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Characterization of Skin Immunity to Aedes Aegypti Saliva in Dengue-endemic Participants in Cambodia

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
 
ClinicalTrials.gov Identifier: NCT04350905
Recruitment Status : Completed
First Posted : April 17, 2020
Results First Posted : April 12, 2022
Last Update Posted : April 12, 2022
Sponsor:
Information provided by (Responsible Party):
National Institutes of Health Clinical Center (CC) ( National Institute of Allergy and Infectious Diseases (NIAID) )

Brief Summary:

Background:

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.

Objective:

To compare the early and late innate immune response in the skin of Aedes aegypti bitten versus unbitten skin.

Eligibility:

Healthy people ages 18-45 who live within about 15 km of the study site in Chbar Mon

Design:

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

Physical exam

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.

Blood tests

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

Detailed Description:

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.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 42 participants
Allocation: N/A
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

Resource links provided by the National Library of Medicine


Arm Intervention/treatment
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.




Primary Outcome Measures :
  1. 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

  2. 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


Secondary Outcome Measures :
  1. 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.



Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.


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Ages Eligible for Study:   18 Years to 45 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Criteria
  • INCLUSION CRITERIA:

In order to be eligible to participate in this study, an individual must meet all of the following criteria:

-Provision of signed and dated informed consent form

  • Stated willingness to comply with all study procedures and availability for the duration of the study
  • Male or female, aged 18 - 45 years
  • Live within approximately 15 km of study site
  • In good general health as evidenced by medical history
  • Willing to allow biological samples to be stored for future research.
  • A female is eligible for this study if she meets 1 of the following:

    • Of non-childbearing potential (i.e., women who have had a hysterectomy or tubal

ligation or are postmenopausal, as defined by no menses in >=1 year).

--Of childbearing potential but has negative urine pregnancy test on Day 0

  • Agrees to not use scented lotions, deodorants, or topical creams on each feeding day.
  • Agrees to not take aspirin or any other NSAID (ex. ibuprofen) within 7 days of a biopsy.
  • Agrees to not use oral or topical antihistamines or steroid creams or ointments throughout the

study without prior permission of Principal Investigator (PI).

EXCLUSION CRITERIA:

-Any underlying or current medical condition that, in the opinion of the investigator, would

interfere with participation in the study.

-History of severe allergic reaction (including to mosquito or other insect bites) with generalized

urticaria, angioedema, anaphylaxis, anaphylactoid reaction or any other reaction described by

the participant and deemed severe by the PI.

  • Self-reported or known history of alcoholism or drug abuse within 6 months prior to enrollment
  • Self-reported or known history of psychiatric or psychological issues that require treatment and

are deemed by the PI to be a contraindication to protocol participation.

-Any use of medications that affect blood clotting within 3 months or history of abnormal blood

clotting

-History of significant scarring such as keloids after previous biopsies, lacerations, abrasions,

surgeries, or other skin procedures (e.g., cosmetic piercings) that are deemed by the PI to be a

contraindication to protocol participation.

-Pregnant or breastfeeding.


Information from the National Library of Medicine

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


Locations
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Cambodia
Kampong Speu Referral Hoispital
Chbar Mon, Cambodia, 05251
Sponsors and Collaborators
National Institute of Allergy and Infectious Diseases (NIAID)
Investigators
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Principal Investigator: Jessica E Manning, M.D. National Institute of Allergy and Infectious Diseases (NIAID)
  Study Documents (Full-Text)

Documents provided by National Institutes of Health Clinical Center (CC) ( National Institute of Allergy and Infectious Diseases (NIAID) ):
Publications:
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Responsible Party: National Institute of Allergy and Infectious Diseases (NIAID)
ClinicalTrials.gov Identifier: NCT04350905    
Other Study ID Numbers: 999920053
20-I-N053
First Posted: April 17, 2020    Key Record Dates
Results First Posted: April 12, 2022
Last Update Posted: April 12, 2022
Last Verified: April 9, 2021

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Keywords provided by National Institutes of Health Clinical Center (CC) ( National Institute of Allergy and Infectious Diseases (NIAID) ):
Vector-Borne Diseases
Immune Response
Mosquito Feeding
Arbovirus
Southeast Asia
Additional relevant MeSH terms:
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Vector Borne Diseases
Infections