Detection of Aeromonas hydrophila by Eu / Lu co-luminescence time-resolved fluoroimmunoassay

Co-luminescence time-resolved fluoroimmunoassay ( TRFIA ) for Aeromonas hydrophila was established. First, A. hydrophila strain B11 was coated in microtitration wells. Then, Eu3 +-labeled bacteria-specific IgG was added in the wells to produce affinity reaction. Finally, time-resolved fluorescence ( TRF) of Eu3 + was measured in enhancement solution containing Lu3 + to reflect the quantity of the strain B11. Because of co-luminescence of Eu3 + and Lu3 + complex, TRF was greatly increased, resulting in improvement of the sensitivity. The conditions of co-luminescence system were optimized. The limit of detection was 1. 0 × 103 cfu / mL, and the linear range was 1. 0 × 103-1. 0 × 106 cfu / mL with the correlation coefficients of 0. 994. The strain B11 was positive in co-luminescence TRFIA, while 12 other contrast strains were negative in the assay. The intra-assay and inter-assay relative standard deviations were 2. 9% and 3. 0%, respectively. The method was used to analyze the tissues including liver, kidney, intestine, gill and muscle from Anguilla janponica infected artificially with the strain B11. The results showed 100% of 35 samples were positive. The positive rate was higher than that of direct TRFIA and ELISA. The established co-luminescence TRFIA has potential application for screening A. hydrophila in aquaculture. © 2021, Youke Publishing Co.,Ltd. All rights reserved.