Development of a Skin Test for the Na-ASP-2 Hookworm Antigen

January 18, 2012 updated by: Albert B. Sabin Vaccine Institute

Development of a Skin Test to Detect Immediate-type Hypersensitivity to the Experimental Na-ASP-2 Hookworm Antigen

Na-ASP-2 is a protein expressed during the larval stage of the N. americanus hookworm life cycle. In a clinical study in previously hookworm-infected adults in Brazil, this protein induced urticarial reactions (rash) in a subset of volunteers. This study will evaluate solutions of varying concentrations of the protein in both a skin prick-puncture and intradermal test that will eventually be used to screen volunteers living in hookworm endemic areas who are being considered as potential participants in vaccine trials, to reduce the potential of inducing allergic reactions in those vaccinated with the Na-ASP-2 Hookworm Vaccine.

Study Overview

Status

Completed

Detailed Description

  • Study site: George Washington University Medical Center
  • Number of participants: up to 15
  • Study duration: up to 3 months; each participant will undergo a minimum of one screening visit and one study visit.
  • Each participant will have both skin prick-puncture and intradermal skin tests applied on the same study day. The prick-puncture and intradermal tests will be applied sequentially to the volar aspects of the participant's forearms:

    1. Skin prick-puncture: four different concentrations of Na-ASP-2 solution (1, 10, 100, and 1000 μg/mL) will be applied simultaneously in duplicate, to the left forearm.
    2. Intradermal: three different concentrations of Na-ASP-2 (10, 100, and 1000 μg/mL) will be injected simultaneously, in duplicate, to the right forearm.
    3. Allergen diluent and histamine solutions will be utilized as the negative and positive controls, respectively, for both the skin prick-puncture and intradermal tests.
    4. Participants will be observed in the study clinic for at least 30 minutes following application of the skin tests, and will be contacted via telephone 2 days following skin testing.
    5. Sizes of the wheal and erythema reactions for each application will be recorded and graded in comparison to the histamine positive control reaction.
  • Each participant will have blood collected via venipuncture (a maximum of 25 mL) immediately prior to application of the skin tests, in order to measure antibodies (particularly IgG and IgE) to Na-ASP-2 using an ELISA procedure.

Study Type

Interventional

Enrollment (Actual)

12

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • District of Columbia
      • Washington, District of Columbia, United States, 20037
        • GWUMC Clinical Trials Unit

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 45 years (ADULT)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Males or females between 18 and 45 years of age, inclusive.
  • Good general health as determined by means of the screening procedure.
  • Willingness to participate in the study as evidenced by signing the informed consent document.

Exclusion Criteria:

  • History of previous infection with hookworm.
  • Prior extensive and continuous travel, work, or residence (> 1 month) in a hookworm-endemic region.
  • Pregnancy as determined by a positive urine hCG test (if female).
  • Evidence of clinically significant neurologic, cardiac, pulmonary, hepatic, rheumatologic, autoimmune, or renal disease by history or physical examination.
  • Behavioral, cognitive, or psychiatric disease that in the opinion of the investigator affects the ability of the volunteer to understand and cooperate with the study protocol.
  • Other condition that in the opinion of the investigator would jeopardize the safety or rights of a volunteer participating in the trial or would render the subject unable to comply with the protocol.
  • Participation in an investigational vaccine or drug trial within 14 days of starting this study.
  • Volunteer has had medical, occupational, or family problems as a result of alcohol or illicit drug use during the past 12 months.
  • History of a severe allergic reaction or anaphylaxis.
  • Known immunodeficiency syndrome.
  • Use of corticosteroids (excluding topical or nasal) or immunosuppressive drugs within 30 days of starting this study.
  • History of a surgical splenectomy.
  • Extensive dermatitis precluding skin testing
  • Current use of a beta blocker (oral or topical) or anti-histamine medication. A volunteer may participate in the study if they agree to withhold use of an anti-histamine for at least 5 days prior to application of the skin test.
  • Use of a tricyclic anti-depressant within the past month.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: DIAGNOSTIC
  • Allocation: NA
  • Interventional Model: SINGLE_GROUP
  • Masking: NONE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
EXPERIMENTAL: Na-ASP-2 Hookworm Antigen Skin Test
All participants will have the same number of concentrations of the Na-ASP-2 skin test reagent applied to their arms, using both the prick-puncture and intradermal techniques.
Na-ASP-2 Hookworm Skin Test Reagent, 1-1000 mcg/mL solution

