Ultrastructural studies on the replication cycle of dengue virus in C6/36 cells
| Autor: | Yin Ping Lo, 羅尹萍 |
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| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 Dengue virus is a member of the Genus flavivirus belonging to the family Flaviviridae which comprises a single-strained RNA genome of positive polarity. The morphology of virus is spherical, enveloped, and 50 nm (mature virion) or 60 nm (immature virion) in diameter. Dengue virus usually infects host cells via receptor-mediated endocytosis followed by the release of genomic RNA after uncoating of the nucleocapsid. A single polyprotein is translated, which is cleaved into 10 proteins in consequence, within the endoplasmic reticulum during the cycle of viral replication. It has been reported that flavivirus replication occurs in a virus-induced membrane structure. In addition, the replication was initiated by endocytosis of viral particles which were fused with endosomal membranes in the cytoplasm. However, its detail has not been observed and clearly interpreted thus far. In this study, the replication process of dengue virus was investigated in C6/36 mosquito cells by using transmission electron microscopy (TEM) as well as confocal laser microscopy. The results showed that dsRNAs appeared around perinuclear regions as early as 6 h post- infection. Subsequently, numerous viral particles formed as a crystalline array in and/or adjacent to a unique structure at 6, 12, or 24 h post-infection. Presumably, the structure containing newly-formed viral particles serves as a “viral factory” in which protein translation, RNA replication, and the early stage of virion assembly may occur. Virions containing nucleocapsid were usually seen at 24 h post- infection. It was likely that virions have appropriately modified during dispensing into vacuoles or vesicle packets. A mature virion is measured 45 nm in diameter, smaller than that (60 nm) from the crystalline array. The mature virions were then transported to the cell surface, i.e., intercellular space, probably via the host secretion system. It suggested that the virus could infect neighboring cells via cell-to-cell transmission which is supposed to be efficient for virus infection between cells. The increase of tetraspanin C189 in C6/36 cells with dengue 2 virus infection was previously identified in our laboratory. In this study, using the immunofluorescen staining, C189 and den-2 virus was further demonstrated colocalizing in the cytoplasm of infected C6/36 cells at 24 h post- infection. It is speculated that C189 participate in regulating assembly, maturation, and/or releasing during infection of the virus in mosquito cells. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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