Nonspreading Rift Valley Fever Virus Infection of Human Dendritic Cells Results in Downregulation of CD83 and Full Maturation of Bystander Cells.

Nadia Oreshkova,Nadia Oreshkova,Lotte Spel,Marianne Boes,Rianka P M Vloet,Jeroen Kortekaas,Rob J M Moormann,Paul J Wichgers Schreur,Ramin M Hakami

doi:10.1371/journal.pone.0142670

Abstract

Vaccines based on nonspreading Rift Valley fever virus (NSR) induce strong humoral and robust cellular immune responses with pronounced Th1 polarisation. The present work was aimed to gain insight into the molecular basis of NSR-mediated immunity. Recent studies have demonstrated that wild-type Rift Valley fever virus efficiently targets and replicates in dendritic cells (DCs). We found that NSR infection of cultured human DCs results in maturation of DCs, characterized by surface upregulation of CD40, CD80, CD86, MHC-I and MHC-II and secretion of the proinflammatory cytokines IFN-β, IL-6 and TNF. Interestingly, expression of the most prominent marker of DC maturation, CD83, was consistently downregulated at 24 hours post infection. Remarkably, NSR infection also completely abrogated CD83 upregulation by LPS. Downregulation of CD83 was not associated with reduced mRNA levels or impaired CD83 mRNA transport from the nucleus and could not be prevented by inhibition of the proteasome or endocytic degradation pathways, suggesting that suppression occurs at the translational level. In contrast to infected cells, bystander DCs displayed full maturation as evidenced by upregulation of CD83. Our results indicate that bystander DCs play an important role in NSR-mediated immunity.

Highlights

Rift Valley fever virus (RVFV) replicon particles, known as nonspreading RVFV (NSR), resemble authentic RVFV by structure and infectivity [1]
The results show that neither NSR infection, nor a combination of LPS stimulation and NSR infection significantly affected the total levels of CD83 mRNA, as compared to control stimulations (Fig 5)
To be able to discriminate between GFP+ and GFP- in the dendritic cells (DCs) population and to exclude possible arrest of host mRNA nuclear transport, which is a common mechanism used by viruses to counteract cellular antiviral mechanisms [29], we evaluated subcellular location of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), CD80 and CD83 mRNAs using a fluorescence in situ hybridisation (FISH) technique

Summary

Introduction

Rift Valley fever virus (RVFV) replicon particles, known as nonspreading RVFV (NSR), resemble authentic RVFV by structure and infectivity [1]. They retain the genes encoding proteins necessary for viral RNA amplification, but are deprived of the gene encoding the structural glycoproteins, required for the generation of progeny virions. The absence of the NSs gene adds to the safety profile of NSR and provides an expression slot for a protein of interest. These combined features render NSR an intrinsically safe and powerful platform for the development of vaccines

Methods

Results

Conclusion