Group 1 Presentation

STACY JACOBS (GROUP 1)

Aedes aegypti’s Regulation of Genes Impact the Spread of Dengue Infections

Through Alterations to Dengue Virus Replication/TransmissionA

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

B

Gene Expression – Transcription3,C

DNA -> RNA

Polymerase ->

mRNA

Gene Expression – Translation3,H

mRNA -> Protein

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

Dengue Virus4,D

Enveloped positive strand RNA virusStructural Proteins -Capsid (C) Protein -Membrane (M) Protein -Envelope (E) Protein

Viral envelope surrounds the nucleocapsid E and M proteins attach to viral envelope

Dengue Virus Serotypes2,4,I

Four Serotypes: DENV 1, 2, 3, & 4

Genetic variation within serotypes due to difference in antigens

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

Dengue E Protein Dimer4

Domain I = redDomain II = yellowDomain III = blue

Acidic pH -> fusion peptides (in green) are exposed to target membrane

Domain III folds toward the fusion peptidesForcing the target membrane and viral

membrane to bend toward each other and fuse

G

Dengue Virus Transmission4,E

Clatherin-mediated endocytosis

Nucleocapsid is uncoated

RNA is translated and folded

New RNA is packaged into a nucleocapsid

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

Dengue Virus Transmission K

Antibody-Dependent Enhancement4,G

Antibodies direct the virus to Fc receptors

Binds to the antigen binding site

Infects macrophages, monocytes, dendritic cells

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

Aedes aegypti’s Genome Map5

1,376 Mb

Four Quantitative Trait Locis (QTLs) related to the transmission of dengue encompassed 11% of chromosome 2

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

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

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

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

Toll Pathway6,F

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

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.

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

Works Cited - Literature1. 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. 

Works Cited - ImagesA. http://www.nowpublic.com/health/aedes-aegypti-0B. http://hubpages.com/hub/protein-production-a-step-by-step-illustrated-guideC. http://denydendhi.blogspot.com/2011/03/replikasi-dna.htmlD. http://www.nature.com/scitable/topicpage/dengue-viruses-22400925E.http://pic1.gophoto.us/key/dengue%20virus%20life%20cycle%20pptF.http://www.pnas.org/content/109/1/E23/F6.expansion.htmlG.http://www.niaid.nih.gov/labsandresources/labs/aboutlabs/lvd/viralpathogenesissection/Pages/default.aspxH.http://pioneerbiology.wordpress.com/2010/10/24/transcriptiontransation/I.http://www.biology.arizona.edu/immunology/tutorials/antibody/structure.htmlJ. http://oceanworld.tamu.edu/resources/oceanography-book/microbialweb.htm