Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging and highly pathogenic coronavirus that causes coronavirus disease (COVID-19), and might even lead to death. Circular RNAs (circRNAs), a new type of RNAs, are implicated in viral pathogenesis and host immune responses. However, their dynamic expression patterns and functions during SARS-CoV-2 infection remain to be unclear. We herein performed genome-wide dynamic analysis of circRNAs in human lung epithelial cells infected with SARS-CoV-2 at four time points. A total of 6118 circRNAs were identified at different genomic locations, including 5641 known and 477 novel circRNAs. Notably, a total of 42 circRNAs were significantly dysregulated, wherein 17 were up-regulated and 25 were down-regulated following infection at multiple phases. The gene ontology and KEGG enrichment analyses revealed that the parental genes of circRNAs were mainly involved in immune and inflammatory responses. Further, the RNA binding protein (RBP) prediction analysis indicated that the dysregulated circRNAs could regulate mRNA stability, immunity, cell death by binding specific proteins. Additionally, the circRNA-miRNA-gene network analysis showed that circRNAs indirectly regulated gene expression by absorbing their targeted miRNAs. Collectively, these results shed light on the roles of circRNAs in virus-host interactions, facilitating future studies on SARS-CoV-2 infection and pathogenesis.
Surveillance of recombinant enterovirus 71 (EV71) and subgenotype replacement is vital for preventing and controlling hand, foot, and mouth disease (HFMD) outbreaks. Despite this, data on recombinant variants and phylogeny of circulating EV71 strains in mainland China are limited. In this study, recombinant variants of EV71 were identified in mainland China from 2009 to 2018. Phylogenetic analysis indicated that except for individual strains (CQ2014-86/CQ/CHN/2014 and EV71/ Xiamen/2009 (B5)), almost all of the EV71 strains in mainland China belonged to the subgenotype C4a. Analysing complete genome sequences of 196 EV71 isolates, 3 intertypic recombination strains (VR1432, 30-2/2015/BJ, and Guangdong-2009) and 5 intratypic recombination strains (EV71/P1034/2013, VR1432, Henan-ZMD/CHN/2012, Hubei-WH/CHN/2012, and EV71/P868/2013/China) were identified among naturally circulating EV71. The breakpoints of these recombinant strains were located within the P1, P2, and P3 encoding regions. Notably, a double recombinant (VR1432) resulting from recombination between EV71 subgenotype C4a and C4b strain SHZH98 and a CA8 strain Donovan was identified. This study reports these specific intertypic and intratypic recombination events for the first time highlighting the importance of genetic recombination in the emergence of new enterovirus variants.
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