In-house RT-PCR detection of hepatitis A virus in human plasma pools used for the manufacture of medicinal products

Hepatitis A virus (HAV) is the most frequent cause of viral hepatitis worldwide and is transmitted through the fecal-oral route. However, HAV can also be transmitted by blood-derived products. This is due to the fact that viremia occurs during the asymptomatic phase of HAV infection, enabling infected blood or plasma donations to occur. Viral inactivation/removal steps are included during manufacturing of plasmaderived products. However, HAV is a small non-enveloped virus very difficult to remove with traditional viral inactivation procedures. To accomplish European guidelines for pooled human plasma (treated for virus inactivation), plasma manufacturers have been implementing HAV nucleic acid test (NAT) screening on plasma pools. In this study, we validate an in-house multiplex reverse-transcription real-time PCR (RT-PCR) assay targeting HAV RNA and an internal control with hydrolysis probes for amplicon detection. The HAV RNA test was validated by assessing limit of detection, robustness, sensitivity and specificity according to European Pharmacopoeia (Ph. Eur.) guidelines. Our assay is able to detect 100 IU/mL of all human HAV genotypes that have been described so far. The multiplex assay shows remarkable sensitivity with a 95% lower limit of detection of 5.2 IU/mL. Also, our HAV test shows good robustness, precision, and specificity. We conclude that our assay broadly meets the requirements for its purpose. The implementation of this test in the production process of plasma-derived products will increase their safety.

Implementation of NAT Screening for West Nile Virus and Experience with Seasonal Testing in Germany

BACKGROUND

West Nile virus (WNV) can be transmitted by transfusion through infected blood components. In Germany, a 28-day deferral for blood donors of therapeutic blood components who had spent at least 2 days in WNV-endemic areas from June 1 to November 30, 2014 was enforced. Otherwise, screening of blood donors for WNV RNA or the application of pathogen reduction techniques are appropriate alternatives.

METHODS

In the present study, we evaluated NAT screening for the detection of WNV in blood components. A total of 58 minipools consisting of 357 individual blood donors were screened for the presence of WNV RNA employing an automated high-volume extraction method using the RealStar WNV RT-PCR Kit. Additionally, different WNV reference reagents were quantified to prove the status quo of standardization. Four different WNV real-time NAT kits were compared using samples of an external quality assessment panel.

RESULTS

The 95% lower detection limit of the WNV MP-NAT was determined to 30.2 copies/ml (95% CI 24.2-45.4 copies/ml). No WNV RNA-positive minipool was detected. Quantification of WNV reference reagents revealed shortcomings in standardization. Comparison of several WNV NAT assays showed considerable differences in assay sensitivities and particularly a missing detection of WNV lineage 2. Implementation of seasonal WNV MP-NAT screening was demonstrated.

CONCLUSION

Actually, WNV infections in Germany are rare events introduced by returning travelers, but surveillance of these emerging infections is important for safety in blood supply. The validation study pointed out the need for standardization of WNV NAT because of current lack of an international standard for WNV RNA.