Development of latex turbidimetric immunoassay for rapid and sensitive detection of influenza virus.

For the rapid and sensitive detection of influenza A and B viruses, a latex turbidimetric immunoassay (LTIA) was developed using latex reagents prepared by the sensitization of anti-influenza A or B monoclonal antibodies on latex particles. We measured the immunoreactivity of these latex reagents to influenza A and B viral antigens. The sensitivity and specificity of LTIA and reverse transcription-polymerase chain reaction (RT-PCR) for the detection of these viruses in clinical specimens (96 nasal swabs) were compared. The absorbance change in the latex agglutination reaction increased for each latex reagent with increasing concentration of the viral antigens. Reaction curves were obtained with each concentration of viral antigens for 5 min. The effective concentration ranges were 0-10 microg/ml for influenza A and 0-20 microg/ml for influenza B. The LTIA using clinical specimens revealed 8 positive and 73 negative results for influenza A and 15 positive and 52 negative results for influenza B. The sensitivities and specificities were 89% (8/9) and 84% (73/87), respectively, for influenza A and 100% (15/15) and 64% (52/81), respectively, for influenza B. The corresponding positive predictive values (PPV) were 36% (8/22) for influenza A and 34% (15/44) for influenza B. The negative predictive values (NPV) were approximately 99% (73/74) for influenza A and 100% (52/52) for influenza B. The LTIA is a rapid and sensitive method for detection of the influenza virus; It can be used for high throughput assay by automatic measurement and can potentially be used during influenza pandemics.