A time-resolved fluoroimmunoassay for the quantitation of rabies virus nucleoprotein in the rabies vaccine.

Sensitive, precise and rapid detection tests are needed in the quality control of rabies vaccine for rabies virus nucleoprotein. Previous studies for quantitation of rabies virus nucleoprotein focused on enzyme-linked immunosorbent assay (ELISA). A novel immunoassay for rapid determination of rabies virus nucleoprotein in rabies vaccine was first established by time-resolved fluoroimmunoassay (TRFIA). Based on a sandwich-type immunoassay format, analytes in samples were captured by one monoclonal antibody coating in the wells and "sandwiched" by another monoclonal antibody labeled with europium chelates. The immunocomplex was retained after washing, and then adopted treatment with enhancement solution; fluorescence was then measured according to the number of europiumions dissociated. Levels of the rabies virus nucleoprotein were measured in a linear range (5-2500 mEU/mL) with a lower limit of quantitation (0.95 mEU/mL) under optimal conditions. The repeatability, recovery, and linearity of the immunoassay were demonstrated to be acceptable. The correlation coefficient of nucleoprotein values obtained by novel TRFIA method and ELISA method was 0.981. These results showed good correlation and confirmed that this sensitive, precise and rapid TRFIA was feasible and could be more suitable for the quality control in the process of rabies vaccine production than ELISA.