Cellular microRNA miR-c89 inhibits replication of porcine reproductive and respiratory syndrome virus by targeting the host factor porcine retinoid X receptor ß.

MicroRNAs (miRNAs) play critical roles in the complex networks of virus-host interactions. Our previous research showed that porcine reproductive and respiratory syndrome virus (PRRSV) infection markedly upregulates miR-c89 expression, suggesting that miR-c89 may play an important role in PRRSV infection. The present study sought to determine the function of miR-c89 and its molecular mechanism during PRRSV infection. Using quantitative reverse transcription PCR (RT-qPCR) verification, we demonstrated that both highly pathogenic PRRSV and low-pathogenic PRRSV infection induced miR-c89 expression. The overexpression of miR-c89 significantly suppressed the replication of a variety of PRRSV strains, regardless of the timing of infection. Further, miR-c89 can directly target the 3'UTR of porcine retinoid X receptor ß (RXRB) mRNA in a sequence-specific manner. Knockdown affected RXRB expression, as siRNA can suppress the replication of a variety of PRRSV strains. This work not only provides new insights into PRRSV-cell interactions, but also highlights the potential for the use of miR-c89 in the development of new antiviral strategies to combat PRRSV infection.