Multiple Transcriptome Analyses Reveal the Selected lncRNA-mRNA and circRNA-mRNA Networks in HepG2 Cells Expressing Genotype 4 Swine Hepatitis E Virus ORF3

(1) Background: Swine hepatitis E (SHE) is a novel zoonotic disease caused by the swine hepatitis E virus. Open Reading Frame 3 (ORF3) is an important virulence protein of swine hepatitis E virus, which promotes the survival and replication of the virus within host cells by regulating the ERK pathway, modulating the transport of growth factors that affect apoptosis, and facilitating the transmission of death signals during HEV infection. (2) Methods: In our previous study, we used adenovirus-mediated overexpression of HEV-4 in swine ORF3 in HepG2 cells, extracted total RNA, and performed high-throughput lncRNA, circRNA, and transcriptome sequencing. Based on the role of ORF3 in regulating the innate immunity of host cells, maintaining ERK activity, inhibiting the transport of growth factors, and suppressing the immune response, the pathways and differentially expressed genes were screened. A clustering analysis was conducted on circRNAs and lncRNAs, which were significantly differentially expressed across the four pathways, and a regulatory network of circRNA-miRNA and lncRNA-mRNA was constructed. (3) Results: In this study, a total of 24 circRNAs and 4 lncRNAs were screened in HepG2 cells expressing ORF3 of HEV-4 in swine, including 8 circRNAs that regulate host cell innate immunity and 18 circRNAs that maintain ERK activity. Four circRNAs inhibited growth factor transport, and three circRNAs inhibited immune responses, predicting the regulatory networks of circRNA-miRNA and lncRNA-mRNA, respectively. (4) Conclusions: In this study, differential genes involved in regulating host cell innate immunity, maintaining ERK activity, inhibiting growth factor transport, and inhibiting immune response processes were successfully screened in HepG2 cells expressing ORF3 in HEV-4 in swine, and the regulatory networks of circRNA-miRNA and lncRNA-mRNA were predicted, respectively, which laid a foundation for further elucidating the function of swine hepatitis E virus ORF3 and elucidating the infection mechanism of swine hepatitis E virus.