Humoral immune responses in mice to a mosquito salivary gland antigen as a target for a diagnostic and immunotherapeutic agent

Abstract

The mouthparts of mosquito are modified to pierce the tissues and suck blood from humans or other mammals. Their bites can cause immediate cutaneous reactions, such as wheal and flare, delayed reactions and occasionally systemic reactions in humans. IgE-mediated allergic reactions caused by mosquito bites are a common problem all over the world. This study was undertaken to determine IgE levels in anti-mouse serum, to elucidate mouse IgE binding patterns and to investigate the immunogenicity of salivary gland antigens of Aedes togoi. Mosquito larvae of Aedes togoi were collected and maintained in the laboratory. The mosquito specific mouse IgE level was measured using ELISA. Polypeptide patterns were analyzed by SDS-PAGE. Western blot was performed with sensitized immune mouse sera, and elucidated mouse IgE binding patterns to salivary gland extracts. Protein band patterns of the salivary gland extracts (SGE) and whole body extracts (WBE) of the specimens were different from one another. Specific mouse IgE reacted to the protein in SGE of 18.0, 33.0, 35.0, 37.0, 45.0, 57.5, 72.0, 90.0 and 150.0 kDa from Aedes togoi. Molecular biological techniques were used to study the genetic information and functions of genes. The cDNA sequencing was carried out to elucidate and compare the genome of Aedes togoi with other coded gene of the allergen. Two previously unknown protein coding genes(DUF 1398, DUF 2528) were identified among the 45 positive clones prepared from the mosquito salivary gland by immunoscreening. Analysis of the 3D structure of DUF1398 and DUF2528 was not similar with any other allergens identified in plants or animals, despite low sequence identities to their templates, the global folds of the 3D models of the cockroach allergen Bla g 4 and the mosquito salivary protein antigen Aed a 2 had a sizable fraction of structural overlap, suggesting that it would be a potential target for therapeutic agents in specific mosquitoes bite allergens.