Background
Allergic reactions to mosquito bites are an increasing clinical concern. Due to the lack of availability of mosquito salivary allergens, they are underdiagnosed. Here, we reported a newly cloned mosquito Aedes (Ae.) aegypti salivary allergen.
Methods
A cDNA encoding a 30‐kDa Ae. aegypti salivary protein, designated Aed a 3, was isolated from an expression library. The full‐length cDNA was cloned into a baculovirus expression vector, and recombinant Aed a 3 (rAed a 3) was expressed, purified, and characterized. Skin prick tests with purified rAed a 3 and Ae. aegypti bite tests were performed in 43 volunteers. Serum rAed a 3‐specific IgE levels were measured in 28 volunteers.
Results
The primary nucleotide sequence, deduced amino acid sequence, and IgE‐binding sites of Aed a 3 were identified. rAed a 3‐selected antibodies recognized a 30‐kDa Ae. aegypti saliva protein. rAed a 3 bound IgE in mosquito‐allergic volunteers and the binding could be inhibited by the addition of natural mosquito extract dose dependently. Immediate skin test reactions to rAed a 3 correlated significantly with mosquito bite‐induced reactions. Of the bite test‐positive volunteers, 32% had a positive rAed a 3 skin test and 46% had specific IgE. No bite test‐negative volunteers reacted to rAed a 3 in either the skin tests or the IgE assays, confirming the specificity of the assay.
Conclusions
Aed a 3 that corresponds to the Aegyptin protein is a major mosquito salivary allergen. Its recombinant form has biological activity and is suitable for use in skin tests and specific IgE assays in mosquito‐allergic individuals.