This document summarizes research on how the Aedes aegypti mosquito regulates genes in ways that impact the spread of dengue virus. It finds that downregulated genes in the mosquito inhibit viral infection, while upregulated genes activate the mosquito's Toll immune pathway and also regulate other genes involved in viral replication. Specifically, it identifies genes for pupal cuticle protein and matrix metalloprotease that strongly inhibit flaviviruses when overexpressed in mosquitoes. The document also reviews dengue virus structure and life cycle, including its four serotypes, transmission from mosquito to humans, and how antibody-dependent enhancement can increase disease severity upon secondary infection.

1. STACY JACOBS (GROUP 1)
Aedes aegypti’s Regulation of Genes Impact
the Spread of Dengue Infections Through
Alterations to Dengue Virus
Replication/TransmissionA

2. Overview
Group 3 Group 2 Group 1 Group 4
• Aedes aegypti
• Life Cycle
-Adult
-Aquatic
• Morphology
• wMelPop
• Histology
• Transmission of
Dengue
-Mouth to
midgut
-Midgut to
hemocoel
-Hemocoel to
all organs
-Salivary
Glands
• Transcription
• Translation
• Dengue Virus
Replication
• ADE
• Genes
• Toll Pathway
• Habitat
-Temperature
-Location
• Keystone
Species
• Trophic Levels
• Prevention
Methods

3. B

4. Gene Expression – Transcription3,C
DNA ->
RNA
Polymerase
-> mRNA

5. Gene Expression – Translation3,H
mRNA -> Protein

6. Virus4,J
 Composed mainly of
RNA/DNA
 Enclosed in a protein shell
 Hijack cellular machinery
of host cells
 Inject genetic material into
host cells
 Structural rearrangement
of the viral protein coat

7. Dengue Virus4,D
 Enveloped positive strand RNA virus
 Structural Proteins
-Capsid (C) Protein
-Membrane (M) Protein
-Envelope (E) Protein
 Viral envelope surrounds the nucleocapsid
 E and M proteins attach to viral envelope

8. Dengue Virus Serotypes2,4,I
 Four Serotypes:
DENV 1, 2, 3, & 4
 Genetic variation
within serotypes due
to difference in
antigens

9. Dengue Virus Serotypes2,4
 Provides specific lifetime immunity and
short-term cross-immunity
 Some genetic variants within each
serotype may be more virulent or have
greater epidemic potential
 Bangkok, Thailand: 1994-2006
-DENV-1: more common
-DENV-2: more virulent

10. Dengue E Protein Dimer4
 Domain I = red
 Domain II = yellow
 Domain III = blue
 Acidic pH -> fusion peptides (in green) are exposed
to target membrane
 Domain III folds toward the fusion peptides
 Forcing the target membrane and viral membrane to
bend toward each other and fuse

11. G

12. Dengue Virus Transmission4,E
 Clatherin-mediated
endocytosis
 Nucleocapsid is
uncoated
 RNA is translated and
folded
 New RNA is packaged
into a nucleocapsid

13. Dengue Virus Transmission4,E
• Nucleocapsid enters
the ER -> translates
proteins; budding
occurs
• Nucleocapsid enters
the Golgi -> furin
cleavage
• Immature virus
matures and exits the
cell via exocytosis

14. Dengue Virus Transmission K

15. Antibody-Dependent Enhancement4,G
 Antibodies direct the
virus to Fc receptors
 Binds to the antigen
binding site
 Infects macrophages,
monocytes, dendritic
cells

16. Antibody-Dependent Enhancement3,G
 One serotype infects an
individual; later
another serotype
infects the same
individual
 Results in higher
viremia
 Secondary infections
tend to cause more
severe symptoms

17. Aedes aegypti’s Genome Map5
 1,376 Mb
 Four Quantitative
Trait Locis
(QTLs) related to
the transmission
of dengue
encompassed 11%
of chromosome 2

