Novel salivary gland allergens from tropical mosquito species and IgE reactivity in allergic patients

World Allergy Organ J. 2020 Feb 17;13(2):100099. doi: 10.1016/j.waojou.2020.100099. eCollection 2020 Feb.

Abstract

Background: Mosquito allergy is common in tropical countries but remains under-diagnosed. This may be due to the lack of knowledge and diagnostic tools for tropical mosquito allergens.

Objective: We aimed to characterize allergens from tropical mosquito species and investigate IgE reactivity in mosquito-allergic patients to the salivary gland proteins from these mosquitoes.

Methods: Salivary gland extract (SGE) from 4 mosquito species, highly distributed in the tropics, including Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles dirus b, were studied. SGE-specific IgE and IgG ELISA were developed, and serum from 64 mosquito-allergic and 22 non-allergic healthy control subjects was assayed. Further investigations using IgE-immunoblots followed by mass spectrometry analysis were performed to identify and characterize allergens from each species.

Results: Mosquito-allergic subjects have detectable serum IgE to SGE derived from local mosquito species, while the IgE levels to Aedes communis using commercially available ELISA were mostly minimal. IgE-immunoblot analysis and mass spectrometry identified 5 novel mosquito allergens from A. albopictus (Aed al 2, Aed al 3), C. quinquefasciatus (Cul q 2.01, Cul q 3), and A. dirus b (Ano d 2). Interestingly, 4 of the 5 new allergens belong to the D7 protein family.

Conclusions & clinical relevance: Five novel allergens from 3 tropical mosquito species were characterized. The majority of mosquito-allergic subjects who live in the tropics have IgE reactivity to these allergens. Our study paves the way for the development of diagnostic tests, component-resolved diagnostics, and future immunotherapy for mosquito allergy in tropical countries.

Keywords: Allergens; IgE; Insect allergy; Mosquito; Tropical species.