Anopheles gambiae and other insects utilize a variety of strategies to combat microbial invaders. The long-term goal of the PIs research is to characterize and understand the mechanisms of innate immunity used by the mosquito against microbes. This proposal focuses on the particular role of the Down syndrome cell adhesion molecule (Dscam) as a hypervariable immune surveillance receptor. Dscam's complex genomic organization and remarkable properties suggest that it plays multiple roles in immune defense: In A. gambiae, alternative splicing of the AgDscam gene produces >31,920 alternative splice- form receptors with different adhesive characteristics and specificities. AgDscam produces microbe-specific splice-form repertoires upon immune challenge and is involved in both antibacterial and anti-Plasmodium defense. The studies outlined here will further test the hypothesis that, as previously shown for challenge with a limited number of bacteria, this phenotypic plasticity of the AgDscam gene allows it to produce receptor molecules with potent antimicrobial activity and high affinity for bacteria and the Plasmodium parasite. To test this hypothesis, the proposed studies will use RNAi silencing, immunohistochemical staining, microarray analyses, and interaction analyses to determine (in Specific Aim 1) the regulation of AgDscam splicing and production of splice form repertoire by microbe challenge and the innate immune pathways, and (in Aims 2) the specific splice-form repertoires involved in these defenses and interactions with microbes. We will finally test the anti-Plasmodium defense specificity and efficacy of AgDscam in genetically modified mosquito lines that over-express pathogen specific splice forms (in Specific Aim 3). These analyses will elucidate one of the most remarkable players of the insect innate immune system, which allows it to cope with a broad spectrum of microbes through the microbe challenge specific production of pattern recognition receptors. The study will also assess the feasibility to use AgDscam for the generation of Plasmodium resistant mosquitoes that could be used for the development of a malaria control strategy.

Public Health Relevance

The Anopheles mosquito uses its innate immune system to fight against a broad spectrum of microbial pathogens including the Plasmodium parasite. This research proposal aims at the study of a hypervariable pattern recognition receptor, AgDscam, to understand its immune related regulation and assess its capacity to kill Plasmodium.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI081877-04
Application #
8462530
Study Section
Innate Immunity and Inflammation Study Section (III)
Program Officer
Costero, Adriana
Project Start
2010-06-01
Project End
2015-05-31
Budget Start
2013-06-01
Budget End
2014-05-31
Support Year
4
Fiscal Year
2013
Total Cost
$305,237
Indirect Cost
$119,117
Name
Johns Hopkins University
Department
Microbiology/Immun/Virology
Type
Schools of Public Health
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21218
Clayton, April M; Dong, Yuemei; Dimopoulos, George (2014) The Anopheles innate immune system in the defense against malaria infection. J Innate Immun 6:169-81
Cirimotich, Chris M; Ramirez, Jose L; Dimopoulos, George (2011) Native microbiota shape insect vector competence for human pathogens. Cell Host Microbe 10:307-10