Alternative hepatitis B virus DNA confirmatory algorithm identified occult hepatitis B virus infection in Chinese blood donors with non-discriminatory nucleic acid testing.

Background: Multiplex viral nucleic acid testing (NAT) and a discriminatory testing algorithm have been used to detect viral infections in blood donors. Non-discriminated reactive (NDR) results may arise from low hepatitis B virus (HBV) DNA levels and are challenging for donor management by blood services. The aim of this study was to evaluate the performance and feasibility of alternative viral particle concentration methods to confirm and to characterise HBV infection status in NDR donors from Dalian, China, in order to improve routine donor management according to the potential residual risk estimate.

Materials And Methods: Individual donations were tested with ULTRIO Plus, and discriminated when reactive. Virions were concentrated from 12 and 6 mL plasma samples by ultracentrifugation (UC) and polyethylene glycol (PEG) precipitation, respectively. HBV DNA was detected with four nested polymerase chain reactions (95% limit of detection: 5-25 IU/mL). Amplified products were sequenced for definitive confirmation. Anti-HBc and anti-HBs were tested.

Results: Of 77,556 donors, 79 (0.1%) were NAT NDR. After viral particle concentration by UC and PEG precipitation, HBV DNA was detected in 46 (58.2%) and 34 (43.0%) NDR donors, respectively, including 61.7% of samples that were repeatedly non-reactive with multiple NAT testing. Anti-HBc and anti-HBs (median titre: 37 mIU/mL) were detected in 87.3% and 46.8% of NDR donors, respectively. Sequencing confirmed HBV DNA in 65.8% of NDR donors, of whom 96.2% were occult HBV carriers with rare mutations in S and core proteins.

Discussion: A HBV DNA confirmatory procedure with limited technical constraints was implemented successfully. The majority of NDR donors had occult HBV infections with extremely low viral DNA levels, which may constitute a potential residual threat for blood safety. Only a minority of anti-HBc+ NDR donors had anti-HBs levels high enough to consider their reinstatement as donors. The data support the permanent deferral of NDR donors to ensure maximum blood safety in areas of high HBV endemicity.