Impact of HBV genotype and mutations on HBV DNA and qHBsAg levels in patients with HBeAg-negative chronic HBV infection.

BACKGROUND: HBV DNA and quantitative (q)HBsAg levels as prognostic markers for HBV-related disease are mostly validated in Asia and their significance in Western populations is uncertain. AIM: To analyse the impact of the HBV genotype and frequent mutations in precore (PC), basal core promoter (BCP) and preS on HBV DNA and qHBsAg levels. METHODS: HBV DNA and qHBsAg serum levels of 465 patients with HBeAg-negative chronic HBV infection were correlated with the HBV genotype and mutations in PC, BCP and preS. For a detailed analysis of the molecular virology, genotype A2 genomes harbouring these mutations were analysed for replication efficacy and HBsAg release in cell culture. RESULTS: While no impact of the HBV genotype on HBV DNA levels was observed, qHBsAg levels differed up to 1.4 log among the genotypes (P < 0.001), reflected by large differences regarding the 1000 IU/mL HBsAg cut-off. While PC mutations were associated with higher (P < 0.001), BCP mutations were associated with lower HBV DNA levels (P < 0.001). Higher qHBsAg levels were associated with preS and lower levels with PC mutations (P < 0.001 and P = 0.001, respectively). The cell culture experiments revealed a higher HBsAg release and shorter filaments in case of a HBV genome harbouring a preS deletion. In contrast, a perinuclear HBsAg accumulation was detected for the PC and BCP-variants, reflecting an impaired HBsAg release. CONCLUSIONS: qHBsAg serum levels depend on the HBV genotype and together with HBV DNA levels on frequent mutations in PC, BCP and preS in HBeAg-negative patients. qHBsAg cut-offs when used as prognostic markers require genotype-dependent validation.

IL28B gene variants and glucose metabolism in Type 2 Diabetes.

Type 2 Diabetes (T2D) develops, when ß-cell insulin response fails to compensate for insulin resistance. Recent studies reported associations between the IL28B polymorphisms (rs12979860 and rs8099917) and T2D development in Hepatitis C virus (HCV) patients. To identify possible association with T2D independent from virus infection, we investigated both IL28B polymorphisms in T2D patients and healthy controls (HC). No association was found comparing the genotype and allele frequencies of both IL28B polymorphisms between T2D patients and HC. However, higher glucose levels were found in T2D patients carrying the IL28B CT/TT rs12979860 and GT/GG rs8099917 HCV risk genotypes compared to those with the protective CC and TT genotype (p=0.06 and p=0.02, respectively). Moreover, T2D patients with CT/TT rs12979860 HCV risk genotypes possessed significantly higher HbA1c levels than CC carriers (p=0.04). In conclusion, the IL28B HCV risk genotypes may influence glucose homeostasis in T2D patients without HCV.

Serum microRNA-122 kinetics in patients with chronic hepatitis C virus infection during antiviral therapy.

The levels of the liver-specific microRNA-122 (miR-122) circulating extracellularly in the blood have been shown to be increased upon liver damage. However, it is unknown if the levels of serum miR-122 are altered during antiviral therapy and reflect the therapeutic success. Here, we investigated miR-122 serum levels in patients with chronic hepatitis C virus (HCV) genotype 1 infection during antiviral therapy with pegylated interferon and ribavirin. Therefore, sera from 60 patients with chronic HCV infection genotype 1 showing sustained virological response (SVR), non-response or relapse to therapy obtained at baseline, 4, 12, 24 weeks, end of treatment and follow-up were analysed retrospectively for miR-122 content by quantitative real-time reverse transcription PCR. The time courses of miR-122 were correlated with HCV RNA as well as standard liver parameters. We found that while there was no relation between serum miR-122 and HCV RNA levels at baseline, the decline in HCV RNA upon beginning of the therapy closely correlated with the reduction of serum miR-122 in the three different patient groups. Moreover, the serum miR-122 level correlated well with alanine aminotransaminase, a marker of ongoing liver damage. At follow-up serum miR-122 levels remained low in SVR, but increased to baseline levels in patients not responding or showing relapse to therapy. In contrast, the serum concentration of the ubiquitously expressed miR-16 did not change during therapy. We conclude that the serum level of miR-122 well reflects the success of interferon/ribavirin therapy in patients with chronic HCV infection.

Dynamics of hepatitis B virus quasispecies heterogeneity and virologic response in patients receiving low-to-moderate genetic barrier nucleoside analogs.

