A new assay for the detection of Loxosceles species (brown recluse) spider venom.
OBJECTIVE
Dermal lesions from unrelated arthropod species and medical causes appear similar to Loxosceles species (brown recluse spider) bites. This may result in delayed diagnosis and treatment. We developed a sensitive Loxosceles species venom enzyme-linked immunosorbent assay (ELISA) and characterized the specificity of the assay by evaluating antigenic cross-reactivity from a variety of North American arthropod venoms.


METHODS
North American arthropod (14 spiders, 2 scorpions, and 1 bee) venoms were studied. Three venom amounts (diluted in 100 microL of ELISA buffer) were assayed: 16,000 ng, 2,000 ng, and 40 ng. The latter quantity was selected because this is the observed maximum amount of venom we detect when inoculating dermis with amounts likely to be deposited by a spider bite. The larger venom amounts are overwhelming quantities designed to test the limits of the assay for arthropod venom cross-reactivity. Similar amounts of Loxosceles species venom and bovine albumin served as positive and negative controls, respectively.


RESULTS
At the lowest amount of venom tested (40 ng), the ELISA detected only the Loxosceles species positive control. When 2,000 ng was assayed, only Scytodes fusca and Kukulcania hibernalis arachnid venoms (in addition to Loxosceles species) cross-reacted to the assay. Finally, at 16,000 ng, the ELISA assay modestly detected Diguetia canities, Heteropoda venatoria, Tegenaria agrestis, Plectreurys tristes, Dolomedes tenebrosus, and Hadrurus arizonensis arachnid venoms.


CONCLUSIONS
Cross-reactivity was observed in 8 of 17 North American arthropod venoms when large venom amounts were assayed with a Loxosceles species ELISA. By using a relevant quantity of venom, 40 ng, the assay was specific for Loxosceles species venom. The venom specificity of the ELISA may allow clinical application in Loxosceles species endemic regions of North America.
Gomez
Hernan F
HF
Department of Emergency Medicine, University of Michigan Medical Center, Ann Arbor, MI 48109-0305, USA. hfg@umich.edu
Krywko
Diann M
DM
Stoecker
William V
WV
D000818:Animals; D001706:Biopsy; D002852:Chromatography, Ion Exchange; D003429:Cross Reactions; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D011817:Rabbits; D012680:Sensitivity and Specificity; D012867:Skin / Q000473:pathology; D001098:Spider Bites / Q000175:diagnosis* / Q000473:pathology; D013111:Spider Venoms / Q000032:analysis*; D013112:Spiders
D013111:Spider Venoms