Immunoassay for venom detection including noninvasive sample collection
Inventors
Stoecker, William V. • Gomez, Hernan F. • Green, Jonathan A. • McGlasson, David L.
Assignees
Spidertech A Division Of Stoecker & Associates A Subsidiary Of Dermatology Center LLC • Stoecker and Associates LLC • University of Michigan Ann Arbor • University of Missouri Columbia • University of Missouri St Louis • United States Department of the Air Force
Publication Number
US-8426154-B2
Publication Date
2013-04-23
Expiration Date
2026-10-17
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Abstract
Methods and immunoassays for diagnosing a bite or sting of a venomous organism in a patient having symptoms consistent with such a bite or sting are provided. A sample of venom is collected from the area of the suspected bite or sting using a swab and then contacted with an antibody that specifically binds to an antigenic site on venom present in the sample. Binding is then detected. The invention is illustrated by examples showing diagnosis of brown recluse spider bite, distinguishing it from other diagnoses with which it is often confused. This extremely sensitive test can detect venom antigens down to about 20 picograms even after the sample has been shipped and stored for periods of up to three weeks during the summer.
Core Innovation
The invention provides methods and immunoassays for diagnosing a bite or sting of a venomous organism in a patient with symptoms consistent with such a bite or sting. It utilizes a swab to collect a sample comprising venom from the area of the suspected bite or sting. The sample is then contacted with an antibody specifically binding to an antigenic site on venom present in the sample, and binding is detected to confirm the presence of venom.
The invention addresses the challenges in diagnosing brown recluse spider bites, where clinical diagnosis is typically based on wound morphology due to the rarity of obtaining the actual spider. Existing serologic tests and antibody detection in humans are inadequate due to weak immune responses and lack of sensitivity. The assay overcomes these by detecting venom antigen directly from non-invasive samples, such as swabs of the bite area, with high sensitivity even after sample storage and shipping.
Claims Coverage
The patent includes one independent claim directed to a method for diagnosing a Loxosceles spider bite using sample collection, antibody binding, and detection steps. The inventive features focus on the sampling method, antibody specificity, detection technique, and assay sensitivity.
Method of diagnosing Loxosceles spider bite using swab sampling and antibody detection
A method involving collecting a venom-containing sample from the area of the bite using a swab, contacting the sample with an antibody that specifically binds Loxosceles venom, and detecting the complex formed between the antibody and venom with a tracer.
Use of diverse absorbent or adsorbent swab materials
The swab used to collect the venom sample can comprise materials including cotton, synthetic fibers, rayon, polyurethane foam, brushes, paper, and sponge.
Detection methods including sandwich immunoassays and electrochemical immunoassays
The antibody-venom binding detection can be carried out by sandwich immunoassays or electrochemical immunoassays, and can be performed outside a laboratory, including field immunoassay devices.
Swab comprising antibody and disposable use
In some methods, the swab itself comprises the antibody immobilized thereon and can be disposable for convenience and prevention of cross-contamination.
Controlled sample collection and exposure conditions
The sample collection may be performed by gently wiping or soaking the skin for about one to 360 seconds. The sample can be blister fluid and may be exposed to ambient summertime temperatures for up to about three weeks prior to detecting venom.
Use of modified ELISA with reduced blocking and enhanced sensitivity
The method can utilize an ELISA modified to reduce blocking antibodies using nonfat milk solids and alkaline phosphatase markers, capable of detecting under 24 picograms of venom in the sample, and distinguishing Loxosceles venom from other species venom.
The claims cover a sensitive and specific method for diagnosing Loxosceles spider bites using non-invasive swab sampling combined with antibody-based immunoassays and enhanced detection techniques, enabling field-applicable and precise venom identification even after sample storage or shipment.
Stated Advantages
Provides an extremely sensitive assay able to detect venom antigens down to about 20 picograms even after storage and shipping of samples for up to three weeks during summer temperatures.
Enables non-invasive sample collection using swabs from bite or sting sites, avoiding pain from cutting or needles, suitable for children and elderly patients.
Allows accurate diagnosis of Loxosceles envenomation, differentiating it from other medical conditions with similar skin presentations, preventing misdiagnosis and inappropriate treatment.
The assay can be performed outside a laboratory setting, facilitating field or clinical use for rapid diagnosis.
The method can distinguish the organism responsible for the bite or sting from other venomous species by using antibodies specific to particular venom proteins.
The techniques can be broadly applied to detection of other clinically relevant venom proteins or foreign proteins.
Documented Applications
Diagnosis of brown recluse spider (Loxosceles reclusa) bites in humans and animals using non-invasive swab sampling and ELISA.
Use in differentiating Loxosceles envenomation from other dermatological conditions with similar necrotic presentations.
Field or clinical immunoassay devices for rapid detection of venom presence after suspected bites or stings from various venomous organisms.
Application to envenomations from other venomous spiders of the genus Loxosceles, including Loxosceles intermedia, Loxosceles laeta, Loxosceles gaucho, and Loxosceles rufescens.
Potential extension to diagnosing bites or stings from venomous organisms such as wasps, bees, scorpions, snakes, and jellyfish using similar immunoassay approaches.
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