ESTABLISHMENT OF THE FIRST NATIONAL STANDARD FOR NUCLEIC ACID AMPLIFICATION TECHNOLOGY ASSAY FOR HCV RNA

Abstract

The First WHO International Standard for HCV RNA for Nucleic Acid Amplification Technology (NAT) Assay (96/790) was established in 1997. The aim of our collaborative study was the establishment of the Japanese National Standard for HCV RNA calibrated against the WHO International Standard. The candidate materials were evaluated in the following two steps. First, titers of two HCV positive plasma (119 and 122) diluted in cryosupernatant were evaluated, and plasma 122 was chosen as the source plasma for the candidate for the national standard. Then, candidate 122 was prepared by diluting the source plasma to approximately 10⁵ international units (IU)/ml in cryosupernatant. The relative potency of the candidate was measured against the International Standard by the end-point method. Seven laboratories from three countries participated in the collaborative study. Four laboratories used the Roche Amplicor assay (Version 1) and 3 laboratories used in-house PCR methods. There was reasonable agreement among the mean estimates from the laboratories. The overall mean potency of the candidate relative to the International Standard was 10^5.00 (10^4.80-10^5.20) IU/ml. The sample was accepted as the first Japanese national standard and assigned a titer of 100, 000IU/ml. Each vial of the National Standard contains 0.5ml of HCV plasma (genotype 1b) diluted in cryosupernatant and should be stored at-80°C.