Heinz-Hubert Feucht

Tenofovir for patients with lamivudine-resistant hepatitis B virus (HBV) infection and high HBV DNA level during adefovir therapy†‡§

Incomplete virological response to adefovir dipivoxil (ADV) has been observed in patients with lamivudine‐resistant hepatitis B virus (HBV) infection and may be associated with developing resistance and disease progression. We therefore investigated whether the efficacy of viral suppression could be improved by replacing ADV with tenofovir disoproxil fumarate (TDF). Twenty patients with chronic HBV infection (18 HBeAg+), viral breakthrough during lamivudine therapy, and persistent viral replication (>10 4 copies/mL) after 15 months of ADV monotherapy (range 4‐28 months) were treated with TDF 300 mg daily and were retrospectively analyzed. A screening for nucleoside/nucleotide analogue resistance mutations within the HBV polymerase gene was performed in all patients by direct sequencing. Within a median of 3.5 months, application of TDF led to undetectable HBV DNA in 19 of 20 patients, as demonstrated by suppression of HBV DNA below the detection limit of 400 copies/mL. Initially elevated ALT levels had normalized in 10 of 14 patients by the end of follow‐up (median 12 months, range 3‐24 months). Four patients lost HBeAg, after 3, 4, 5, and 16 months, and one patient seroconverted to anti‐HBs after 16 months of TDF therapy. Lamivudine‐associated mutations (rtV173L, rtL180M, rtM204V/I) could be detected in 6 patients at baseline of TDF, but this obviously did not influence the response. ADV‐resistant mutations were not detected. No side effects were reported. In conclusion, these preliminary observations strongly suggest that TDF might be a highly effective rescue drug for HBV‐infected patients with altered responsiveness to treatment with lamivudine and ADV. (HEPATOLOGY 2006;44:318–325.)

Long‐term efficacy of tenofovir monotherapy for hepatitis B virus‐monoinfected patients after failure of nucleoside/nucleotide analogues

Tenofovir disoproxil fumarate (TDF) has demonstrated high antiviral efficacy in treatment‐naive patients with chronic hepatitis B virus (HBV) infection but experience in nucleoside/nucleotide analogue (NA)‐experienced patients is limited. In this retrospective multicenter study we therefore assessed the long‐term efficacy of TDF monotherapy in patients with prior failure or resistance to different NA treatments. Criteria for inclusion were HBV DNA levels >4.0 log10 copies/mL at the start and a minimum period of TDF therapy for at least 6 months. In all, 131 patients (mean age 42 ± 12 years, 95 male, 65% hepatitis B e antigen [HBeAg]‐positive) were eligible. Pretreatment consisted of either monotherapy with lamivudine (LAM; n = 18), adefovir (ADV; n = 8), and sequential LAM‐ADV therapy (n = 73), or add‐on combination therapy with both drugs (n = 29). Three patients had failed entecavir therapy. Resistance analysis in 113 of the 131 patients revealed genotypic LAM and ADV resistance in 62% and 19% of patients, respectively. The mean HBV DNA level at TDF baseline was 7.6 ± 1.5 log10 copies/mL. The overall cumulative proportion of patients achieving HBV DNA levels <400 copies/mL was 79% after a mean treatment duration of 23 months (range, 6–60). Although LAM resistance did not influence the antiviral efficacy of TDF, the presence of ADV resistance impaired TDF efficacy (100% versus 52% probability of HBV DNA <400 copies/mL, respectively). However, virologic breakthrough was not observed in any of the patients during the entire observation period. Loss of HBeAg occurred in 24% of patients and HBsAg loss occurred in 3%. No significant adverse events were noticed during TDF monotherapy. Conclusion: TDF monotherapy induced a potent and long‐lasting antiviral response in NA‐experienced patients with previous treatment failure. Our data may have implications for current add‐on strategies. (HEPATOLOGY 2009.)

Biofilm Formation by Staphylococcus epidermidis Depends on Functional RsbU, an Activator of the sigB Operon: Differential Activation Mechanisms Due to Ethanol and Salt Stress

Staphylococcus epidermidis is a common pathogen in medical device-associated infections. Its major pathogenetic factor is the ability to form adherent biofilms. The polysaccharide intercellular adhesin (PIA), which is synthesized by the products of the icaADBC gene cluster, is essential for biofilm accumulation. In the present study, we characterized the gene locus inactivated by Tn917 insertions of two isogenic, icaADBC-independent, biofilm-negative mutants, M15 and M19, of the biofilm-producing bacterium S. epidermidis 1457. The insertion site was the same in both of the mutants and was located in the first gene, rsbU, of an operon highly homologous to the sigB operons of Staphylococcus aureus and Bacillus subtilis. Supplementation of Trypticase soy broth with NaCl (TSB(NaCl)) or ethanol (TSB(EtOH)), both of which are known activators of sigB, led to increased biofilm formation and PIA synthesis by S. epidermidis 1457. Insertion of Tn917 into rsbU, a positive regulator of alternative sigma factor sigma(B), led to a biofilm-negative phenotype and almost undetectable PIA production. Interestingly, in TSB(EtOH), the mutants were enabled to form a biofilm again with phenotypes similar to those of the wild type. In TSB(NaCl), the mutants still displayed a biofilm-negative phenotype. No difference in primary attachment between the mutants and the wild type was observed. Similar phenotypic changes were observed after transfer of the Tn917 insertion of mutant M15 to the independent and biofilm-producing strain S. epidermidis 8400. In 11 clinical S. epidermidis strains, a restriction fragment length polymorphism of the sigB operon was detected which was independent of the presence of the icaADBC locus and a biofilm-positive phenotype. Obviously, different mechanisms are operative in the regulation of PIA expression in stationary phase and under stress induced by salt or ethanol.

