Rapid multiserotype detection of human rhinoviruses on optically coated silicon surfaces

Background: More than 100 immunologically distinct serotypes of human rhino viruses (HRV) have been discovered, making detection of surface exposed cap sid antigens impractical. However, the non-structural protein 3C protease ( 3Cpro) is essential for viral replication and is relatively highly conserve d among serotypes. making it a potential tai get for diagnostic testing. Th e thin him biosensor is an assay platform that can be formatted into a sens itive immunoassay for viral proteins in clinical specimens. The technology utilizes an optically coated silicon surface to convert specific molecular binding events into visual color changes by altering the reflective propert ies of light through molecular thin films, Objective: To develop a rapid te st for detection of HRV by developing broadly serotype reactive antibodies to 3Cpro and utilizing them in the thin film biosensor format. Study design : Polyclonal antibodies to 3Cpro were purified and incorporated into the th in film assay. The in vitro sensitivity, specificity and multiserotype cros s-reactivity of the 3Cpro assay were tested. Nasal washes from naturally in fected individuals were also tested to verify that 3Cpro was detectable ill clinical specimens. Results: The 3Cpro assay is: a 28-min, non-instrumente d room temperature test with a visual limit of detection of 12 pM (picomola r) 3Cpro. In terms of viral titer, as few as 1000 TCID50 equivalents of HRV 2 were detectable. The assay detected 45/52 (87%) of the HRV serotypes test ed but showed no cross-reactivity to common respiratory viruses or bacteria . The thin film assay detected 3Cpro ill HRV-infected cell culture supernat ants coincident with first appearance of cytopathic effect. Data are also p resented demonstrating 3Cpro detection from clinical samples collected from HRV-infected individuals. The assay detected 3Cpro in expelled nasal secre tions from a symptomatic individual on the first day of illness. In additio n, 9/11 (82%) concentrated nasal wash specimens from HRV infected children were positive in the 3Cpro lest. Conclusion: We have described a novel, sen sitive thin film biosensor for rapid detection of HRV 3Cpro. This test may be suitable for the point of care setting, where rapid HRV diagnostic test results could contribute to clinical decisions regarding appropriate antibi otic or antiviral therapy. (C) 2001 Elsevier Science B.V. All rights reserv ed.