WHO/BS/2015.2262 Collaborative Study to Evaluate the Proposed 5th WHO IS for Hepatitis C Virus (HCV) RNA for Nucleic Acid Amplification Technique (NAT)-Based Assays

Overview

The previous 4th HCV IS for NAT (NIBSC code 06/102) was established in 2011, however it was recognised that the material must be shipped on dry ice in order to prevent loss of titre during an ambient shipping process.

A small pilot study was conducted at NIBSC to determine the possible effect that the presence or absence of HCV antibodies may have on the stability of a lyophilised preparation. Following the assessment of six lyophilised formulations containing lyoprotectants and stabilizing buffers in the presence and absence of antibodies to HCV, by six laboratories using different commercial assays, no differences were observed. It was subsequently agreed at the 3 rd joint meeting of the Blood Virology and Clinical Diagnostics Standardisation of Genomic Amplification Techniques meeting held on 30/31st May 2014 in Graz, Austria that a candidate standard for the 5th HCV IS NAT would comprise an antibody negative preparation of genotype 1a.

The candidate 5th HCV IS for NAT (NIBSC code 14/150) was filled and freeze dried at NIBSC in November 2014, 1980 vials were lyophilised with a reconstitution volume of 1.1mL to allow for single vial use on analysers requiring a 1mL input volume. The subsequent international collaborative study was performed from December 2014 to March 2015. 17 laboratories from 11 countries participated in the evaluation of 6 samples including the lyophilised candidate standard and the corresponding frozen liquid bulk. HCV antibody positive plasma and a low titre material intended for use as a secondary reference material were also assessed. Assays comprised mainly of commercial real time PCR methods reporting in both quantitative and qualitative values. The current 4th HCV IS and the previous 2nd IS were both included giving the option of deriving potency comparative to the 2nd standard.

Overall, the results of this study indicate the suitability of the candidate to be established as the replacement 5th WHO International Standard for HCV (NIBSC code 14/150) with an assigned potency of 5.0 log10 IU/vial when reconstituted in 1.1mL of nuclease-free water.