Discovery of an HIV-1-encoded circular RNA that enhances viral transcription

Circular RNAs (circRNAs) are a class of transcripts that are formed when portions of a pre-mRNA molecule are spliced together in a closed loop. Here, we discover a novel HIV-1-encoded viral circRNA present in patient-derived plasma and infected T-cell lines, demonstrating that an RNA retrovirus can generate circRNAs. This HIV-1-encoded circRNA is packaged within HIV-1 virions, binds the HIV-1 Tat protein, and enhances transcription from the HIV-1 promoter. Our study sheds lights on a previously overlooked aspect of HIV-1 transcription and presents interactions between viral proteins and viral circRNAs as novel mechanisms underlying viral pathogenesis.