Persistent Infection of Simian Foamy Virus Derived from the Japanese Macaque Leads to the High-Level Expression of microRNA that Resembles the miR-1 microRNA Precursor Family

MicroRNAs (miRNAs) are a group of small non-coding RNAs that suppress the expression of target mRNAs. The seed sequence of miRNA plays a crucial role in recognizing the 3′-untranslated region of the target mRNA. Cells infected with a simian foamy virus (SFV) isolated from an African green monkey (Chlorocebus aethiops) (SFVcae) showed high expression levels of viral miRNAs encoded in the long terminal repeat of SFVcae. In the present study, we investigated the roles and expression of miRNAs derived from an SFV isolated from a Japanese macaque (Macaca fuscata) (SFVmfu) using next-generation sequencing technologies. The results obtained showed that SFVmfu also expressed viral miRNAs; however, the seed sequences of most miRNAs derived from SFVmfu differed from those reported previously from SFVcae. Cells persistently infected with SFVmfu strongly expressed an miRNA with the same seed sequence as the miR-1 microRNA precursor family. Luciferase reporter assays indicated that this miRNA down-regulates the expression of adenylyl cyclase-associated protein 1, which is up-regulated in several solid tumors. The present results suggest that SFVmfu utilizes viral miRNAs to establish long-term co-existence with the Japanese macaque.