Quantum Dots Labeled Antibody as a Fluorescence Probe for Hantavirus Fluoroimmunoassay

Quantum dots are now widely used for immune detection purposes. We developed a practical and robust quantum dots labeled goat anti-human IgG reagent as a high fluorescent intensity photostable marker for effective antibody detection. The optimum reaction time, pH, and concentration of goat anti-human IgG required for effective labeling was 2 h, 6.0, and 20 mu g/mL, respectively. Combined with an indirect immunofluorescence assay, we developed an immune detection system for Hantavirus (HV) using quantum dots instead of chemical fluorochromes. This immune detection scheme was rapid, specific, and sensitive with a detection range of 5 ng/mL-10 mu g/mL, and no cross-reaction with 20 samples positive for hepatitis B virus (HBV), herpes simplex virus 1, and hepatitis C virus. The optimized response time of the immune detection system for HV and HBV revealed that the antibody-antigen binding reaction equilibrated within 30 min, while the antibody and QDs labeled goat anti-human IgG combination equilibrated in 10 min. The whole immune detection process took around 40 min to complete. PCR was used as the gold standard for comparing the QDs and enzyme linked immunosorbent assay (ELISA) detection methods using 207 clinical serum samples. The sensitivity of QDs immune detection was 96%, its specificity was 98.7%, while the Youden index was 94.7%. The results of the matched chi-square test used to compare the QDs and ELISA immune detection systems revealed no significant difference between the two methods. The QDs-antibody-antigen complex had a long fluorescence lifetime, making it a relatively straightforward process to monitor or review the results. This new method has potential for routine detection of HV infection in humans.