Allergens involved in the cross-reactivity of Aedes aegypti with other arthropods.

BACKGROUND: Cross-reactivity between Aedes aegypti and mites, cockroaches, and shrimp has been previously suggested, but the involved molecular components have not been fully described. OBJECTIVE: To evaluate the cross-reactivity between A aegypti and other arthropods. METHODS: Thirty-four serum samples from patients with asthma and/or allergic rhinitis were selected, and specific IgE to A aegypti, Dermatophagoides pteronyssinus, Dermatophagoides farinae, Blomia tropicalis, Periplaneta americana. and Litopenaeus vannamei was measured by enzyme-linked immunosorbent assay. Cross-reactivity was investigated using pooled serum samples from allergic patients, allergenic extracts, and the recombinant tropomyosins (Aed a 10.0201, Der p 10, Blo t 10, Lit v 1, and Per a 7). Four IgE reactive bands were further characterized by matrix-assisted laser desorption/ionization tandem time of flight. RESULTS: Frequency of positive IgE reactivity was 82.35% to at least one mite species, 64.7% to A aegypti, 29.4% to P americana, and 23.5% to L vannamei. The highest IgE cross-reactivity was seen between A aegypti and D pteronyssinus (96.6%) followed by L vannamei (95.4%), B tropicalis (84.4%), and P americana (75.4%). Recombinant tropomyosins from mites, cockroach, or shrimp inhibited the IgE reactivity to the mosquito at a lower extent than the extracts from these arthropods. Several bands of A aegypti cross-reacted with arthropod extracts, and 4 of them were identified as odorant binding protein, mitochondrial cytochrome C, peptidyl-prolyl cis-trans isomerase, and protein with hypothetical magnesium ion binding function. CONCLUSION: We identified 4 novel cross-reactive allergens in A aegypti allergenic extract. These molecules could influence the manifestation of allergy to environmental allergens in the tropics.

Identification and Characterization of IgE-Binding Tropomyosins in Aedes aegypti.

BACKGROUND: The mosquito Aedes aegypti is a potential source of important clinically relevant allergens. However, the allergenicity and cross-reactivity of most of these has not been fully described. METHODS: Natural wild-type mosquito tropomyosin was purified by size exclusion and anionic-exchange chromatography from an A. aegypti extract. Further characterization was accomplished by MALDI-TOF/TOF. Two recombinant variants of tropomyosin were obtained by expression in Escherichia coli. Specific IgE measurement by ELISA and skin tests for mosquito extract were performed in 12 patients with asthma or allergy rhinitis residing on the Caribbean island of Martinique. Cross-reactivity between natural A. aegypti tropomyosin and recombinant tropomyosins from A. aegypti, house dust mite, shrimp and Ascaris lumbricoides was analyzed by ELISA competition. RESULTS: Four variants of natural tropomyosin were purified. A band of 32 kDa in SDS-PAGE representing 2 tropomyosin variants (Aed a 10.0101 and Aed a 10.0201) reacted with specific IgE of 4 of the 12 (33%) allergic patients and with rabbit polyclonal anti-shrimp tropomyosin. A high degree of cross-reactivity (60-70%) was detected between natural mosquito tropomyosin and Blo t 10, Der p 10 and Lit v 1, and a lower degree with Asc l 3 from A. lumbricoides (<30%). rAed a 10.0101 inhibited IgE binding to natural A. aegypti tropomyosin; however, rAed a 10.0201 showed a low inhibitory capacity. CONCLUSION: Tropomyosin is a new IgE-binding protein from A. aegypti. Two of the 4 variants identified showed different degree of cross-reactivity with tropomyosins from other arthropods. The potential allergenic role of each variant should be further investigated.

Impact of quality control matrix effect: application to the calculation of uncertainty of measurement in one-stage clotting factor VIII assay.

In Europe, the ISO 15 189 standard requires uncertainty of measurement to be calculated for all measurands. We calculated the analytical imprecision and bias of our factor VIII coagulometric assay method between 5 and 80 U/dl, using plasmas expected to be at 5, 30 and 80 U/dl of factor VIII. We implemented Meijer et al.'s [Clin Chem 2002; 48:1011-1015] long-term coefficient of variance, bias and also uncertainty of measurement calculations. Assessments used reference plasma diluted in severe haemophilic plasma, in immunodepleted factor VIII-deficient plasma and in bovine serum albumin. With plasmas diluted in severe haemophilic and immunodepleted factor VIII-deficient plasma, calculated uncertainty of measurement was 10% compared with 15% (i.e., 50% greater) for plasma diluted in albumin buffer or as calculated from European Concerted Action on Thrombosis consensus values. It is thus important to approximate the patient sample matrix to obtain as precise an estimation as possible of assay method uncertainty of measurement.