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Porcine reproductive and respiratory syndrome (PRRS) is a highly contagious infectious disease caused by porcine reproductive and respiratory syndrome virus (PRRSV), which inflicts major economic losses on the global pig farming industry. Based on its similarity to highly pathogenic strains, the GDzj strain isolated in this study was predicted to be highly pathogenic. We therefore analyzed the pathogenicity of this strain experimentally in piglets. All piglets challenged with this virus experienced fever or high fever, loss of appetite, decreased food intake, daily weight loss, shortness of breath, and listlessness, and the necropsy results showed that they had experienced severe interstitial pneumonia. We then used the BAC system to construct a full-length cDNA infectious clone of GDzj, and the rescued virus displayed in vitro proliferation characteristics similar to those of the parental PRRSV strain. In summary, we successfully isolated a highly pathogenic PRRSV strain and constructed a full-length infectious cDNA clone from it, thereby providing an effective reverse genetics platform for further study of viral pathogenesis.

Porcine epidemic diarrhea virus (PEDV) causes severe economic loss in the pig industry each year. To better understand the relationship between cytokines and PEDV replication, in this study, pro-inflammatory cytokine and chemokine expression profiles in Vero cells infected with PEDV were analyzed. Real-time quantitative PCR assay indicated that IL-1α, IL-1β, TNF-α, CCL2, CCL5 and CXCL8 expression levels were significantly upregulated. Moreover, overexpression and siRNA silencing assays showed that overexpression of IL-1α, IL-1β, TNF-α, CCL2, CCL5 and CXCL8 could significantly inhibit PEDV replication, while silencing of IL-1α, IL-1β, TNF-α, CCL2, CCL5 and CXCL8 could significantly promote PEDV replication. Finally, a dual-luciferase reporter assay showed that nsp4 contributed to the expression of IL-1α, IL-1β, TNF-α, CCL2, CCL5 and CXCL8 via the NF-κB pathway. Together, these data determined that PEDV nsp4 could upregulate pro-inflammatory cytokine and chemokine expression, inhibiting viral replication in vitro. These results provided novel insights for understanding the roles of cytokines in PEDV replication.

Porcine epidemic diarrhea (PED) is an acute enteric disease caused by porcine epidemic diarrhea virus (PEDV). In China, variant PEDV causes severe watery diarrhea, vomiting, and dehydration in piglets, leading to very high morbidity and mortality. However, the pathogenesis of PEDV is still not fully understood. In our study, we analyzed the long noncoding RNA (lncRNA) and mRNA expression profiles of PEDV GDgh16 in infected Vero cells at 60 h postinfection. A total of 61,790 annotated mRNAs, 14,247 annotated lncRNAs and 1290 novel lncRNAs were identified. A total of 227 annotated lncRNAs and 13 novel lncRNAs were significantly and differentially expressed after viral infection. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) databases were used to identify genes adjacent to the lncRNAs, and it was found that these lncRNAs were enriched in pathways related to immune and antiviral responses. Next, we selected candidate lncRNAs and their predicted target genes for study. RT-qPCR demonstrated that these lncRNAs and genes were differentially expressed after PEDV infection. Our study investigated the function of lncRNAs involved in PEDV infection, providing new insight into the pathogenic mechanisms of PEDV.