scholarly journals Type III Interferon Restriction by Porcine Epidemic Diarrhea Virus and the Role of Viral Protein nsp1 in IRF1 Signaling

2017 ◽  
pp. JVI.01677-17 ◽  
Author(s):  
Qingzhan Zhang ◽  
Hanzhong Ke ◽  
Anthony Blikslager ◽  
Takashi Fujita ◽  
Dongwan Yoo

Type III interferons (IFN-λs) play a vital role to maintain the antiviral state of the mucosal epithelial surface in the gut, and in turn, enteric viruses may have evolved to evade the type III IFN responses during infection. To study of the possible immune evasion of porcine epidemic diarrhea virus (PEDV) from type III IFN response, a line of porcine intestinal epithelial cells was developed as a cell model for PEDV replication. IFN-λ1 and IFN-λ3 inhibited the PEDV replication, indicating the anti-PEDV activity of type III IFNs. Of the 21 PEDV proteins, nsp1, nsp3, nsp5, nsp8, nsp14, nsp15, nsp16, ORF3, E, M, and N were found to suppress the type III IFN activities, and the IRF1 signaling mediated the suppression. PEDV specifically inhibited IRF1 nuclear translocation. Peroxisome is the innate antiviral signaling platform for activation of IRF1-mediated IFN-λ production, and peroxisomes were found to decrease in number in PEDV-infected cells. PEDV nsp1 blocked the nuclear translocation of IRF1 and reduced the number of peroxisomes to suppress IRF1-mediated type III IFNs. Mutational studies showed the conserved residues of nsp1 were crucial for IRF1-mediated IFN-λ suppression. Our study for the first time provides the evidence that the porcine enteric virus PEDV downregulates and evades the IRF1-mediated type III IFN responses by reducing the peroxisomes.IMPORTANCEPorcine epidemic diarrhea virus (PEDV) is a highly contagious enteric coronavirus emerged in swine in the US and has caused severe economic losses. PEDV targets the intestinal epithelial cells in the gut, and intestinal epithelial cells selectively induce and respond to the production of type III interferons (IFNs). However, little is known about modulation of type III IFN response by PEDV in the intestinal epithelial cells. In this study, we established a porcine intestinal epithelial cell model for PEDV replication. We found that PEDV inhibited the IRF1-mediated type III IFN production by decreasing the peroxisomes in number in the porcine intestinal epithelial cells. We also demonstrated that the conserved residues in the PEDV nsp1 protein were crucial for IFN suppression. This study for the first time showed the PEDV evasion of type III IFN response in the intestinal epithelial cells. It provides valuable information on the host cell-virus interactions not only for PEDV but also other enteric viral infections in swine.

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 644
Author(s):  
Yajing Zhou ◽  
Zhanshi Ren ◽  
Shuai Zhang ◽  
Haifei Wang ◽  
Shenglong Wu ◽  
...  

Porcine epidemic diarrhea virus (PEDV) infects intestinal epithelial cells, destroys the intestinal mucosal barrier and then causes diarrhea in piglets. Glucagon-like peptide-2 (GLP-2) is a specific intestinal growth hormone that promotes the repair of damaged intestinal mucosa and improves the intestinal barrier. In this study, we investigated the functions of porcine GLP-2 gene in regulating PEDV infection. The intestinal tissues with damaged intestinal structures caused by PEDV infection were first confirmed and collected. Expression analysis indicated that the GLP-2 gene was expressed in the duodenum, jejunum and ileum tissues, and the mRNA level was significantly down-regulated in jejunum and ileum of piglets with damaged intestinal mucosa. Infection of PEDV to porcine small intestinal epithelial cells in vitro showed that GLP-2 gene was significantly decreased, which was consistent with the expression pattern in intestinal tissues. In addition, we silenced the GLP-2 gene by shRNA interfering and found that the copy numbers of PEDV were remarkably increased in the GLP-2 gene silencing cells. Our findings suggest that the GLP-2 gene was potentially involved in regulating PEDV infection and in maintaining the integrity of the intestinal mucosal barrier structure, which could contribute to our understanding of the mechanisms of PEDV pathogenesis and provide a theoretical basis for the identification and application of resistant genes in pig selective breeding for porcine epidemic diarrhea.


