Validation of fluorescence focus assay for virus titer detection in hexavalent rotavirus vaccine

Objective To validate the feasibility of fluorescence focus assay (FFA) as a method of virus titer detection for hexavalent rotavirus vaccine. Methods The titers of rotavirus types G1, G2, G3, G4, G8, G9 were detected by FFA, and the specificity, precision, linearity, accuracy, range and robustness of FAA were validated. Results The different types of rotaviruses had specific fluorescence focus reaction with corresponding monoclonal antibody, and no cross reaction with anti-heterotypic virus antibody. The relative standard deviations of results in inner- and inter-assay were all 0.99. The recovery rates of different concentrations of 6 types viruses were 90%-120%. The FFA detection limits of rotavirus types G1, G2, G3, G4, G8 and G9 titers were >2.8, >4.2, >3.7, >3.6, >4.1 and >4.2 lg fluorescence focus unit/ml, respectively, which met the quality control requirment of hexavalent rotavirus vaccine. Conclusion The FFA has good specificity, precision, linearity and accuracy, and can be applied to detection of virus titers in hexavalent rotavirus vaccine. Key words: Rotavirus vaccines; Fluorescent antibody technique; Methods