A rapid influenza diagnostic test based on detection of viral neuraminidase activity

• Published in: Scientific reports 2022-01, Vol.12 (1), p.505-505, Article 505
• Main Authors: Lin, Xuexiang, Liu, Xiao-Yu, Zhang, Bo, Qin, Ai-Qing, Hui, Kwok-Min, Shi, Kevin, Liu, Yang, Gabriel, Don, Li, X. James
• Format: Article
• Language: English
• Subjects: 631/45/881; 631/61/32; 692/699/255/1578; Antigens; Confidence intervals; Diagnosis; Diagnostic tests; Diagnostic Tests, Routine - instrumentation; Diagnostic Tests, Routine - methods; Enzymatic activity; Enzymes; Exo-a-sialidase; Humanities and Social Sciences; Humans; Immunoglobulin M; Influenza; Influenza A Virus, H7N9 Subtype - enzymology; Influenza A Virus, H7N9 Subtype - genetics; Influenza A Virus, H7N9 Subtype - isolation & purification; Influenza, Human - diagnosis; Influenza, Human - virology; Luciferin; multidisciplinary; Neuraminidase - analysis; Neuraminidase - genetics; Neuraminidase - metabolism; Nucleic acids; Pharynx - virology; Polymerase chain reaction; Reagent Kits, Diagnostic; Reagents; Science; Science (multidisciplinary); Sensitivity analysis; Sensitivity and Specificity; Viral infections; Viral Proteins - analysis; Viral Proteins - genetics; Viral Proteins - metabolism
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-04538-4

Current methods used for diagnosis of acute infection of pathogens rely on detection of nucleic acids, antigens, or certain classes of antibodies such as IgM. Here we report a virus enzyme assay as an alternative to these methods for detection of acute viral infection. In this method, we used a luciferin derivative as the substrate for detection of the enzyme activity of influenza viral neuraminidase as a means for diagnosis of influenza. The resulting commercial test, the qFLU Dx Test, uses a different supply chain that does not compete with those for the current tests. The assay reagents were formulated as a master mix that accommodated both the neuraminidase and luciferase reactions, thereby enabling rapid and prolonged production of stable light signal in the presence of influenza virus in the sample. The assay was evaluated using depository throat swab specimens. As expected, the assay exhibited similar detection rates for all influenza types and subtypes except for A(H7N9), which exhibited lower detection rate due to lower viral titer in the specimens. When throat swab specimens were diluted with the sample buffer of the test kit and tested with the qFLU Dx Test. The sensitivity and specificity were 82.41% (95% confidence interval: 79.66–85.84%) and 95.39% (95% confidence interval: 94.32–96.46%), respectively, for these diluted specimens in comparison to a real-time polymerase chain reaction assay. The uniqueness of the qFLU Dx Test as an enzymatic assay makes it highly complementary with currently available methods.