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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Full text 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:INVALID USER
Deposited On:22 Nov 2012 10:07
Last Modified:21 Jul 2014 08:18

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