RAPID IMMUNOFILTRATION ASSAY OF NEWCASTLE-DISEASE VIRUS USING A SILICON SENSOR

A rapid nonradioactive sandwich immunoassay which utilizes biotin-stre ptavidin mediated filtration capture of immune complexes in conjunctio n with a silicon sensor was developed for the detection of virus. Usin g purified Newcastle disease virus as a model, the lower limits of det ection (LOD) were determined for a number of immunoassay configuration s employing both monoclonal and polyclonal antibodies. The LODs ranged from 1.3 ng/ml (sample volume of 100 mu l) for an incubation of 60 mi n to 400 ng/ml for a 1 min incubation. The sandwich immune complexes w ere formed from one-step incubation of antibody and antigen. No 'hook' effects were observed over a wide range of analyte concentrations. Th e assays were easy to perform and required a total time equal to the i ncubation period plus about 5 min. The assay format is suitable for vi rus, bacteria and protein antigens. New assays can be developed and op timized readily, often within 1 day.