World Health Organization collaborative study to calibrate the 3rd International Standard for Hepatitis C virus RNA nucleic acid amplification technology (NAT)-based assays.

摘要

BACKGROUND AND OBJECTIVES: A collaborative study was undertaken to evaluate a replacement World Health Organization International Standard for hepatitis C virus (HCV) RNA for nucleic acid amplification technology (NAT)-based assays. The candidate preparations were calibrated in International Units (IUs). MATERIALS AND METHODS: Three new candidate preparations were produced from a single bulk containing anti-HCV-negative, genotype 1a HCV RNA-positive plasma. Two samples were lyophilized (coded Sample 2 and Sample 3), whilst a third (Sample 4) contained liquid/frozen material. The samples were distributed together with the 2(nd) International Standard (Sample 1, NIBSC code 96/798) for evaluation by thirty-three laboratories, from fourteen countries. The panel of samples were assayed on four separate occasions. Stability studies were performed for the lyophilized samples by accelerated thermal degradation. RESULTS: Participants returned data from a wide range of commercial and in-house quantitative and qualitative assays. Twenty-five data sets were returned for quantitative assays and fourteen for qualitative assays. Excellent agreement was observed between laboratories and assay methods. The mean relative potencies of Samples 2-4 were 5.19, 5.41 and 5.70 log(10) IU/ml, respectively, when compared against the 2(nd) International Standard. Samples 2 and 3 demonstrated stability of a similar order to the previous standards. CONCLUSIONS: Based upon the results of the collaborative study, Sample 2 (code number 06/100) was established as the 3rd International Standard for HCV RNA with an assigned unitage of 5.19 log(10) IU/ml. Each vial contains the equivalent of 0.5 ml of material; each vial contains 4.89 log(10) IU of HCV RNA.