Evaluation of Cross-Reactivity of Suidasia pontifica with Allergens Blo t 5 from the Blomia tropicalis Mite

Background: The immunological cross-reactivity between different species of dust mites such as Suidasia pontifica and Blomia tropicalis is a factor that can favor an immunotherapeutic treatment, having so great clinical relevancy. However, the pretreatment of the raw extract can potentialize its response as in the cross-reactivity analysis. Therefore, this paper seeks to pre-treat the Suidasia pontifica extract in order to obtain protein fractions by the “salt out” method and then evaluate the presence of cross-reactivity for the Blo t 5 allergen of Blomia tropicalis. Method: Suidasia pontifica extracts were obtained by the protein precipitation with ammonium sulfate in percentages 0-20%, 20-40%, 40-60%, 60-80%, 80-100% (w/v) at 0 °C. Precipitated fractions were evaluated by protein content, characterized by electrophoresis, and applied in Western Blot and ELISA tests, with positives and negatives controls using the recombinant antigen Blo t 5. Results: With salt saturation level of 80% (w/v), it was achievable to efficiently separate proteins in the raw extract of Suidasia pontifica, resulting in a total content of 13.61 mg mL-1. The immunoassay ELISA exposed the existence of cross-reactivity for Blo t 5 allergen, for crude extract, with allergenic potency of 2.797 ng mL-1. This result was also confirmed by stains obtained in the blot in about 15-16 kDa. For fractions obtained between the percentages of 20 to 100% (w/v) of salt saturation and power was below 1.93 ng mL-1, at the border of the established limit of detection. Conclusion: The “salt out” method is efficient at obtaining concentrated fractions of proteins, as observed when applied in Suidasia pontifica, extract, this being susceptible to cross-interactions, suggesting the possibility of this mite to act as an adjunct in immunotherapy on formulations for desensitization of allergic individuals. ORiginAl ReSeARCh