Performance of Roche qualitative HEV assay on the cobas 6800 platform for quantitative measurement of HEV RNA.

Abstract

Hepatitis E virus (HEV) infection is an increasingly recognized cause of acute and chronic hepatitis in high-income countries and is the most frequent cause of acute viral hepatitis in many European countries. Appropriate tools to detect and quantify HEV RNA are needed. This study aimed to evaluate the performance of the Roche cobas® HEV assay and compare it with the Fast Track Diagnostics (FTD) Hepatitis E RNA assay. HEV viral load determination and lower limit of detection (LOD, defined as the lowest amount of viral copies that could be detected in 95 % of repeats) were assessed using a WHO standard dilution panel, testing 240 samples of various concentrations. Reproducibility was tested at three different concentration levels, for different genotypes, and with different sample types (serum, plasma) in 30 samples. Sample stability was analyzed after three freeze/thaw cycles in 25 samples. Cobas HEV assay showed a strong linear relationship between log of HEV WHO dilution series and Ct values over the reportable range from 200-5000 IU/mL HEV RNA copies. The amplification efficiency was higher than 92 %. LOD was 22 IU/mL (95 % CI: 17.4-31.8) and reproducibility tests showed a 100 % nucleic acid test (NAT) reactivity of cobas HEV for WHO dilution series (range 200-5000 IU/mL, n = 90). Cobas HEV assay detected all different HEV genotypes from biobank samples irrespective of the sample type. NAT reactivity of cobas HEV was not affected by three freeze/thaw cycles. Roche cobas HEV assay is a powerful NAT tool in terms of robustness, reproducibility and linearity. It is a feasible alternative for high-volume testing.