Production of an anti-dermatophyte monoclonal antibody and its application: immunochromatographic detection of dermatophytes

Tinea refers to superficial infection with one of three fungal genera—Microsporum, Epidermophyton, or Trichophyton—that are collectively known as dermatophytes. These infections are among the most common diseases worldwide and cause chronic morbidity. They are usually diagnosed by direct microscopy and fungal culture, which are burdensome to perform in the clinical setting. To supplement conventional methods, we developed a new method that employs an immunochromatography test for detection of dermatophyte infections. First, anti-Trichophyton monoclonal antibodies (mAb) were produced in mice using a Trichophyton allergen solution as an immunogen. The mAb specificity was assessed by immunostaining alcohol fixed slide cultures and formalin fixed paraffin-embedded microbial samples. Both alcohol- and formalin-fixed samples of all seven species of Trichophyton tested displayed positive immunostaining. Immunochromatography test strips were created using the anti-Trichophyton mAb. The efficiency of the test strip was assessed in patients diagnosed with tinea unguium and in healthy volunteers. Of the 20 patient nails tested, 19 tested positive and one tested negative, whereas of the 17 volunteer nails, only one tested positive. However, KOH microscopic examination of the volunteer nail that tested positive revealed the existence of Trichophyton hyphae. Although the number of nails assayed was small, since the assay had a sensitivity of 95.0% (19/20) and a specificity of 94.1% (16/17), the obtained results were considered to be promising. Thus, while further investigation with a greater number of samples is necessary, this method could potentially be employed as a new diagnostic tool for Trichophyton in the future.