Programmpunkt

10:30

Titel: Evaluation of a high-throughput PCR system for detection of SARS-Coronavirus-2 RNA in human plasma
ID: VS-3-3
Art: Abstractvortrag
Redezeit: 10 + 5 min
Session:
ARGE Plasmapherese
VS-3

Referent: Philipp Steininger (Erlangen)


Abstract - Text

Offenlegung Interessenkonflikt:

kein Interessenskonflikt

Methods

The dual-target cobas SARS-CoV-2 real-time PCR assay (Roche Diagnostics), licensed for swab samples from the upper respiratory tract, was evaluated for detection of SARS-CoV-2 RNA in plasma using the standard instrument settings and reagents. Test performance was assessed by spiking plasma with SARS-CoV-2 from different positive clinical samples and by performing a comparative evaluation between sample types plasma and swab-media. Sensitivity, specifity, intra- and interassay-variability and linearity were analysed. In total, 124 SARS-CoV-2-RNA positive, negative and possible cross-reactive samples were prepared for the test panel.

Results

Two serial dilutions in plasma of high and low positive clinical samples (characterized by ct values) were performed and showed a good analytical sensitivity. Ct values of target 1 (ORF1/a) compared to target 2 (envelope E-gene) were slightly lower for all samples (mean difference: - 0.64) except for one low positive samples (target 1 negative, target 2: ct 38,13).


Low intra-assay variabilities for positive (mean ct 25.45) and low positive (mean ct 29.93) samples (n = 10) were found and the CVs were 0.72% and 1.10%, respectively. The paired comparison of virus spiked plasma and swab media showed a high degree of correlation (Figure 1). No cross-reactivity was observed for the blood-borne viruses HBV, HCV, HEV and HIV-1.

Background

The highly sensitive detection of SARS-CoV-2 RNA in humane plasma samples is of utmost importance for individual patient management and possibly blood transfusion safety. In infected patients viral RNA was detected in multiple body fluids beyond the respiratory tract including blood. Until now, viremia was mostly detected in patients with severe disease course. However, in Germany there is no commercially available and licenced high-throughput assay for detection of SARS-CoV-2 RNA in blood.

Conclusion

This validation showed the feasibility and performance of the cobas® SARS-CoV-2 PCR assay for the detection of SARS-CoV-2 RNA in human plasma. The diagnostic performance for the sample type human plasma was non-inferior to swab media in virus spiking experiments. Differences between both sample types might be the stability of free viral RNA, as cobas PCR media contains guanidine hydrochloride for inactivation of RNases.