Porcine parvovirus nonstructural protein NS1 activates NF-κB and it involves TLR2 signaling pathway

Abstract

Background: Porcine parvovirus (PPV) is a single-stranded DNA virus that causes porcine reproductive failure. It is of critical importance to study PPV pathogenesis for the prevention and control of the disease. NS1, a PPV non-structural protein, is participated in viral DNA replication, transcriptional regulation, and cytotoxicity. Our previous research showed that PPV can activate nuclear factor kappa B (NF-κB) signaling pathway and then up-regulate the expression of interleukin (IL)-6. Objectives: Herein, the purpose of this study is to determine whether the non-structural protein NS1 of PPV also has the same function. Methods: Real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR), enzyme-linked immunosorbent assay, western blot, immunofluorescence assay and small interfering RNA (siRNA) were used. Results: Our findings demonstrated that PPV NS1 protein can up-regulate the expression levels of IL-6 and tumor necrosis factor-alpha in a dose-dependent manner. Moreover, PPV NS1 protein was found to induce the phosphorylation of IκBα, then leading to the phosphorylation and nuclear translocation of NF-κB. In addition, the NS1 protein activated the upstream pathways of NF-κB. Meanwhile, TLR2-siRNA assay showed TLR2 plays an important role in the activation of NF-κB signaling pathway induced by PPV-NS1. Conclusions: These findings indicated that PPV NS1 protein induced the up-regulated of IL-6 expression through activating the TLR2 and NF-κB signaling pathways. In conclusion, these findings provide a new avenue to study the innate immune mechanism of PPV infection.

Integrated Analysis of miRNA-mRNA Expression in Mink Lung Epithelial Cells Infected With Canine Distemper Virus

“…The classical activation pathway is activated by most proinflammatory factors, such as TNF, interleukin 1 (IL-1), or viral and bacterial products. Several viral infections, including porcine parvovirus (PPV), herpes simplex virus (HSV) and measles virus (MV), were reported to activate NF-kappa B signaling pathway ( 40 – 42 ). Epstein-barr virus (EBV) could activate NF-kappa B signaling pathway and inhibit viral replication ( 43 ).…”

Scratching the Surface Takes a Toll: Immune Recognition of Viral Proteins by Surface Toll-like Receptors

“…TLR2 pathogen-associated molecular pattern (PAMP) recognition and signaling have also been shown to involve co-receptors such as CD14, and CD36 ( Figure 1 ) [ 9 ]. Because of TLR2’s ability to heterodimerize with several other TLRs, the list of PAMPs suggested to associate with TLR2 are substantial, including proteins from Epstein–Barr virus (EBV) [ 10 , 11 ], cytomegalovirus (CMV) [ 12 , 13 , 14 ], respiratory syncytial virus (RSV) [ 15 ], measles [ 16 ], hepatitis C virus (HCV) [ 17 , 18 , 19 , 20 , 21 , 22 ], herpes simplex virus -1 and -2 (HSV) [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ], coronaviruses [ 39 , 40 , 41 , 42 ], parvovirus [ 43 , 44 ], and norovirus [ 45 ].…”

“…PPV is a non-enveloped, single-stranded DNA virus in the Parvoviridae family and encodes two non-structural proteins, NS1 and NS2, and two structural proteins, VP1 and VP2 [ 99 ]. While little research has been done to investigate how PPV activates a surface TLR, there have been two studies demonstrating that the recognition of PPV by TLR2 may benefit the virus [ 43 , 44 ]. Jin et al demonstrated that PPV NS1 expressed by the pEGFP-N1-NS1 plasmid in HEK-293 cells induced the expression and production of TNF and IL-6 and that NS1-NF-κB signaling activation was mediated by TLR2 [ 43 ].…”

“…While little research has been done to investigate how PPV activates a surface TLR, there have been two studies demonstrating that the recognition of PPV by TLR2 may benefit the virus [ 43 , 44 ]. Jin et al demonstrated that PPV NS1 expressed by the pEGFP-N1-NS1 plasmid in HEK-293 cells induced the expression and production of TNF and IL-6 and that NS1-NF-κB signaling activation was mediated by TLR2 [ 43 ]. Xu et al used porcine PK-15 cells to demonstrate that infectious PPV induced apoptosis in a TLR2-dependent manner [ 44 ].…”

“…Interestingly, infectious PPV was required to activate NF-κB signaling as UV-IA PPV did not [ 44 ]. These studies suggested that PPV may utilize TLR2 to modulate the host response including inducing cytokine storm during PPV infection [ 43 , 44 ]. As UV-IA PPV did not induce a response and NS1 was required to activate TLR2, these studies suggest that surface TLRs may be activated in response to PPV post-replication ( Figure 3 ).…”