNAs in SPPV-host interactions.