Immunoblot analysis of salivary allergens in 10 mosquito species with worldwide distribution and the human IgE responses to these allergens.

BACKGROUND: Most people develop skin reactions to mosquito bites, however, little is known about mosquito salivary allergens and the IgE responses to them.
OBJECTIVES: We sought to identify these allergens and the specific IgE responses they elicit.
METHODS: Saliva or salivary gland extracts were prepared from 10 mosquito species, including seven species with worldwide distribution: Aedes (Ae.) aegypti, Ae. vexans, Ae. albopictus, Ae. togoi, Ae. triseriatus, Culex (Cx.) quinquefasciatus, Cx. pipiens, Cx. tarsalis, Anopheles (An.) sinensis, and Culiseta (Cs.) inornata. Proteins from these preparations were separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis and transferred to nitrocellulose membranes, which were immunoblotted by sequential incubations with human serum, monoclonal anti-human IgE, and enzyme-conjugated goat anti-mouse IgG. Salivary allergens were analyzed by using a pooled serum from subjects allergic to mosquitos. Individual IgE responses to each allergen were evaluated in 12 subjects allergic to mosquitos living in Canada, the United States, and China, as well as in five subjects not allergic to mosquito bites. To study species-shared allergens, the membranes were immunoblotted with two rabbit antibodies specific to recombinant mosquito salivary proteins.
RESULTS: Three to sixteen salivary allergens with molecular masses ranging from 16 to 95 kd were found in each species. Both species-shared and species-specific allergens were identified by molecular masses, binding to the two rabbit antibodies, and individual IgE responses to species indigenous to and absent from the regions where the subjects lived. Salivary allergens, especially from Ae. aegypti, Ae. vexans, and Ae. albopictus, elicited higher IgE responses in subjects allergic to mosquitos than in nonallergic subjects.
CONCLUSIONS: Species-shared and species-specific allergens that cause IgE responses in subjects allergic to mosquitos are immunologically identified. Species-shared allergens are the most important for potential use in diagnosis and immunotherapy.