Circular RNAs (circRNAs) are a diverse class of RNAs with varying sizes, cellular abundance, and biological functions. Investigations from the past decade have revealed that circRNAs are ubiquitously found in eukaryotes and have defined the different biological roles of circRNAs to illuminate this previously unrecognized class of molecules. In the context of the immune system, immune responses and immune-related diseases alter circRNA expression. More recently, several oncogenic double-stranded DNA viruses have been found to encode circRNAs. In this review, we summarize the current understanding of circRNAs and their emerging functions in immune regulation and autoimmune disorders, and discuss the identification and potential roles of viral circRNAs during infections. Finally, we present promising areas for future investigations in the nascent field of circRNAs.

环状 RNA (circRNA) 是一类不同的 RNA，具有不同的大小、细胞丰度和生物学功能。过去十年的研究表明，circRNA在真核生物中普遍存在，并定义了circRNA的不同生物学作用，以阐明这一先前未被识别的分子类别。在免疫系统中，免疫反应和免疫相关疾病会改变 circRNA 表达。最近，人们发现几种致癌双链 DNA 病毒可以编码 circRNA。在这篇综述中，我们总结了目前对 circRNA 的理解及其在免疫调节和自身免疫性疾病中的新功能，并讨论了病毒 circRNA 在感染过程中的识别和潜在作用。最后，我们提出了 circRNA 新兴领域未来研究的有前景的领域。