5/6 November 2024
Hepatitis C virus (HCV) infections are a major public health problem in Europe and worldwide. HCV is an enveloped positive-strand RNA virus that is mainly transmitted parenterally through the exchange of infected syringes between drug users or through blood in countries where safe medical practices are not always used.
In Europe, nucleic acid amplification techniques (NAT) have been available for many years to screen for viral contamination in blood derivatives and are currently widely used as routine assays in the blood products industry. NAT assays are highly sensitive and allow early detection of infections in time windows when antibody levels in the plasma of contaminated individuals are undetectable. In this way, they help to increase the safety of blood transfusions and reduce the spread of viral contamination among transfusion recipients. The monographs Human Plasma for Fractionation (0853) and Human Plasma (Treated for Viral Inactivation) (1646) of the European Pharmacopoeia (Ph. Eur.) require that plasma pools be tested for HCV RNA using validated NAT. For this purpose, HCV RNA was introduced as a positive control for NAT tests of BRP batch 1 in 1999.
Now stocks of this reference preparation are almost exhausted, so the European Directorate for the Quality of Medicines &HealthCare (EDQM), under the control of the Biological Standardisation Programme (BSP), initiated a project, code BSP158, to produce a replacement BRP batch 2. The Biological Reference Preparation (BRP) is used by manufacturers and official drug control laboratories as a working standard for routine testing of plasma pools. Fifteen laboratories from Europe and beyond participated in the joint study to calibrate the replacement batch. In this study, different NAT-based assays were used to evaluate the suitability of the candidate material as a replacement for the current BRP (batch 1). The candidate was prepared from a window-period HCV RNA-positive plasma donation and diluted in defibrinated normal plasma. Prequalification testing showed that the batch was homogeneous in terms of fill weight and potency, and that the residual moisture and oxygen levels were suitable for long-term storage. The study demonstrated that the BRP was fit for its intended purpose, i.e. after dilution it could be used as a positive control according to the specifications of the relevant Ph.Eur. monographs.
Final stability studies on accelerated degradation have shown that the material has satisfactory stability at the intended long-term storage temperature, i.e. - 20 °C. However, the BRP will be monitored at regular intervals throughout its lifetime.
Batch 2 is distributed as soon as batch 1 is used up. Details of use will be provided in a companion booklet, which will be made available for free download from the EDQM website in due course. Until then, further information can be found in the full EDQM article and in the published paper "Establishment of Ph.Eur. Hepatitis C Virus RNA for NAT testing BRP batch 2".