A Rapid On-Site Assay for the Detection of Influenza A by Capillary Convective PCR.

BACKGROUND: Morbidity and mortality from influenza A (Flu A) have increased in recent years. Timely diagnosis and management are critical for disease control. Therefore, the development of a rapid, accurate, and portable analytical method for on-site analysis is imperative.

OBJECTIVES: The aim of this work was to develop a rapid, on-site, automated assay for the detection of Flu A and to evaluate the assay.

METHODS: A handheld instrument (TD-01) based on capillary convective polymerase chain reaction (PCR) was developed for rapid on-site detection of Flu A. Since a previous version of the instrument, an automated motion mechanism has been introduced to TD-01 to achieve RNA automated testing. The primers and probe used for Flu A detection were designed according to the Flu A gene sequence of matrix proteins. Finally, we evaluated the detection spectra, sensitivity, specificity, and diagnostic performance of the assay.

RESULTS: The TD-01 was able to successfully automatically detect Flu A RNA within 30 min. Results for serially diluted viruses indicated that the lower limit of detection for Flu A was 0.1 TCID50 /ml (50% tissue culture infective dose). After evaluating known virus stocks, including 15 strains of Flu A, four strains of Flu B, and two strains of respiratory syncytial virus (RSV), the assay had a favorable detection spectrum and no obvious cross-reactivity. Method verification based on 554 clinical samples indicated that the sensitivity and specificity of TD-01 were 98.30% (231/235) and 98.75% (315/319), respectively.

CONCLUSIONS: The results indicate that Flu A detection by TD-01 is particularly suitable for on-site testing and has the potential for application in point-of-care testing.