Analytical comparison of hepatitis B core total antibody serological immunoassays on Atellica and Cobas analyzers using reliable long-term frozen archived samples.

BACKGROUND: Serological detection of total antibodies (IgM and IgG) against hepatitis B core antigen (HBc) is essential for diagnosing and assessing infection status of Hepatitis B virus (HBV). Despite multiple commercialized anti‑HBc total automated assays, comparative assay performance remains limited. METHODS: A subset of long-term frozen serum aliquots (n = 1021) from a previously reported clinical population representative of adults at risk or symptomatic for HBV infection was re-tested using the HBcT2 Atellica IM assay designed without the need for a retest zone. HBcT2 Index values obtained in 2020 and 2025 were compared by regression analysis and qualitative reactive/nonreactive interpretation agreement. The subset was also tested using the Roche Elecsys anti-HBcII assay on Cobas analyzer, and positive/negative percent agreements (PPA/NPA) were calculated to assess the methods agreement. RESULTS: Strong linear relationships (slope, 0.98; Pearson's r, 0.993), and PPA/NPA > 99.5% between 2020 and 2025 HBcT2 Index values showed excellent agreement confirming the reliability of the archived clinical samples. Qualitative agreement (PPA/NPA) between the Atellica IM HBcT2 and Roche Elecsys anti-HBcII was high in the population overall (PPA/NPA's >96%) and among HBV categories (PPA/NPA's >90%). CONCLUSION: The Atellica IM HBcT2 assay on the Atellica IM analyzer demonstrated high qualitative agreement with an established comparator assay for detecting total anti-HBc antibodies, thus expanding the range of valuable diagnostic methods available for HBV laboratory testing. The results were comparable to the Roche Elecsys anti-HBcII assay in a high-risk/symptomatic population.