Aedes aegypti uses RNA interference in defense against Sindbis virus infection

BMC Microbiol. 2008 Mar 17;8:47. doi: 10.1186/1471-2180-8-47.


Background: RNA interference (RNAi) is an important anti-viral defense mechanism. The Aedes aegypti genome encodes RNAi component orthologs, however, most populations of this mosquito are readily infected by, and subsequently transmit flaviviruses and alphaviruses. The goal of this study was to use Ae. aegypti as a model system to determine how the mosquito's anti-viral RNAi pathway interacts with recombinant Sindbis virus (SINV; family Togaviridae, genus Alphavirus).

Results: SINV (TR339-eGFP) (+) strand RNA, infectious virus titers and infection rates transiently increased in mosquitoes following dsRNA injection to cognate Ago2, Dcr2, or TSN mRNAs. Detection of SINV RNA-derived small RNAs at 2 and 7 days post-infection in non-silenced mosquitoes provided important confirmation of RNAi pathway activity. Two different recombinant SINV viruses (MRE16-eGFP and TR339-eGFP) with significant differences in infection kinetics were used to delineate vector/virus interactions in the midgut. We show virus-dependent effects on RNAi component transcript and protein levels during infection. Monitoring midgut Ago2, Dcr2, and TSN transcript levels during infection revealed that only TSN transcripts were significantly increased in midguts over blood-fed controls. Ago2 protein levels were depleted immediately following a non-infectious bloodmeal and varied during SINV infection in a virus-dependent manner.

Conclusion: We show that silencing RNAi components in Ae. aegypti results in transient increases in SINV replication. Furthermore, Ae. aegypti RNAi is active during SINV infection as indicated by production of virus-specific siRNAs. Lastly, the RNAi response varies in a virus-dependent manner. These data define important features of RNAi anti-viral defense in Ae. aegypti.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aedes / immunology*
  • Aedes / virology*
  • Alphavirus Infections / immunology*
  • Alphavirus Infections / prevention & control*
  • Animals
  • Argonaute Proteins
  • DNA-Binding Proteins / biosynthesis
  • DNA-Binding Proteins / genetics
  • Drosophila Proteins / biosynthesis
  • Drosophila Proteins / genetics
  • Gastrointestinal Tract / immunology
  • Gastrointestinal Tract / virology
  • Gene Expression Profiling
  • RNA Interference*
  • RNA, Small Interfering / biosynthesis
  • RNA-Induced Silencing Complex / biosynthesis
  • RNA-Induced Silencing Complex / genetics
  • Receptors, TNF-Related Apoptosis-Inducing Ligand / biosynthesis
  • Receptors, TNF-Related Apoptosis-Inducing Ligand / genetics
  • Sindbis Virus / immunology*
  • Survival Analysis


  • AGO2 protein, Drosophila
  • Argonaute Proteins
  • DNA-Binding Proteins
  • Drosophila Proteins
  • RNA, Small Interfering
  • RNA-Induced Silencing Complex
  • Receptors, TNF-Related Apoptosis-Inducing Ligand