Discovery of Kaposi's sarcoma herpesvirus-encoded circular RNAs and a human antiviral circular RNA

Human herpesviruses are known to interact with non-protein encoding RNAs like microRNAs and long noncoding RNAs. Circular RNAs (circRNAs) are recently discovered noncoding RNAs that are long-lived and resistant to exonucleases, and that bind to other RNAs or RNA-binding proteins. This research aimed to investigate interaction between circRNAs and Kaposi's sarcoma herpesvirus (KSHV). We identified a certain human circRNA that can work as an antiviral molecule by suppressing crucial viral genes. Further, multiple circRNAs were found to be encoded in the KSHV genome and expressed in KSHV-infected cells as well as KSHV-positive patients. We discovered a new layer of host-virus interactions with circRNAs which are potentially applicable to other viruses, and these antiviral circRNAs or viral circRNAs may represent novel therapeutic targets.