2020 ◽  
Author(s):  
Jacob A. Van Winkle ◽  
David A. Constant ◽  
Lena Li ◽  
Timothy J. Nice

ABSTRACTInterferon (IFN) family cytokines stimulate genes (ISGs) that are integral to antiviral host defense. Type I IFNs act systemically whereas type III IFNs act preferentially at epithelial barriers. Among barrier cells, intestinal epithelial cells (IECs) are particularly dependent on type III IFN for control and clearance of virus infection, but the physiological basis of this selective IFN response is not well understood. Here, we confirm that type III IFN treatment elicits robust and uniform ISG expression in neonatal mouse IECs and inhibits replication of IEC-tropic rotavirus. In contrast, type I IFN elicits a marginal ISG response in neonatal mouse IECs and does not inhibit rotavirus replication. In vitro treatment of IEC organoids with type III IFN results in ISG expression that mirrors the in vivo type III IFN response. However, the response of IEC organoids to type I IFN is strikingly increased relative to type III IFN in magnitude and scope. The expanded type I IFN-specific response includes pro-apoptotic genes and potentiates toxicity triggered by tumor necrosis factor alpha (TNFα). The ISGs stimulated in common by types I and III IFN have strong interferon-stimulated response element (ISRE) promoter motifs, whereas the expanded set of type I IFN-specific ISGs, including pro-apoptotic genes, have weak ISRE motifs. Thus, preferential responsiveness of IECs to type III IFN in vivo enables selective ISG expression during infection that confers antiviral protection but minimizes disruption of intestinal homeostasis.


2018 ◽  
Author(s):  
Kalliopi Pervolaraki ◽  
Soheil Rastgou Talemi ◽  
Dorothee Albrecht ◽  
Felix Bormann ◽  
Connor Bamford ◽  
...  

AbstractIt is currently believed that type I and III interferons (IFNs) have redundant functions. However, the preferential distribution of type III IFN receptor on epithelial cells suggests functional differences at epithelial surfaces. Here, using human intestinal epithelial cells we could show that although both type I and type III IFNs confer an antiviral state to the cells, they do so with distinct kinetics. Type I IFN signaling is characterized by an acute strong induction of interferon stimulated genes (ISGs) and confers fast antiviral protection. On the contrary, the slow acting type III IFN mediated antiviral protection is characterized by a weaker induction of ISGs in a delayed manner compared to type I IFN. Moreover, while transcript profiling revealed that both IFNs induced a similar set of ISGs, their temporal expression strictly depended on the IFNs, thereby leading to unique antiviral environments. Using a combination of data-driven mathematical modeling and experimental validation, we addressed the molecular reason for this differential kinetic of ISG expression. We could demonstrate that these kinetic differences are intrinsic to each signaling pathway and not due to different expression levels of the corresponding IFN receptors. We report that type III IFN is specifically tailored to act in specific cell types not only due to the restriction of its receptor but also by providing target cells with a distinct antiviral environment compared to type I IFN. We propose that this specific environment is key at surfaces that are often challenged with the extracellular environment.Author summaryThe human intestinal tract plays two important roles in the body: first it is responsible for nutrient absorption and second it is the primary barrier which protects the human body from the outside environment. This complex tissue is constantly exposed to commensal bacteria and is often exposed to both bacterial and viral pathogens. To protect itself, the gut produces, among others, secreted agents called interferons which help to fight against pathogen attacks. There are several varieties (type I, II, and III) of interferons and our work aims at understanding how type I and III interferon act to protect human intestinal epithelial cells (hIECs) during viral infection. In this study, we confirmed that both interferons can protect hIECs against viral infection but with different kinetics. We determined that type I confer an antiviral state to hIECs faster than type III interferons. We uncovered that these differences were intrinsic to each pathway and not the result of differential abundance of the respective interferon receptors. The results of this study suggest that type III interferon may provide a different antiviral environment to the epithelium target cells which is likely critical for maintaining gut homeostasis. Our findings will also help us to design therapies to aid in controlling and eliminating viral infections of the gut.


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