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Background: The house dust mite Suidasia pontifica (Sp) is an important source of allergens in tropical regions that trigger IgE-mediated allergic reactions such as allergic asthma, atopic dermatitis and allergic rhinitis. Detection of Sp-specific proteins are important in the management and prevention of allergic diseases. Objective: The study aimed to provide a proof of concept for a gold nanoparticle-labeled sandwich format Lateral Flow Immunoassay (LFIA) kit for the detection of Sp-specific proteins. Methods: Protein A chromatography-purified rabbit anti-Sp polyclonal antibodies were labeled with gold nanoparticles (AuNP) synthesized from chloroauric acid using the citrate reduction method, then dispensed on a glass fiber pad. Unlabeled antibodies and anti-rabbit IgG were immobilized onto nitrocellulose membrane as test line and control line respectively. Cellulose fiber pad, glass fiber, and the nitrocellulose membrane pad were then assembled as LFIA kit. Results: Protein-A affinity chromatography purification with pre-concentration yielded 1.45 mg/mL of anti-Sp polyclonal antibodies. Synthesized AuNPs with ~20 nm sizes observed under transmission electron microscope were used for antibody conjugation at an optimal pH of 8.5 (borate buffer) and an optimal ratio of 10 μ L 50μg/mL antibody:100 μ L AuNP. Optimal color intensity and fastest migration time were observed with the treatment of 0.05% Tween20 and 10% sucrose in the conjugate pads; 5% BSA and 0.05% Tween20 in the sample pads, and 1% BSA in the test pads. The limit of detection of the LFIA Sp-specific proteins is 0.076 μg/mL. The sensitivity of the Sp LFIA kit is 83% while the specificity is 100%. Conclusion: This is the first report of a prototype for a cost-effective, rapid, and equipment-free detection of the house dust mite Suidasia pontifica.

Domestic arthropods are chief sources of potent allergens that trigger sensitization and stimulate IgE-mediated allergies. Diagnosis and immunotherapy of arthropod allergies rely on the use of natural allergen extracts which are associated with low specificity and efficacy, the risk of anaphylactic reactions, and the extended period of treatment. Most of the problems associated with natural allergen extracts for allergy diagnosis and immunotherapy can be circumvented with the use of recombinant allergens and peptides. Recombinant allergens are recently developed for microarray-based multiallergen tests which provide component-resolved diagnosis (CRD) of the patients sensitization profile. Moreover, recombinant protein technology and peptide chemistry have been used to construct isoallergens, allergen mutants, allergoids, T and B cell peptides, hypoallergens, and mimotopes with reduced allergenicity but enhanced immunogenicity for allergenspecific immunotherapy (SIT) and vaccination. The basics of recombinant arthropod allergen technology are in place providing a lucid future for the advancement of diagnosis and immunotherapy of arthropod allergies.