Extracellular Vesicles Are Conveyors of the NS1 Toxin during Dengue Virus and Zika Virus Infection

Abstract

Extracellular vesicles (EVs), produced during viral infections, are of emerging interest in understanding infectious processes and host–pathogen interactions. EVs and exosomes in particular have the natural ability to transport nucleic acids, proteins, and other components of cellular or viral origin. Thus, they participate in intercellular communication, immune responses, and infectious and pathophysiological processes. Some viruses are known to hijack the cell production and content of EVs for their benefit. Here, we investigate whether two pathogenic flaviviruses i.e., Zika Virus (ZIKV) and Dengue virus (DENV2) could have an impact on the features of EVs. The analysis of EVs produced by infected cells allowed us to identify that the non-structural protein 1 (NS1), described as a viral toxin, is associated with exosomes. This observation could be confirmed under conditions of overexpression of recombinant NS1 from each flavivirus. Using different isolation methods (i.e., exosome isolation kit, size exclusion chromatography, Polyethylene Glycol enrichment, and ELISA capture), we showed that NS1 was present as a dimer at the surface of excreted exosomes, and that this association could occur in the extracellular compartment. This finding could be of major importance in a physiological context. Indeed, this capacity of NS1 to address EVs and its implication in the pathophysiology during Dengue or Zika diseases should be explored. Furthermore, exosomes that have demonstrated a natural capacity to vectorize NS1 could serve as useful tools for vaccine development.

Zika virus modulates mitochondrial dynamics, mitophagy, and mitochondria-derived vesicles to facilitate viral replication in trophoblast cells

“…Western blot analysis revealed that sEVs expressed common EV markers like CD63, CD9, TSG101, and ALIX, which are involved in sEV biogenesis or trafficking, and did not express calnexin, an ER marker that was used as a negative control ( Figure 6C ) ( 27 ). Interestingly, the infected sEVs also contained ZIKV NS1, which is in line with previous report on presence of NS1 dimers on surface of exosome-like EVs ( 28 ). Further characterization of sEV morphology was analyzed by TEM that revealed the presence of small, double-membraned nanovesicles ( Figure 6D ).…”

Subcapsular sinus macrophages maximize germinal center development in non-draining lymph nodes during blood-borne viral infection

“…Bacteria can produce toxins that enhance epithelial permeability to promote microbe dissemination ( 75 , 76 ). Recently, the concept of viral “toxins” has similarly emerged as a mechanism for viral dissemination, largely on the basis of work with flaviviruses ( 77 ). Viral toxins have been described as secreted viral proteins that promote endothelial barrier dysfunction to enhance viral escape.…”

Control of maternal Zika virus infection during pregnancy is associated with lower antibody titers in a macaque model

“…This suggests that the higher vRNA titers found early in infection in the viral non-controllers may exist in a form that we are unable to detect in a plaque assay. ZIKV vRNA and proteins can be incorporated into cell-derived extracellular vesicles that exhibit variable infectivity in cell culture ( 61 , 62 ). Thus, it is possible that vRNA packaged in extracellular vesicles is leading to higher vRNA loads early in infection in the viral non-controllers.…”