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
100 Mcg/ml Na-ASP-2 Prick-puncture Skin Test
Time Frame: 15 minutes after skin test application

Mean grade of wheal reaction after 2 applications of the skin test reagent per participant. For each skin test reaction, the grade of the test was determined based on the mean of the longest and orthogonal diameters, which was then compared to the equivalent measurements of a histamine solution positive control that was applied at the same time as the test. Grading was as follows:

0 no discernible wheal

  1. < ½ histamine diameter
  2. ≥ ½ histamine; < histamine diameter
  3. = size of histamine control ± 1 mm
  4. > histamine diameter; < 2x diameter
  5. ≥ 2x histamine control
15 minutes after skin test application

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
1000 Mcg/ml Na-ASP-2 Prick-puncture Skin Test
Time Frame: 15 minutes after skin test application

Mean grade of wheal reaction after 2 applications of the skin test reagent per participant. For each skin test reaction, the grade of the test was determined based on the mean of the longest and orthogonal diameters, which was then compared to the equivalent measurements of a histamine solution positive control that was applied at the same time as the test. Grading was as follows:

0 no discernible wheal

  1. < ½ histamine diameter
  2. ≥ ½ histamine; < histamine diameter
  3. = size of histamine control ± 1 mm
  4. > histamine diameter; < 2x diameter
  5. ≥ 2x histamine control
15 minutes after skin test application
100 Mcg/ml Na-ASP-2 Intradermal Skin Test
Time Frame: 15 minutes after skin test application

Mean grade of wheal reaction after 2 applications of the skin test reagent per participant. For each skin test reaction, the grade of the test was determined based on the mean of the longest and orthogonal diameters, which was then compared to the equivalent measurements of a histamine solution positive control that was applied at the same time as the test. Grading was as follows:

0 no discernible wheal

  1. < ½ histamine diameter
  2. ≥ ½ histamine; < histamine diameter
  3. = size of histamine control ± 1 mm
  4. > histamine diameter; < 2x diameter
  5. ≥ 2x histamine control
15 minutes after skin test application
1000 Mcg/ml Na-ASP-2 Intradermal Skin Test
Time Frame: 15 minutes after skin test application

Mean grade of wheal reaction after 2 applications of the skin test reagent per participant. For each skin test reaction, the grade of the test was determined based on the mean of the longest and orthogonal diameters, which was then compared to the equivalent measurements of a histamine solution positive control that was applied at the same time as the test. Grading was as follows:

0 no discernible wheal

  1. < ½ histamine diameter
  2. ≥ ½ histamine; < histamine diameter
  3. = size of histamine control ± 1 mm
  4. > histamine diameter; < 2x diameter
  5. ≥ 2x histamine control
15 minutes after skin test application

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Investigators

  • Principal Investigator: David Parenti, MD, GWUMC Medical Faculty Associates

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

March 1, 2008

Primary Completion (ACTUAL)

May 1, 2008

Study Completion (ACTUAL)

May 1, 2008

Study Registration Dates

First Submitted

January 17, 2008

First Submitted That Met QC Criteria

January 28, 2008

First Posted (ESTIMATE)

January 29, 2008

Study Record Updates

Last Update Posted (ESTIMATE)

February 23, 2012

Last Update Submitted That Met QC Criteria

January 18, 2012

Last Verified

January 1, 2012

More Information

Terms related to this study

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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