Antigen detection immunoassay using dipsticks and colloidal dyes.

A dipstick colloidal dye immunoassay (DIA) for multiple antigen detection is described. The test combines the concepts of double antibody (Ab) sandwich ELISA, dot blotting, and colloidal particle-linked Abs to produce a dipstick test for multiple antigen (Ag) detection. Dipsticks prepared from Ab coated nitrocellulose membrane mounted on acetate strips served as the assay capture matrix. Abs absorbed to colored dye particles from a family of commercially available textile dyes (Dye/Ab reagent) served as Ag detecting reagents. DIA and enzyme labelled dot blot assays showed similar Ag detection limits down to a sensitivity of 10 ng/ml. In a pilot study, an assay designed to detect species-specific IgG for use in mosquito bloodmeal identification demonstrated the feasibility of the technique. Experiments comparing bloodmeal analysis of mosquitoes using DIA and ELISA methods showed 100% agreement. This DIA method provides an inexpensive, simple, robust test for multiple Ag detection without instrumentation suitable for a wide variety of field applications.