20-fold increase in risk of lamivudine resistance in hepatitis B virus subtype adw.

We investigated subtype-dependent development of lamivudine resistance in hepatitis B virus (HBV) longitudinally in 26 consecutive patients (13 adw and 13 ayw carriers) during antiviral treatment of chronic hepatitis B. Lamivudine resistance developed in seven adw carriers and one ayw carrier. Risk of lamivudine resistance was significantly higher for adw carriers than for ayw carriers (p=0.03). We believe that the adw subtype of HBV is associated with a high risk of lamivudine resistance, which might be linked to simultaneous changes of the HBsAg that occurs with the emergence of resistance.

Viral features of lamivudine resistant hepatitis B genotypes A and D

Viral differences among lamivudine resistant hepatitis B (HBV) genotypes have not been yet investigated. Therefore, we analyzed the characteristics of these viral strains in vivo. Forty‐one patients carrying lamivudine resistant HBV were enrolled. Twenty‐six patients (63%) carried resistant HBV genotype A (group A) and 15 patients (37%) carried resistant HBV genotype D (group D). The rate of reverse transcriptase 204I mutants was significantly higher in group D (67%) compared with group A (19%), whereas rt204V mutants (81% in group A vs 33% in group D; P = .006) and rt180M mutants (81% in group A vs 40% in group D, P = .015) prevailed in group A. The median time of shift from rt204I to rt204V mutants was significantly shorter in group A (4 months in group A, >12 months in group D, P < .001). Additional resistance associated mutations were detected exclusively in group D (P = .004). In a multivariate analysis, HBV genotype (P = .039) and pretreatment serum HBV DNA (P = .001) were independently associated with emerging rt204I or rt204V mutants, respectively. Serum HBV copy numbers after emergence of resistance were higher in group A (mean log10 6.99 copies/ml; range 3–9) compared with group D (mean log10 6.1 copies/ml; range 3.3–8; P = .04). There was no difference between both groups regarding core promoter/precore mutations, viral turnover, and number of flares or disease progression during follow‐up. In conclusion, the mutational pattern during selection of lamivudine resistant HBV strains differs between genotypes A and D. This may have consequences for a salvage regimen initiated for treatment of lamivudine resistant HBV. (HEPATOLOGY 2004;39:42–50.)

Low Risk of Vertical Transmission of Hepatitis C Virus by Breast Milk

To evaluate the risk of hepatitis C virus (HCV) transmission via breast milk, we collected 76 samples of breast milk from 73 chronically HCV-infected women and serum samples from their 76 perinatally HCV-exposed children. Enzyme immunoassay and strip immunoblot assay were used for detection of antibodies to HCV, and reverse transcriptase-polymerase chain reaction analysis was used for detection of HCV RNA. None of the 76 samples of breast milk contained HCV RNA, whereas 37 (59.7%) of 62 mothers tested for HCV RNA had HCV viremia. Only 1 of the 76 breast-fed infants had evidence of HCV infection. Because HCV infection in this child was detected 1 month after birth, it seems unlikely that it was transmitted by breast-feeding. These results indicate that HCV infection in pregnant women should not be a contra-indication for breast-feeding.

Genotyping of hepatitis C virus types 1, 2, 3, and 4 by a one-step LightCycler method using three different pairs of hybridization probes

ABSTRACT Determination of hepatitis C virus (HCV) genotypes has become increasingly important during the last years for prediction of the clinical course and the outcome of antiviral therapy. Therefore, numerous different methods have been developed to enable HCV genotyping. However, many of them are very laborious and expensive, leading to limited usage in daily routine diagnostics. We have established a method which combines the speed of the new LightCycler technology with the use of amplification products generated for diagnostic quantitative HCV RNA determination. Differentiation of HCV genotypes is performed with these amplicons in a single step by using fluorophore-labeled hybridization probes. Although currently only two different acceptor fluorophores are available for the LightCycler, types 1, 2, 3, and 4, which are by far the prevailing HCV genotypes in Europe and the United States, can be distinguished. Genotypes of specimens from 190 chronically HCV-infected patients were determined by the LightCycler method and compared with the results of nucleotide sequencing. Concordant results were obtained for all samples. This new method offers a fast and convenient possibility to determine the quantitative HCV RNA load and the genotype in large-scale settings within about 4 h.

Epidemiological Dynamics of Hepatitis C Virus among 747 German Individuals: New Subtypes on the Advance

ABSTRACT This study demonstrates the dynamics in the epidemiology of hepatitis C virus subtypes. Subtypes 3a and 4a have become increasingly prevalent in patients where an infection within recent years can be assumed. Evidence is presented that the subtypes observed among younger patients can spread rapidly and lead to significant changes in the subtype distribution.

Subtype-Dependent Response of Hepatitis B Virus during the Early Phase of Lamivudine Treatment

We conducted a 12-month longitudinal investigation of the subtype-dependent response of hepatitis B virus (HBV) to lamivudine treatment in 43 consecutive patients with chronic hepatitis B. HBV subtype ayw appears to respond better to lamivudine monotherapy than does HBV subtype adw (P=.005). This might be the reason for the lower incidence of lamivudine-resistant strains observed in persons infected with HBV subtype ayw during follow-up.

Quantitative Detection of Hepatitis C Virus RNA by Light Cycler PCR and Comparison with Two Different PCR Assays

ABSTRACT The new Light Cycler technology was adapted to the detection of hepatitis C virus (HCV) RNA in clinical samples. Sera from 81 patients were tested by Light Cycler PCR, AMPLICOR HCV Monitor assay, and in-house PCR. Our data demonstrate that Light Cycler is a fast and reliable method for the detection and quantitation of HCV RNA.