Hepatitis B virus serological and virological activities in blood donors with occult hepatitis B

Abstract

Introduction: We have previously determined that the prevalence of occult hepatitis B infection (OBI) in Hong Kong blood donors is 0.1 % [1]. In this present study, we aimed to study the intrahepatic hepatitis B virus (HBV) DNA levels and the detectability of other serological markers, including the newly emerging Lumipulse G Hypersensitive and Quantitative hepatitis B surface antigen (HQ– HBsAg) and Lumipulse G hepatitis B core-related antigen (HBcrAg), in blood donors with OBI. Methods: Forty OBI blood donors, who had detectable HBV DNA and undetectable HBsAg by the Architect HBsAg assay (Abbott; detection limit 50 mIU/mL), were recruited for liver biopsies. Intrahepatic HBV DNA, covalently closed circular DNA (cccDNA), and pregenomic RNA (pgRNA) were assayed by real-time PCR [2]. HQ– HBsAg (detection limit 5 mIU/mL) and HBcrAg (detection limit 0.1 kU/mL) were measured using a chemiluminescent enzyme immunoassay in a Lumipulse G1200 analyzer (Fujirebio Inc., Tokyo, Japan). Serum HBV DNA was quantified using the Artus HBV RG Test (Qiagen).

Results: HQ–HBsAg and HBcrAg were detectable in 9 (23 %) and 4 (10 %) subjects, respectively. Eleven (28 %) subjects had detectable HQ–HBsAg and/or HBcrAg in the serum. The median histologic activity index and Ishak fibrosis score were 1 and 0, respectively. Intrahepatic total HBV DNA, cccDNA, and pgRNA was detectable in 30 (77 %), 1 (3 %) and 5 (13 %) subjects, respectively, with median levels of 0.35 copies/cell (range 0.007–18 copies/cell), 0.007 copies/ cell, and 0.001 copies/cell (range 0.0004–0.06 copies/cell), respectively. Eighteen (45 %) subjects had quantifiable serum HBV DNA ([1.1 IU/mL), with a median value of 2.6 IU/mL. Compared to subjects with undetectable HQ–HBsAg, subjects with detectable HQ– HBsAg had a higher median level of intrahepatic HBV DNA (0.07 vs. 1.02 copies/cell, respectively; P = 0.017) and higher median serum HBV DNA (1.1 vs. 6.6 IU/mL, respectively; P = 0.006). Conclusion: OBI was associated with normal liver histology. Low levels of serological and intrahepatic HBV replicative activity were detected in OBI subjects, and the levels of intrahepatic and serum HBV DNA correlated with the detectability of HQ–HBsAg. HQ– HBsAg and HBcrAg are potentially useful markers for the detection of HBV activity in these OBI subjects. Acknowledgements: The HQ–HBsAg (Lumipulse G HBsAg–HQ) and HBcrAg (Lumipulse G HBcrAg) measurements in this study were supported by Fujirebio Inc.