We characterized the early dynamics of hepatitis B virus (HBV) quasispecies evolution during the first weeks of antiviral therapy with low-to-moderate genetic barrier antiviral drugs and associated these data with antiviral response patterns. Fifteen chronic hepatitis B patients (men, 10; mean age, 34; HBeAg positive, 6) who received lamivudine or telbivudine for at least 52 weeks were included. HBV DNA was extracted from serum, and a 910-bp fragment covering domains A-F of the reverse transcriptase region was amplified, cloned and sequenced. Parameters of quasispecies heterogeneity, genetic diversity and complexity were calculated and were correlated with complete virologic response, defined as undetectable HBV DNA at week 52. Nine patients achieved complete virologic response during the observational period. While baseline HBV DNA levels and HBeAg status were associated with virologic response, baseline quasispecies complexity and diversity of responders showed no significant difference to those of nonresponders (P > 0.05). However, at week 4, quasispecies complexity of nonresponders was significantly higher compared with that of responders on the nucleotide level (P = 0.01) and the aa level (P = 0.04). The number of synonymous substitutions per synonymous site dropped significantly in responders at week 4 (P = 0.04), while there was no difference in nonresponders. The HBV quasispecies complexity at the early stage of antiviral therapy (week 4) with the low-to-moderate genetic barrier nucleoside analogs lamivudine or telbivudine was associated with subsequent virologic response. Further studies are needed to confirm HBV quasispecies evolution as additional predictive marker for beneficial treatment outcome.

Modulation of replication efficacy of the hepatitis C virus replicon Con1 by site-directed mutagenesis of an NS4B aminoterminal basic leucine zipper.

The hepatitis C virus (HCV) nonstructural protein 4B (NS4B) is assumed to function as a membrane anchor and protein hub for the viral replication complex. The aim of the current work was to modulate HCV replication efficacy in the subgenomic Con1 replicon by mutations of specific sites within the aminoterminal-located basic leucine zipper (bZIP), a candidate motif for protein-protein interactions involving NS4B. Mutational sites and amino acid substitutes were determined by in-silico sequence analyses of the NS4B-bZIP motif in 357 isolates of HCV genotype 1b from the euHCVdB and LosAlamos database and consecutive analysis of conserved physico-chemical properties at bZIP specific positions. Mutants with predicted minor, medium or major reduction of replication efficacy were tested in the pFKI389neo/NS3-3'/ET plasmid replicon model. Four sites (L25, T29, V39 and W43) of crucial importance for bZIP-mediated protein interaction with predicted apolarity of respective amino acid positions were selected for mutational studies. Substitutes with physico-chemical properties matching the predicted requirements either well (T29A), moderately (L25W, V39W), or insufficiently (T29E, W43E) were associated with slightly improved, moderate and marked decreased replication efficacy, respectively. Spontaneous (T29G) and adaptive (A28G, E40G) mutations occurred in the T29E mutation isolate only and were associated with marked reduction of replication efficacy. The bZIP motif region of NS4B is crucial for RNA replication in the subgenomic Con1 replicon system. RNA replication efficacy can be modulated by site-directed mutagenesis at specific bZIP functional sites. New adaptive amino acid mutations were identified within the HCV NS4B protein.

Mutations selected in the hepatitis C virus NS3 protease domain during sequential treatment with boceprevir with and without pegylated interferon alfa-2b.

Treatment with hepatitis C virus (HCV)-NS3-protease inhibitors lead to the selection of resistant variants. Viral kinetics and resistance profiles in patients who are re-treated with the same protease inhibitor are unknown. Viral kinetics and NS3-resistance mutations obtained by clonal sequencing of the NS3-protease were analyzed in nine HCV-genotype-1-infected nonresponder patients who were sequentially treated with boceprevir (400 mg t.i.d.) for 1 week, peginterferon-alfa-2b for 2 weeks and combination of the two for 2 weeks in varying order. In addition to predominant wild-type isolates, previously described boceprevir-resistant mutations (V36, T54, R155, A156, V170) were observed. Furthermore, two resistant mutations (Q41, F43) were detected for the first time in vivo. In three patients, mutations selected after initial treatment with boceprevir were re-selected during subsequent boceprevir exposure. However, mutational patterns after the first and second exposure to boceprevir were different in five patients. In one patient, a viral variant (V55A) known to reduce susceptibility to boceprevir was the predominant variant observed at baseline and throughout treatment and was associated with a shallow viral decline. Different resistance mutations were selected during treatment with boceprevir ± peginterferon. Sequential short-term dosing of boceprevir was not associated with accumulation of resistant variants but pre-existing variants may impair virologic response.