Additive protection by antioxidant and apoptosis-inhibiting effects on mosquito cells with dengue 2 virus infection.
PLoS Negl Trop Dis 2012;
6:e1613. [PMID:
22530071 PMCID:
PMC3328429 DOI:
10.1371/journal.pntd.0001613]
[Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Accepted: 02/27/2012] [Indexed: 01/18/2023] Open
Abstract
Cytopathic effects (CPEs) in mosquito cells are generally trivial compared to those that occur in mammalian cells, which usually end up undergoing apoptosis during dengue virus (DENV) infection. However, oxidative stress was detected in both types of infected cells. Despite this, the survival of mosquito cells benefits from the upregulation of genes related to antioxidant defense, such as glutathione S transferase (GST). A second defense system, i.e., consisting of antiapoptotic effects, was also shown to play a role in protecting mosquito cells against DENV infection. This system is regulated by an inhibitor of apoptosis (IAP) that is an upstream regulator of caspases-9 and -3. DENV-infected C6/36 cells with double knockdown of GST and the IAP showed a synergistic effect on activation of these two caspases, causing a higher rate of apoptosis (>20%) than those with knockdown of each single gene (∼10%). It seems that the IAP acts as a second line of defense with an additional effect on the survival of mosquito cells with DENV infection. Compared to mammalian cells, residual hydrogen peroxide in DENV-infected C6/36 cells may signal for upregulation of the IAP. This novel finding sheds light on virus/cell interactions and their coevolution that may elucidate how mosquitoes can be a vector of DENV and probably most other arboviruses in nature.
This study demonstrated an idea that mosquito cells can survive dengue virus (or other arboviruses) infection through antioxidant defense and an additional effect by induction of IAP expression for protection of infection. It makes mosquito eligible to support virus replication efficiently, leading to a goal which is important to explain how mosquitoes can be a vector even when they have been seriously infected by the virus. Our findings opened an avenue for studies on virus/vector co-evolution that benefits for both virus replication and its transmission to humans or susceptible hosts.
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