The purpose of this study is to investigate the impact of host circular RNA(circRNA)on the proliferation of porcine deltacoronavirus(PDCoV).Among the significantly downregulated cir-cRNAs identified during PDCoV infection from circRNA expression profiles in ST cells,circCAM-SAP2 was selected for further analysis.The gene origin and junction sequence of circCAMSAP2 were validated using the online Ensembl database and Sanger sequencing.The molecular character-istics of circCAMSAP2 were determined through nucleoplasmic separation assays and RNase R tests.Additionally,the differential expression of circCAMSAP2 during PDCoV infection was con-firmed using RT-qPCR.Overexpression and knockdown experiments were conducted to investigate the regulatory role of circCAMSAP2 in PDCoV replication.The results indicated that circCAM-SAP2 is a circRNA derived from exon 2 of the CAMSAP2 gene through reverse splicing.It is re-sistant to RNase R,has a length of 260 nucleotides,and is predominantly located in the cytoplasm.circCAMSAP2 expression is downregulated during PDCoV replication.Overexpression of circ-CAMSAP2 inhibited PDCoV proliferation,while knockdown promoted it in ST cells.These find-ings suggest that porcine circCAMSAP2 acts as a negative regulator of PDCoV replication and could serve as a potential target for the development of anti-PDCoV therapeutics.

The purpose of this study is to investigate the impact of host circular RNA(circRNA)on the proliferation of porcine deltacoronavirus(PDCoV).Among the significantly downregulated cir-cRNAs identified during PDCoV infection from circRNA expression profiles in ST cells,circCAM-SAP2 was selected for further analysis.The gene origin and junction sequence of circCAMSAP2 were validated using the online Ensembl database and Sanger sequencing.The molecular character-istics of circCAMSAP2 were determined through nucleoplasmic separation assays and RNase R tests.Additionally,the differential expression of circCAMSAP2 during PDCoV infection was con-firmed using RT-qPCR.Overexpression and knockdown experiments were conducted to investigate the regulatory role of circCAMSAP2 in PDCoV replication.The results indicated that circCAM-SAP2 is a circRNA derived from exon 2 of the CAMSAP2 gene through reverse splicing.It is re-sistant to RNase R,has a length of 260 nucleotides,and is predominantly located in the cytoplasm.circCAMSAP2 expression is downregulated during PDCoV replication.Overexpression of circ-CAMSAP2 inhibited PDCoV proliferation,while knockdown promoted it in ST cells.These find-ings suggest that porcine circCAMSAP2 acts as a negative regulator of PDCoV replication and could serve as a potential target for the development of anti-PDCoV therapeutics.