Zika virus: mapping and reprogramming the entry

Abstract

Background The flaviviridae family comprises single-stranded RNA viruses that enter cells via clathrin-mediated pH-dependent endocytosis. Although the initial events of the virus entry have been already identified, data regarding intracellular virus trafficking and delivery to the replication site are limited. The purpose of this study was to map the transport route of Zika virus and to identify the fusion site within the endosomal compartment. Methods Tracking of viral particles in the cell was carried out with confocal microscopy. Immunostaining of two structural proteins of Zika virus enabled precise mapping of the route of the ribonucleocapsid and the envelope and, consequently, mapping the fusion site in the endosomal compartment. The results were verified using RNAi silencing and chemical inhibitors. Results After endocytic internalization, Zika virus is trafficked through the endosomal compartment to fuse in late endosomes. Inhibition of endosome acidification using bafilomycin A1 hampers the infection, as the fusion is inhibited; instead, the virus is transported to late compartments where it undergoes proteolytic degradation. The degradation products are ejected from the cell via slow recycling vesicles. Surprisingly, NH 4 Cl, which is also believed to block endosome acidification, shows a very different mode of action. In the presence of this basic compound, the endocytic hub is reprogrammed. Zika virus-containing vesicles never reach the late stage, but are rapidly trafficked to the plasma membrane via a fast recycling pathway after the clathrin-mediated endocytosis. Further, we also noted that, similarly as other members of the flaviviridae family, Zika virus undergoes furin- or furin-like-dependent activation during late steps of infection, while serine or cysteine proteases are not required for Zika virus maturation or entry. Conclusions Zika virus fusion occurs in late endosomes and is pH-dependent. These results broaden our understanding of Zika virus intracellular trafficking and may in future allow for development of novel treatment strategies. Further, we identified a novel mode of action for agents commonly used in studies of virus entry. Schematic representation of differences in ZIKV trafficking in the presence of Baf A1 and NH 4 Cl Electronic supplementary material The online version of this article (10.1186/s12964-019-0349-z) contains supplementary material, which is available to authorized users.

Characterization of Zika Virus Endocytic Pathways in Human Glioblastoma Cells

“…Furthermore, researches of ZIKV endocytosis have broadened our understanding of ZIKV intracellular trafficking in clathrin-mediated endocytosis. ZIKV fusion occurs in late endosomes (Owczarek et al, 2019). It has been increasingly appreciated that many viruses can utilize more than one entryway to infect cells (Kalia et al, 2013;Yang et al, 2013).…”

Beyond the Surface: Endocytosis of Mosquito-Borne Flaviviruses

“…DENV-2 NGC and DENV-3 H87 infection of Vero cells has been previously reported to occur via a clathrin-independent but dynamin-dependent mechanism [ 171 , 172 ]. In general, ZIKV appears to be dependent on CME across divergent strains in diverse cell types [ 173 , 174 ], although a study in neural cells suggested a weak dependence [ 146 ]. Similarly, JEV was reported to infect neuronal cell lineages via a clathrin-independent pathway [ 175 , 176 , 177 ] in contrast to the clathrin-dependent endocytic mechanisms displayed in Vero, C6/36, BHK-21, HeLa and PK15 cells [ 178 , 179 , 180 , 181 , 182 ].…”

Amyloid precursor protein is a restriction factor that protects against Zika virus infection in mammalian brains

“…The P2 peptide is a water-soluble molecule but could not enhance APP expression when treating cells directly (data not shown). It is known that the interactions between BACE1 and APP protein happen in both biosynthetic and endocytic compartments inside cells (60,61), and ZIKV E protein was predicted to bind targets in the endosomal compartments (62,63). Therefore, we transfected P2 peptide into cells to ensure the peptide could meet APP in endocytic compartments physically.…”