Article ID Journal Published Year Pages File Type
3374554 Journal of Infection 2015 11 Pages PDF
Abstract

•An integrative approach of sequence analyses, mathematical models and phenotypic assays was used in this work.•Novel HBsAg-genetic markers correlated with different levels of serum HBV-DNA in HBV chronically-infected patients.•Mutations compartmentalized at the C-terminus of the HBsAg correlated with HBV-DNA ≤2,000 UI/ml and low HBsAg titer.•The impact of such markers on the release of HBsAg has been validated with an in vitro model.

SummaryBackgroundTo define HBsAg-mutations correlated with different serum HBV-DNA levels in HBV chronically-infected drug-naive patients.MethodsThis study included 187 patients stratified into the following ranges of serum HBV-DNA:12–2000 IU/ml, 2000–100,000 IU/ml, and >100,000 IU/ml. HBsAg-mutations were associated with HBV-DNA levels by applying a Bayesian-Partitional-Model and Fisher-exact test. Mutant and wild-type HBV genotype-D genomes were expressed in Huh7 cells and HBsAg-production was determined in cell-supernatants at 3 days-post-transfection.ResultsSpecific HBsAg-mutations (M197T,-S204N-Y206C/H-F220L) were significantly correlated with serum HBV-DNA <2000 IU/ml (posterior-probability>90%, P < 0.05). The presence of Y206C/H and/or F220L was also associated with lower median (IQR) HBsAg-levels and lower median (IQR) transaminases (for HBsAg:250[115–840] IU/ml for Y206C/H and/or F220L versus 4300[640–11,838] IU/ml for wild-type, P = 0.023; for ALT:28[21–40] IU/ml versus 53[34–90] IU/ml, P < 0.001). These mutations were localized in the HBsAg C-terminus, known to be involved in virion and/or HBsAg secretion. The co-occurrence of Y206C + F220L was found significant by cluster-analysis, (P = 0.02). In addition, in an in-vitro model Y206C + F220L determined a 2.8–3.3 fold-reduction of HBsAg-amount released in supernatants compared to single mutants and wt (Y206C + F220L = 5,679 IU/ml; Y206H = 16,305 IU/ml; F220L = 18,368 IU/ml; Y206C = 18,680 IU/ml; wt = 14,280 IU/ml, P < 0.05).ConclusionsSpecific HBsAg-mutations (compartmentalized in the HBsAg C-terminus) correlated with low-serum HBV-DNA and HBsAg-levels. These findings can be important to understand mechanisms underlying low HBV replicative potential including the inactive-carrier state.

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Life Sciences Immunology and Microbiology Applied Microbiology and Biotechnology
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