Architect anti hbs

Testing for antibodies to HBV surface antigen (anti-HBs) and antibodies to HBV core antigen (anti-HBc) was performed using CMIA (ARCHITECT anti-HBs and ARCHITECT anti-HBc, Abbott Diagnostic Division, Wiesbaden, Germany). Samples giving borderline test results were retested. HBV surface antigen (HBsAg) was tested using CMIA (ARCHITECT HBsAg Abbott Diagnostic Division, Wiesbaden, Germany) and confirmed by neutralization test (AxSYM, Abbott Diagnostic Division, Wiesbaden, Germany). Samples were deemed HBsAg⁺ when positive at the neutralization test. Study subjects without available information on all three HBV markers (one case and seven controls) were excluded from analyses on HBV markers.

At the CML, all samples were re-analyzed by CMIA for HBsAg using ARCHITECT HBsAg (Abbott Laboratories, IL,USA) on ARCHITECT i4000SR platform according to the instructions of the manufacturer.
The samples were also analyzed with CMIA for anti-HBs and total anti-HBc using ARCHITECT anti-HBs and ARCHITECT anti-HBc II (Abbott Laboratories, IL, USA), respectively on the ARTCHITECT i4000SR machine following the manufacturer’s instructions. HBsAg positive samples were further analyzed for HBeAg and anti-HBe with the ARCHITECT HBeAg and ARCHITECT anti-HBe (Abbott Laboratories, IL, USA) assays. All HBsAg positive and isolated anti-HBc-positive samples were analyzed for antibodies against hepatitis delta virus (anti-HDV) with the ETI-AB-DELTA K-2 kits (Diasorin, Saluggia, Italy) according to the instructions by the manufacturer.

ARCHITECT anti-HBs (Abbott Ireland Diagnostics Division, Sligo, Ireland) was used as a standard assay, which is a chemiluminescent microparticle immunoassay (CMIA), for the quantitative determination of anti-HBs in human serum and plasma.

Fasting blood was collected from all study participants during months with low sunlight exposure to prevent 25(OH)D concentration from being affected by solar radiation.
Total serum concentration of 25(OH)D [(25(OH)D2 and 25(OH)D3)] was determined using an automatic method based on chemiluminescent immunoassay LIAISON^® 25 OH Vitamin D Total (DiaSorin, Saluggia, Italy) controlled and certified by the Vitamin D Standardization and Certification Program (VDSCP) with the coefficient of variation ≤ 4.0 ng/mL. Vitamin D deficiency was confirmed at < 20 ng/mL, suboptimal concentration at 20–30 ng/mL, optimal concentration at 30–50 ng/mL and high concentration at 50–100 ng/mL [20 (link)].
Anti-HBs titer was determined by the chemiluminescent immunoassay ARCHITECT Anti-HBs (Abbott Laboratories, Sligo, Ireland) with the range of quantitation 0–1000 reported as milli-international units per milliliter (mIU/mL) according to the World Health Organization (WHO) international reference standard [21 (link)]. Three groups of subjects were identified, i.e. ‘negative’, with low anti-HBs titer < 10 mIU/mL, ‘low-positive’ with high anti-HBs titer 10–100 mIU/mL, and ‘positive’ with very high anti-HBs titer > 100 mIU/mL.