Occult hepatitis B infection in blood donors from South East Asia: molecular characterisation and potential mechanisms of occurrence.

Candotti , Daniel and Lin, C Kit and Belkhiri, Dalila and Sakuldamrongpanich, Tasanee and Biswas, Subhajit and Lin, Sujen and Teo, Diana and Ayob, Yasmin and Allain, Jean-Pierre (2012) Occult hepatitis B infection in blood donors from South East Asia: molecular characterisation and potential mechanisms of occurrence. Gut, 61 (12). pp. 1744-1753. ISSN 0017-5749

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Official URL: http://dx.doi.org/10.1136/gutjnl-2011-301281

Abstract

Abstract

OBJECTIVE:
To investigate the molecular basis of occult hepatitis B virus (HBV) infection (OBI) in Asian blood donors.

DESIGN:
OBI donors from Hong Kong, Malaysia, Singapore, Taiwan and Thailand were tested for HBV serological markers, and strains were molecularly characterised.

RESULTS:
Among 138 confirmed OBI carriers (median age 47 years), HBV genotypes B and C were dominant (60% and 34%, respectively) in agreement with the genotype distribution in chronically infected donors in the region. Viral load ranged between unquantifiable and 3670 IU/ml (median 11 IU/ml). Eleven per cent of OBIs showed an unusual anti-HBs-only serological profile without evidence of past vaccination for most of these individuals. Occult HBV strains showed a higher genetic diversity than strains from matched hepatitis B surface antigen (HBsAg)+ donors, irrespective of genotype. No unique genetic signature or evidence of reduced replication competence was found. Mutations in the vicinity of the pre-S2/S splice donor site were common in OBI(B) (44%) and OBI(C) (36%) strains. S regions from four OBI cases were transfected in HuH7 cells. Results showed limited HBsAg secretion and suggested that mutations disrupting the splice donor site structure may affect pre-S2/S mRNA splicing.

CONCLUSIONS:
There is indirect evidence that incomplete immune control is involved in the occurrence of OBI in Asian blood donors infected with genotypes B and C as observed in Europe with genotype A2 but to a lower extent than with genotype D. A post-transcriptional mechanism may play a role in HBsAg expression in some OBIs irrespective of HBV genotype.

Item Type:Article
Keywords:occult hepatitis B virus, transfusion
Subjects:C Biological Sciences > C540 Virology
A Medicine and Dentistry > A300 Clinical Medicine
Divisions:College of Science > School of Life Sciences
ID Code:6897
Deposited By: Subhajit Biswas
Deposited On:22 Nov 2012 10:07
Last Modified:29 Nov 2013 14:12

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