Quantum dot immunochromatographic strip for rapid and sensitive detection of H5 subtype avian influenza virus

The H5 subtype avian influenza viruses (AIVs) pose a major threat to wild fowl and poultry. Additionally, they can overcome the species barrier, inducing human infection, which may become fatal. Thus, the H5 subtype AIVs remain a global public health burden, with a huge pandemic potential. Therefore, it is imperative to establish a rapid, sensitive, and specific method for detecting H5 subtype AIV infection for diagnostic and preventive purposes. The quantum dot fluorescent microsphere-based immunochromatographic strip (QDFM-ICS) is being widely used for detecting various viruses. We here developed a pair of monoclonal antibodies (2F2 and 2B7) by immunizing mice with the A/duck/Zhejiang/6D2/2013(H5N6) virus and covalently linking them with quantum dots to generate a QDFM-ICS for detecting H5 subtype AIVs. The QDFM-ICS showed a limit of detection of 0.0625 hemagglutination units (HAU) per 80 µL for live H5 subtype AIVs and 1.2 ng/mL purified H5N6 hemagglutination protein, respectively. In addition, it demonstrated good reproducibility with a coefficient of variation of < 10%, showing a high degree of repeatability. The strips exhibited a full percentage of specificity. Notably, their sensitivity and specificity remained unaffected even when stored for 3 months at room temperature or 4 °C. Furthermore, the application in practical testing on field samples demonstrated a strong correlation between QDFM-ICS and real-time PCR. The QDFM-ICS can be used in less time, with a simpler operation, and lesser expenditure. Thus, QDFM-ICS is a practical and promising technique for detecting H5 subtype AIVs, especially in point-of-care testing.