Abstract
Interferon (IFN)-inducible protein 16 (IFI16) regulates human immunodeficiency virus replication by inducing innate immune responses as a DNA sensor. Human T-lymphotropic virus type 1 (HTLV-1), a delta retrovirus family member, has been linked to multiple diseases. Here, we report that IFI16 expression is induced by HTLV-1 infection or HTLV-1 reverse transcription intermediate (RTI) ssDNA90 transfection. IFI16 overexpression decreases HTLV-1 protein expression, whereas IFI16 knockdown increases it. Furthermore, the knockdown of IFI16 is followed by impaired innate immune responses upon HTLV-1 infection. In addition, IFI16 forms a complex with ssDNA90 and enhances ssDNA90-triggered innate immune responses. Collectively, our data suggest a critical role for IFI16 during HTLV-1 infection by interacting with HTLV-1 RTI ssDNA90 and restricting HTLV-1 replication.