Novel HBsAg markers tightly correlate with occult HBV infection and strongly affect HBsAg detection.

Occult HBV infection (OBI) is a threat for the safety of blood-supply, and has been associated with the onset of HBV-related hepatocellular carcinoma and lymphomagenesis. Nevertheless, genetic markers in HBsAg (particularly in D-genotype, the most common in Europe) significantly associated with OBI in vivo are missing. Thus, the goal of this study is to define: (i) prevalence and clinical profile of OBI among blood-donors; (ii) HBsAg-mutations associated with OBI; (iii) their impact on HBsAg-detection. OBI was searched among 422,278 blood-donors screened by Nucleic-Acid-Testing. Following Taormina-OBI-definition, 26 (0.006%) OBI-patients were identified. Despite viremia <50IU/ml, HBsAg-sequences were obtained for 25/26 patients (24/25 genotype-D). OBI-associated mutations were identified by comparing OBI-HBsAg with that of 82 chronically-infected (genotype-D) patients as control. Twenty HBsAg-mutations significantly correlated for the first time with OBI. By structural analysis, they localized in the major HBV B-cell-epitope, and in HBsAg-capsid interaction region. 14/24 OBI-patients (58.8%) carried in median 3 such mutations (IQR:2.0-6.0) against 0 in chronically-infected patients. By co-variation analysis, correlations were observed for R122P+S167L (phi=0.68, P=0.01), T116N+S143L (phi=0.53, P=0.03), and Y100S+S143L (phi=0.67, p<0.001). Mutants (obtained by site-directed mutagenesis) carrying T116N, T116N+S143L, R122P, R122P+Q101R, or R122P+S167L strongly decreased HBsAg-reactivity (54.9±22.6S/CO, 31.2±12.0S/CO, 6.1±2.4S/CO, 3.0±1.0S/CO and 3.9±1.3S/CO, respectively) compared to wild-type (306.8±64.1S/CO). Even more, Y100S and Y100S+S143L supernatants show no detectable-HBsAg (experiments in quadruplicate). In conclusions, unique HBsAg-mutations in genotype-D, different than those described in genotypes B/C (rarely found in western countries), tightly correlate with OBI, and strongly affect HBsAg-detection. By altering HBV-antigenicity and/or viral-particle maturation, they may affect full-reliability of universal diagnostic-assays for HBsAg-detection

Anti-HBV treatment induces novel reverse transcriptase mutations with reflective effect on HBV S antigen

The identification of novel reverse-transcriptase (RT) drug-resistance mutations is critical in predicting the probability of success to anti-HBV treatment. Furthermore, due to HBV-RT/HBsAg gene-overlap, they can have an impact on HBsAg-detection and quantification

Hepatitis {B} Virus Drug Resistance Tools: {One} Sequence, Two Predictions

Drug resistance testing, genotype analysis, and the determination of immune and vaccine escape variants support personalized antiviral treatment for hepatitis B patients. As phenotypic drug resistance testing for hepatitis B virus (HBV) is especially labor-intensive, due to the lack of simple cell culture systems, genotypic methods play a very pronounced role. The genetic structure of HBV allows the simultaneous analysis of two different genes by examination of a single region in the genome of HBV. Nevertheless, the overlapping open reading frames of the hepatitis B surface antigen (HBsAg) and the reverse transcriptase (RT) have to be interpreted separately. In diagnostic procedures, standard Sanger type sequencing (mostly performed as a dye-dideoxynucleotide terminator system) is still the most commonly used method. This allows using established techniques for interpreting those types of genetic information. Besides reviewing the foundation of drug resistance interpretation for HBV, different interpretation systems, either commercially available (TRUGENE, Abbott, ViroScore) or free to use (geno2pheno[HBV], HIV-GRADE HBV tool), are compared in this article. (C) 2014 S. Karger AG, Base

Häufigkeit von HBsAg (Hepatitis B surface-antigen) Mutationen in Isolaten resistenter Hepatitis B-Viren

The dorsal premotor cortex (dPMC) is a key region for motor learning and sensorimotor integration, yet we have limited understanding of its functional interactions with other regions. Previous work has started to examine functional connectivity in several brain areas using resting state functional connectivity (RSFC) and meta-analytical connectivity modelling (MACM). More recently, structural covariance (SC) has been proposed as a technique that may also allow delineation of functional connectivity. Here, we applied these three approaches to provide a comprehensive characterization of functional connectivity with a seed in the left dPMC that a previous meta-analysis of functional neuroimaging studies has identified as playing a key role in motor learning. Using data from two sources (the Rockland sample, containing resting state data and anatomical scans from 132 participants, and the BrainMap database, which contains peak activation foci from over 10,000 experiments), we conducted independent whole-brain functional connectivity mapping analyses of a dPMC seed. RSFC and MACM revealed similar connectivity maps spanning prefrontal, premotor, and parietal regions, while the SC map identified more widespread frontal regions. Analyses indicated a relatively consistent pattern of functional connectivity between RSFC and MACM that was distinct from that identified by SC. Notably, results indicate that the seed is functionally connected to areas involved in visuomotor control and executive functions, suggesting that the dPMC acts as an interface between motor control and cognition

Entecavir allows an unexpectedly high residual replication of HBV mutants resistant to lamivudine.

BACKGROUND: Entecavir is an efficient inhibitor of hepatitis B virus (HBV) reverse transcriptase (RT) and widely used for therapy of chronic hepatitis B. Entecavir treatment of HBV patients with Lamivudine-resistant viral strains, however, often fails, but the mechanism of cross-resistance development is not fully understood. METHODS: Using nonlinear regression models, dose response curves of cloned HBV strains from patients pre-treated with RT inhibitors were established in human hepatoma cell lines after transfection with HBV genomes containing HBV polymerase genes from patient isolates. 50% and 90% inhibitory concentrations (IC50, IC90) and antiviral resistance factors (RF50 and RF90) were calculated. RESULTS: The Entecavir dose-response curve of Lamivudine-resistant HBV RT mutants rtM204 for the replication of HBV decreased less than expected with increasing drug dose. Remarkably, due to the flat dose-response curves, RF90 values against Entecavir of samples with rtM204 substitutions were up to 30 times higher than their RF50 values. CONCLUSIONS: The unexpectedly high IC90 indicates a strong residual replication capacity of Lamivudine-resistant HBV rtM204 variants under Entecavir therapy, although IC50 values are initially within the therapeutic range of Entecavir. This characteristic favors rapid selection of additional mutants with overt resistance against Entecavir. Thus, the current phenotypic resistance assays should include determination of IC90