MONOCLONAL-ANTIBODIES FOR THE RAPID DIAGNOSIS OF INFLUENZA-B VIRUS-INFECTIONS BY ELISA - PRODUCTION AND CHARACTERIZATION

Background: Monoclonal antibodies directed against conserved epitopes of viral proteins have substantially improved the accuracy of several immunochemical methods in diagnostic virology. Objectives: To characte rize mouse monoclonal antibodies directed against structural protein a ntigens of influenza-B virus and evaluate their use as diagnostic reag ents for the direct detection of such antigens in clinical specimens f rom patients with respiratory infections of unknown aetiology. Study d esign: (a) Production and characterization of monoclonal antibodies ag ainst influenza-B viral antigens, and (b) their use in two different E LISA systems for detecting influenza-B antigen either directly in clin ical specimens or after confirmation by rapid culture in MDCK cells. R esults: Four monoclonal antibodies were selected for their specificity for the nucleoprotein antigen as demonstrated by Western blot analysi s. The specificity of these antibodies for different epitopes of the n ucleoprotein was demonstrated by competition experiments, using unlabe lled and biotin-labelled purified antibodies in a sandwich assay. All four antibodies belong to the mouse IgG(2a) isotype, lack haemagglutin ation inhibition and neutralization properties and exhibit titres as h igh as 10(-6) in ELISA with as little as 30 ng purified influenza-B vi rus. ELISA methods using these antibodies detected only influenza-B vi ral antigens in direct testing of clinical specimens from patients wit h known influenza-B or influenza-A infections, or after reisolating vi rus from such specimens in tissue culture of MDCK cells. Conclusion: T he antibodies were suitable for the direct detection and typing of inf luenza-B virus in clinical specimens or for use in rapid confirmation cultures.