Construction of <italic>PCIF1</italic> knockdown cell line and its effect on replication of porcine epidemic diarrhea virus

<bold>Objective</bold> The purpose of this study is to construct methyltransferase，phosphorylated C-terminal domain interacting factor 1（<italic>PCIF1</italic>） knockdown cell lines to efficiently investigate the effect and mechanism of <italic>PCIF1</italic> on porcine epidemic diarrhea virus （PEDV） replication. <bold>Method</bold> In this study，a <italic>PCIF1</italic> knockdown （<italic>PCIF1</italic>-KD） cell line was constructed using RNA interference （RNAi） technology.Initially，a <italic>PCIF1</italic>-specific targeting vector，pcDNA3.1-Double U6-mCherry-sh<italic>PCIF1</italic>，was constructed，and tranfected into African green monkey kidney cells （Vero-81） mediated by lipofectamine.The <italic>PCIF1</italic>-KD recombinant cells were then screened by geneticin，and then indentified by RT-qPCR and Western blotting.Finally，the replication capacity of the porcine epidemic diarrhea virus （PEDV） on the obtained recombinant <italic>PCIF1</italic>-KD cells was verified by RT-qPCR and Western blotting. <bold>Result</bold> The recombinant interference plasmid was successfully generated，as demonstrated by sequencing.The results of RT-qPCR and Western blotting showed that <italic>PCIF1</italic> was significantly knocked down in the recombinant Vero-81 cells，and thus a stable <italic>PCIF1</italic>-KD recombinant cell line，designated as sh-△<italic>PCIF1</italic>-Vero-81，was obtained.The level of PEDV replication was markedly suppressed in sh-△<italic>PCIF1</italic>-Vero-81 cells，and this inhibiting effect was magnified from 24 to 36 hours post-infection. <bold>Conclusion</bold> This study constructs a <italic>PCIF1</italic>-KD Vero-81 cell line，which shows substantial inhibition of PEDV proliferation in a time-dependent manner.The results of the study could provide a powerful tool to further investigate the effect of <italic>PCIF1</italic> on PEDV or to elucidate the molecular mechanism of how <italic>PCIF1</italic> interacts with PEDV.