Virus detection using filament‐coupled antibodies

Two attractive features of ELISA are the specificity of antibody–antigen recognition and the sensitivity achieved by enzymatic amplification. This report describes the development of a non‐enzymatic molecular recognition platform adaptable to point‐of‐care clinical settings and field detection of biohazardous materials. This filament‐antibody recognition assay (FARA) is based on circumferential bands of antibody probes coupled to a 120 μm diameter polyester filament. One advantage of this design is that automated processing is achieved by sequential positioning of filament‐coupled probes through a series of 25–60 μL liquid filled microcapillary chambers. This approach was evaluated by testing for the presence of M13KO7 bacterial virus using anti‐M13KO7 IgG 1 monoclonal antibody coupled to a filament. Filament motion first positioned the antibodies within a microcapillary tube containing a solution of M13KO7 virus before moving the probes through subsequent chambers, where the filament‐coupled probes were washed, exposed to a fluorescently labeled anti‐M13K07 antibody, and washed again. Filament fluorescence was then measured using a flatbed microarray scanner. The presence of virus in solution produced a characteristic increase in filament fluorescence only in regions containing coupled antibody probes. Even without the enzymatic amplification of a typical ELISA, the presence of 8.3 × 10 8 virus particles produced a 30‐fold increase in fluorescence over an immobilized negative control antibody. In an ELISA comparison study, the filament‐based approach had a similar lower limit of sensitivity of ∼1.7 × 10 7 virus particles. This platform may prove attractive for point‐of‐care settings, the detection of biohazardous materials, or other applications where sensitive, rapid, and automated molecular recognition is desired. © 2005 Wiley Periodicals, Inc.