Tandem Mass Tag-Based Quantitative Proteome Analysis of Porcine Deltacoronavirus (PDCoV)-Infected LLC Porcine Kidney Cells.

Porcine deltacoronavirus (PDCoV) is a newly emerging porcine pathogenic enteric coronavirus that can cause diarrhea, vomiting, dehydration, and a high mortality rate in piglets. At present, the understanding of PDCoV pathogenesis is very limited, which seriously hinders effective prevention and control. In this study, liquid chromatography tandem-mass spectrometry (LC-MS/MS) combined with tandem mass tag (TMT) labeling was performed to compare the differential expression of proteins in PDCoV-infected and mock-infected LLC-PK cells at 18 h post-infection (hpi). In addition, the parallel reaction monitoring (PRM) technique was used to verify the quantitative proteome data. A total of 4624 differentially expressed proteins (DEPs) were quantitated, of which 128 were significantly upregulated, and 147 were significantly downregulated. Bioinformatics analysis revealed that these DEPs were involved mainly in the defense response, apoptosis, and the immune system, and several DEPs may be related to interferon-stimulated genes and the immune system. Based on DEP bioinformatics analysis, we propose that PDCoV infection may utilize the apoptosis pathway of host cells to achieve maximum viral replication. Meanwhile, the host may be able to stimulate the transcription of interferon-stimulated genes (ISGs) through the JAK/STAT signaling pathway to resist the virus. Overall, in this study, we presented the first application of proteomics analysis to determine the protein profile of PDCoV-infected cells, which provides valuable information with respect to better understanding the host response to PDCoV infection and the specific pathogenesis of PDCoV infection.