18. Regulation of Genes1
 Differentially Up-Regulated Genes (DURGs):
when a cell is deficient, more receptor protein is
synthesized
 Differentially Down-Regulated Genes
(DDRGs): when a cell is overstimulated, the
expression of the receptor protein is decreased

19. Results – DDRGs1
 AAEL011045 gene Pupal
Cuticle (PC) Protein
 AAEL003012 gene Matrix
Metalloprotease (MMP) for zinc
 Overexpression causes
flaviviruses to be inhibited one
million fold in mosquitoes

20. Results – DDRGs1
 PC Protein binds E protein on a virus -> inhibits
infection in mosquitoes and mice
 MMP inhibits infection in mosquitoes, but not in
mice

21. Results – DURG1
 AAEL014440 gene Juvenile Hormone
Inducible Protein
- up-regulated at all time points for all flaviviruses
- regulates many other genes
 AAEL003685 gene Core Histone H3 Protein
- 4 fold up-regulated at all time points for all
flaviviruses

22. Toll Pathway6,F

23. Toll Pathway6
 Uses a large number of DDRGs and DURGs that
function in immune response
-34.5% in midgut
-27.5% in carcass
 Myeloid Differentiation Primary Response gene 88
(MYD88) Cytoplasmic Adaptor Protein
 Cytoplasmic Adaptor Protein binds to a receptor ->
activates Toll Pathway

24. Toll Pathway6
 When MYD88 is silenced,
Toll Pathway is repressed.
 Therefore, dengue has
higher rates of infection.
 When the Cactus gene is
activated, the Toll Pathway
is stopped.

25. Concluding Remarks
 Dengue Infection can be controlled by:
- Alteration to Dengue Replication and
Transmission -> Change in pH, Antibody
Dependent Enhancement (ADE)
- Overexpression of DDRGs in A. aegypti
- MYD88 expression to activate Toll
Pathway
- Inhibition of Cactus does not stop Toll
Pathway

26. Works Cited - Literature
1. Colpitts, T., Cox, J., Vanlandingham, D., Feitosa, F., Cheng, G., Kurscheid, S., Wang, P.,
Krishnan, M., Higgs, S. and Firkrig, E. 2011. Alterations in the Aedes aegypti
transcriptome during infection with West Nile, dengue and yellow fever
viruses. PLoS Pathogens 7, e1002189.
2. Fried, J., Gibbons, R., Kalayanarooj, S., Thomas, S., Srikiatkhachorn, A., Yoon, I-K.,
Jarman, R., Green, S., Rothman, A. and Cummings, D. 2010. Serotype-specific
differences in the risk of dengue hemorrhagic fever: An analysis of data
collected in Bangkok, Thailand from 1994 to 2006. PLoS Neglected Tropical
Diseases 4, e617.
3. Grandi, G. 2007. In vitro transcription and translation protocols. Totoway, NJ.
Humana Press.
4. Rodenhuis-Zybert, I., Wilschut, J. and Smit, J. 2010. Dengue virus life cycle: viral and
host factors modulating infectivity. Cellular and Molecular Life Sciences 67,
2773-2786.
5. Timoshevskiy, V., Severson, D., deBruyn, B., Black, W., Sharakhov, I. and Sharakhov,
M. 2013. An integrated linkage, chromosome, and genome map for the yellow
fever mosquito Aedes aegypti. PLoS Neglected Tropical Diseases 7, e2052.
6. Zhiyong, X., Ramirez, J. and Dimopoulos G. 2008. The Aedes aegypti Toll pathway
controls dengue virus infection. PLoS Pathogens 4, e1000098.

27. Works Cited - Images
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guide
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D. http://www.nature.com/scitable/topicpage/dengue-viruses-22400925
E.http://pic1.gophoto.us/key/dengue%20virus%20life%20cycle%20ppt
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G.http://www.niaid.nih.gov/labsandresources/labs/aboutlabs/lvd/viralpathog
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H.http://pioneerbiology.wordpress.com/2010/10/24/transcriptiontransation/
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ml
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