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

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.

• 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.