Arboviruses and their Vectors
Curated by Journal of General Virology Editor Dr Eng Eong Ooi (Duke NUS Medical School) and Advisory Board Member Dr Esther Schnettler (Bernhard Nocht Institute for Tropical Medicine), this collection presents the latest advances in arbovirus research. This collection was launched in conjuction with IMAV 2017 and in line with IMAV 2019 welcomes submissions of original research articles, Insight Reviews and full-length Reviews.
Find out more about how to submit to the collection here.
Collection Contents
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The dengue virus non-structural protein 1 (NS1) is secreted from infected mosquito cells via a non-classical caveolin-1-dependent pathway
More LessDengue virus NS1 is a glycoprotein of 46–50 kDa that is conserved among flaviviruses, associates as a dimer to cell membranes and is secreted as a hexamer to the extracellular milieu. Recent evidence showed that NS1 is secreted efficiently from infected mosquito cells. To explore the secretory route of NS1 in mosquito cells, infected cells were treated with brefeldin A (BFA) and methyl-beta-cyclodextrin (MβCD). The results showed that MβCD, but not BFA, significantly reduced the release of NS1. Moreover, silencing the expression of caveolin-1 (CAV1; a key component of the caveolar system that transports cholesterol inside the cell), but not SAR1 (a GTPase that participates in the classical secretory pathway), also results in a significant reduction of the secretion of NS1. These results indicate that NS1 is released from mosquito cells via an unconventional secretory route that bypasses the Golgi complex, with the participation of CAV1. In agreement with this notion, differences were observed in the glycosylation status between secreted NS1 and E proteins. Classical mechanics and docking simulations suggested highly favoured interactions between the caveolin-binding domain present in NS1 and the scaffolding domain of CAV1. Finally, proximity ligation assays showed direct interaction between NS1 and CAV1 in infected mosquito cells. These findings are in line with the lipoprotein nature of secreted NS1 and provide new insights into the biology of NS1.
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Differences in the growth properties of Zika virus foetal brain isolate and related epidemic strains in vitro
More LessZika virus (ZIKV) has recently emerged into new areas in the Americas and Asia, causing an epidemic characterized by severe congenital infections. While ZIKV infection is usually asymptomatic or causes mild symptoms, it has now caused a high rate of foetal brain and ocular abnormalities. The underlying reasons for the varying severity of disease outcomes is poorly understood. In this study, we compared the infectivity and replication of three disease-associated Zika viruses of Asian lineage, as well as the prototypic ZIKV strain from Africa. The recent foetal brain isolate FB-GWUH-2016 demonstrated enhanced infectivity and replication over the serum-origin isolates from French Polynesia and Martinique, suggesting differences in the pathogenic properties.
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Deep sequencing analysis of tick-borne encephalitis virus from questing ticks at natural foci reveals similarities between quasispecies pools of the virus
More LessEvery year, tick-borne encephalitis virus (TBEV) causes severe central nervous system infection in 10 000 to 15 000 people in Europe and Asia. TBEV is maintained in the environment by an enzootic cycle that requires a tick vector and a vertebrate host, and the adaptation of TBEV to vertebrate and invertebrate environments is essential for TBEV persistence in nature. This adaptation is facilitated by the error-prone nature of the virus’s RNA-dependent RNA polymerase, which generates genetically distinct virus variants called quasispecies. TBEV shows a focal geographical distribution pattern where each focus represents a TBEV hotspot. Here, we sequenced and characterized two TBEV genomes, JP-296 and JP-554, from questing Ixodes ricinus ticks at a TBEV focus in central Sweden. Phylogenetic analysis showed geographical clustering among the newly sequenced strains and three previously sequenced Scandinavian strains, Toro-2003, Saringe-2009 and Mandal-2009, which originated from the same ancestor. Among these five Scandinavian TBEV strains, only Mandal-2009 showed a large deletion within the 3′ non-coding region (NCR), similar to the highly virulent TBEV strain Hypr. Deep sequencing of JP-296, JP-554 and Mandal-2009 revealed significantly high quasispecies diversity for JP-296 and JP-554, with intact 3′NCRs, compared to the low diversity in Mandal-2009, with a truncated 3′NCR. Single-nucleotide polymorphism analysis showed that 40 % of the single-nucleotide polymorphisms were common between quasispecies populations of JP-296 and JP-554, indicating a putative mechanism for how TBEV persists and is maintained within its natural foci.
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Dengue tropism for macrophages and dendritic cells: the host cell effect
More LessDengue virus infects immune cells, including monocytes, macrophages and dendritic cells (DC). We compared virus infectivity in macrophages and DC, and found that the virus origin determined the cell tropism of progeny virus. The highest efficiency of re-infection was seen for macrophage-derived dengue virus. Furthermore, in the presence of enhancing antibodies, macrophage-derived virus gave greater enhancement of infection compared with immature DC-derived virus. Taken together, our results highlight the importance of macrophages in dengue infection.
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