Characterization of Skin Immunity to Aedes Aegypti Saliva in Dengue-endemic Participants in Cambodia
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|ClinicalTrials.gov Identifier: NCT04350905|
Recruitment Status : Completed
First Posted : April 17, 2020
Results First Posted : April 12, 2022
Last Update Posted : April 12, 2022
Mosquito-borne viruses like dengue cause major illness and death worldwide, particularly in Southeast Asia. When mosquitoes deliver a virus into the skin of humans, they also leave saliva. Researchers want to learn more about skin immunity to mosquito saliva. They hope this will help with future vaccines and treatments for these diseases.
To compare the early and late innate immune response in the skin of Aedes aegypti bitten versus unbitten skin.
Healthy people ages 18-45 who live within about 15 km of the study site in Chbar Mon
Participants will have 3 visits.
The baseline/screening visit will include:
Medical and medication history
Questions about participants demographic information, mosquito biting risk factors, and responses to mosquito or other insect bites
Urine sample for some participants
Mosquito feeding. A feeding device will be placed on the participant s arm for up to 20 minutes. The insects will feed through a mesh on the bottom of the feeding device. Participants may be given standard treatments for any skin reactions.
Four skin biopsies taken from bitten and unbitten skin. Local anesthetic will be administered, and a small tool will be used to remove the participant s skin.
Participants will have a second visit the next day. They will have a physical exam and blood tests. They will have 1 skin biopsy.
Participants will have a final visit about 2 weeks later. They will have a physical exam and blood tests.
During the study, participants will be asked to take measures to prevent more mosquito bites.
|Condition or disease||Intervention/treatment||Phase|
|Vector Borne Diseases||Other: Mosquito Feeding||Phase 1|
Mosquito-borne viruses continue to cause significant global morbidity and mortality, particularly in Southeast Asia. When mosquitoes deliver the virus into the skin of humans while probing for a blood meal, they deposit also saliva, which contains a myriad of pharmacologically active compounds that modulate the host immune system. Little is known about skin immunity to mosquito saliva, particularly in endemic volunteers as most clinical studies are performed in na(SqrRoot) ve individuals who have never or rarely been exposed to a particular mosquito vector. People living in endemic areas have had long-term repeated exposure to these vectors and therefore have different immune response to mosquito saliva, which could interfere with mosquito-borne disease vaccine effectiveness. Characterization of skin immunity via various technical modalities will be important in order to identify critical aspects of the innate and adaptive immune responses after a vector bite.
Here, we will execute a paired study of exposed-unexposed skin to carefully examine the innate and adaptive immune responses in the skin and blood to exposure of the saliva of Aedes aegypti, the mosquito vector of dengue, Zika, and chikungunya viruses. We will enroll 42 participants to undergo vector feeding and give blood samples at baseline and 2 and 14 days later. Additionally, participants will give skin punch biopsy samples of bitten (exposed) and unbitten (unexposed) skin. For analysis, we will group 10-12 participants in each of 4 technical modality cohorts or groups : 1) immunohistochemistry, 2) RNA sequencing, 3) flow cytometry, and 4) T-cell receptor sequencing. With the current rise of vector-borne diseases in the United States and around the world, we hope the results of this study contribute to future vaccine design and clinical development strategies for vector#borne diseases.
|Study Type :||Interventional (Clinical Trial)|
|Actual Enrollment :||42 participants|
|Intervention Model:||Single Group Assignment|
|Intervention Model Description:||Participants were all exposed to 5 uninfected Aedes aegypti mosquitos on their forearm. Biopsies were taken of bitten and unbitten skin.|
|Masking:||None (Open Label)|
|Primary Purpose:||Basic Science|
|Official Title:||Characterization of Skin Immunity to Aedes Aegypti Saliva in Dengue-Endemic Participants in Cambodia|
|Actual Study Start Date :||October 27, 2020|
|Actual Primary Completion Date :||April 9, 2021|
|Actual Study Completion Date :||April 9, 2021|
Experimental: Mosquito Feeding
Each participant will receive one mosquito feeding with 5 starved female Aedes aegypti mosquitoes.
Other: Mosquito Feeding
Mosquito feedings will be conducted with Aedes aegypti colonies raised at the CNM (National Malaria Center) Malaria and Vector Research Laboratory (MVRL), an established state of the art insectaries for mosquitoes was built in 2014 to ACL2 (arthropodcontainment level 2)-level specifications.
- Measurement of Change in Early and Late Innate Immune Responses Using Gene Expression and Flow Cytometry in Participants' Skin [ Time Frame: Day 0 timepoints ]Measurement of changes in the early and late innate immune response and cellular recruitment in bitten skin versus unbitten skin by: a) immunohistochemistry of target proteins at Day 0 timepoints b) immunophenotyping of innate immune cell subsets in dissociated skin sample at Day 0 timepoints c) determination of cytokine profile in dissociated skin sample supernatant at Day 0 timepoints d) differential cDNA expression prepared from skin RNA and analyzed via RNASeq at Day 0 timepoints
- Measurement of Changes in the Adaptive Immune Response and Cellular Recruitment in the Skin of Bitten Versus Unbitten Skin After Sixth and Final Feeding in Each Vector Group. [ Time Frame: Day 2 (48 hr post feeding) ]Measurement of changes in the adaptive immune response and cellular recruitment in bitten skin versus unbitten skin by: a) immunohistochemistry of target proteins at Day 2 timepoints b) phenotyping of adaptive immune cell subsets in dissociated skin sample at Day 2 timepoints c) determination of cytokine profile in dissociated skin sample supernatant at Day 2 timepoints d) differential cDNA expression prepared from skin RNA and analyzed via RNASeq at Day 2 timepoints
- Flow Cytometry Analysis of PBMCs Collected Day 0 (Baseline) and Days 2 and 14 After Feeding for Saliva-specific T-cells [ Time Frame: Day 14 ]Describing and understanding cellular immunity to Aedes saliva in heavily exposed individuals will simulate endemic conditions and will inform vaccine design in these target populations.
To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04350905
|Kampong Speu Referral Hoispital|
|Chbar Mon, Cambodia, 05251|
|Principal Investigator:||Jessica E Manning, M.D.||National Institute of Allergy and Infectious Diseases (NIAID)|