Establishment of Eu3+ / Sm3+ dual?label time?resolved fluoroimmunoassay for measurement of anti?bodies to hepatitis C virus and its clinical application / 中华核医学与分子影像杂志

ABSTRACT

Objective To establish a time-resolved fluoroimmunoassay (TRFIA) system for simul-taneous measurement of immunoglobulin (Ig)M and IgG antibodies to HCV. Methods Recombinant HCV antigen was fixed on microtiter plates to detect serum HCV antibodies. Eu3+-labeled anti-human IgM and Sm3+-labeled anti-human IgG were prepared. HCV-IgM and HCV-IgG TRFIA were established using indirect assay and further optimized and evaluated. The one-sided 95th-percentile was used to calculate the cut-off (CO) values. Results Defining 1 sample/ CO (S/ CO) as measuring unit, the detection limit was 0.06 S/ CO for HCV-IgM and 0.15 S/ CO for HCV-IgG. When diluted a strong-positive specimen from 1 :12.5 to 1 :51200, there was a good liner range within 1 :12.5 to 1 :12800 for HCV-IgM and 1 :25 to 1 :6400 for HCV-IgG. The average intra-assay CV of HCV-IgM and HCV-IgG were 3.37％ and 3.66％, respectively, and the aver-age inter-assay CV were 6.52％ and 6.75％, respectively. Compared with enzyme-linked immunosorbent as-say (ELISA) kits, the positive conformity rate, the negative conformity rate and total conformity rate were 100.0％(20/ 20), 90.0％(18/ 20), 95.0％(38/ 40) for HCV-IgM TRFIA, and were 100.0％ (20/ 20), 95. 0％(19/ 20), 97.5％(39/ 40) for HCV-IgG TRFIA, respectively. Additionally, the established HCV-IgM and HCV-IgG assay kits presented good stability with a decline in the value of fluorescence of 11.1％and 9.5％ respectively after being stored at 37 ℃ for 7 d. Conclusions The established HCV-IgM and HCV-IgG TRFIA could simultaneously measure HCV-IgM and HCV-IgG antibodies at one step. The method has wider detectable range and may be a more sensitive, stable, and reliable method for diagnosing HCV in-fection.