Investigating utilising the Alinity m platform to detect hepatitis C virus RNA in dried blood spot samples

Alinity m, a Random-Access System, for Hepatitis B Virus DNA Quantification in Plasma and Whole Blood Collected on Dried Blood Spots

The International Liver Association recommends the use of accurate and sensitive molecular methods for determination of hepatitis B virus (HBV) DNA levels in plasma or serum of chronic HBsAg carriers. The level of HBV replication represents the strongest predictive biomarker associated with disease progression and long-term outcome of chronic HBV infection. The purpose of this study was to evaluate the ability to the new Alinity m System to detect and quantify HBV DNA in plasma and whole blood collected on dried blood spots (DBS). Paired plasma and DBS samples from patients chronically infected with various HBV genotypes were tested in parallel for HBV DNA detection and quantification. There is a linear relationship between HBV DNA levels measured in plasma samples using the Alinity m HBV assay and the Xpert HBV viral load assay, used for comparison. A slight deviation (0.03 ± 0.31 log IU/mL) was observed within the quantitative range. In DBS, HBV DNA levels closely correlated with levels measured in plasma. All patients had detectable and quantifiable HBV DNA by DBS testing, except for one patient with a plasma HBV DNA level above 2,000 IU/mL. In conclusion, the newly developed real-time PCR-based assay Alinity m HBV assay can correctly detect HBV DNA in DBS, especially for patients with blood HBV DNA levels above 2,000 IU/mL, and also accurately quantify HBV DNA in plasma samples.

IMPORTANCE Hepatitis B virus is one of the most prevalent blood-borne viruses affecting the liver and causing acute and chronic hepatitis. Only a small proportion of people with HBV infection are diagnosed. HBV DNA measurement is critical in clinical practice for the diagnosis and treatment decisions of patients requiring antiviral therapy. Dried blood spot (DBS) collection provides a simple, practical, and acceptable alternative to venous blood collection, especially in community settings. We have demonstrated high sensitivity and specificity for HBV DNA detection in DBS compared to plasma samples, especially when using clinically relevant cutoffs of 2,000 and 20,000 IU/mL. Results support the use of DBS in community-based settings.

Real-Life Head-to-Head Comparison of Performance of Two High-Throughput Automated Assays for the Detection of SARS-CoV-2 RNA in Nasopharyngeal Swabs: The Alinity m and cobas 6800 SARS-CoV-2 Assays

The Alinity m (Abbott Molecular, Des Plaines, IL) automated molecular analyzer allows continuous loading of samples and sample-to-result molecular detection of several microorganisms. The detection of SARS-CoV-2 by the Alinity m was compared with that of the cobas 6800 (Roche Molecular Systems, Branchburg, NJ; standard comparator) in a manufacturer-independent clinical evaluation on 2157 consecutive nasopharyngeal swab samples. Valid initial results on Alinity m and cobas 6800 were obtained from 2129 (98.7%) and 2157 (100%) samples, respectively. The overall percent agreement (95% CI) was 98.3% (2092/2129 [97.6%-98.7%]); positive percent agreement, 100% (961/961 [99.6%-100%]); negative percent agreement, 96.8% (1131/1168 [95.7%-97.7%]); and high κ value, 0.965 (0.954-0.976). There were 37 discordant results on Alinity m and, based on discordant analyses, including previous and/or follow-up PCR results, 22 could be considered analytically true positive with high probability. Due to a lack of additional information and an inability to perform repeated/further testing, the status of the remaining 15 discordant results remained unresolved. The throughput of the two analyzers was compared using testing on 564 samples in parallel across two 8-hour shifts in clinical practice. The turnaround times were compared using processing of 94 routine samples in parallel on each working day for 5 consecutive days. The two analyzers showed similar performance, with certain differences that have potential importance in some laboratory settings.