Search Results (12)

Islatravir (ISL) is the first-in-class nucleoside reverse transcriptase translocation inhibitor (NRTtI) with novel modes of action. Data on ISL resistance are currently limited, particularly to HIV-1 non-B subtypes. This study aimed to assess prevalent nucleos(t)ide reverse transcriptase inhibitor (NRTI)-resistant mutations in HIV-1 subtype C for their phenotypic resistance to ISL. Prevalent single and combinations of NRTI-resistant mutations were selected from a routine HIV-1 genotypic drug resistance testing database and introduced into HIV-1 subtype C-like pseudoviruses, which were then tested for ISL susceptibility. Single NRTI-resistant mutations were susceptible or showed only a low level of resistance to ISL. This included thymidine analogue mutations (TAMs, i.e., M41L, D67N, K70R, T215FY, and K219EQ) and non-TAMs (i.e., A62V, K65R, K70ET, L74IV, A114S, Y115F, and M184V). Combinations of M184V with one or more additional NRTI-resistant mutations generally displayed reduced ISL susceptibilities. This was more prominent for combinations that included M184V+TAMs, and particularly M184V+TAM-2 mutations. Combinations that included M184V+K65R did not impact significantly on ISL susceptibility. Our study suggests that ISL would be effective in treating people living with HIV (PLWH) failing tenofovir disoproxil fumarate (TDF)/lamivudine (3TC) or TDF/emtricitabine (FTC)-containing regimens, but would be less effective in PLH failing zidovudine (AZT) with 3TC or FTC-containing regimens. Full article

Currently, interferon alpha and nucleos(t)ide analogues (NAs) are clinically available to treat hepatitis B virus (HBV) infection. Several NAs, including lamivudine (LMV), adefovir (ADV), entecavir (ETV) and tenofovir (TDF or TAF) have been approved and administered to chronic hepatitis B (CHB) patients. NAs inhibit HBV DNA synthesis by targeting the reverse transcriptase (RT) domain of HBV polymerase. Several mutations in the RT domain which lead to drug resistance against NAs have been reported, even for TDF and TAF which are highly potent with very low resistance rate. Besifovir (BFV) is a new antiviral dGMP analogue able to be used as a new NA drug for the control of CHB infection. Drug resistance to BFV is not well known due to its shorter duration of clinical use. Recently, we reported that rtL180M (M) and rtM204V (V) mutations, already resistant to LMV, are associated with BFV resistance. However, the susceptibility to BFV of previously known HBV mutants resistant to various drugs has not been studied. To investigate this, we performed in vitro drug susceptibility assays using natural and artificial mutants that are associated with resistance to LMV, ADV, ETV or TDF. As a result, LMV-resistant mutants were not susceptible to BFV and ETV-resistant clones showed partial resistance against BFV as well. However, ADV-resistant mutants were highly sensitive to BFV. In case of tenofovir-resistant mutations, the HBV mutants harboring primary mutations to tenofovir resistance were susceptible to BFV. Therefore, our study revealed that BSV may serve as an alternative drug for patients with ADV-, ETV-, TDF- or TAF-resistance. Full article

Chronic hepatitis induced by hepatitis B virus (HBV) infection is a serious public health problem, leading to hepatic cirrhosis and liver cancer. Although the currently approved medications can reliably decrease the virus load and prevent the development of hepatic diseases, they fail to induce durable off-drug control of HBV replication in the majority of patients. The roots of Isatis indigotica Fortune ex Lindl., a traditional Chinese medicine, were frequently used for the prevention of viral disease in China. In the present study, (−)-lariciresinol ((−)-LRSL), isolated from the roots of Isatis indigotica Fortune ex Lindl., was found to inhibit HBV DNA replication of both wild-type and nucleos(t)ide analogues (NUCs)-resistant strains in vitro. Mechanism studies revealed that (−)-LRSL could block RNA production after treatment, followed by viral proteins, and then viral particles and DNA. Promoter reporter assays and RNA decaying dynamic experiments indicated that (−)-LRSL mediated HBV RNA reduction was mainly due to transcriptional inhibition rather than degradation. Moreover, (−)-LRSL in a dose-dependent manner also inhibited other animal hepadnaviruses, including woodchuck hepatitis virus (WHV) and duck hepatitis B virus (DHBV). Combining the analysis of RNA-seq, we further found that the decrease in HBV transcriptional activity by (−)-LRSL may be related to hepatocyte nuclear factor 1α (HNF1α). Taken together, (−)-LRSL represents a novel chemical entity that inhibits HBV replication by regulating HNF1α mediated HBV transcription, which may provide a new perspective for HBV therapeutics. Full article

Several viral factors impact the natural course of hepatitis B virus (HBV) infection, the sensitivity of diagnostic tests, or treatment response to interferon-α and nucleos(t)ide analogues. These factors include the viral genotype and serotype but also mutations affecting the HBV surface antigen, basal core promoter/pre-core region, or reverse transcriptase. However, a comprehensive overview of the distribution of HBV variants between HBV genotypes or different geographical locations is lacking. To address this, we performed an in silico analysis of publicly available HBV full-length genome sequences. We found that not only the serotype frequency but also the majority of clinically relevant mutations are primarily associated with specific genotypes. Distinct mutations enriched in certain world regions are not explained by the local genotype distribution. Two HBV variants previously identified to confer resistance to the nucleotide analogue tenofovir in vitro were not identified, questioning their translational relevance. In summary, our work elucidates the differences in the clinical manifestation of HBV infection observed between genotypes and geographical locations and furthermore helps identify suitable diagnostic tests and therapies. Full article

Chronic hepatitis B virus (HBV) infection may be reactivated by immunosuppressive drugs in patients with autoimmune inflammatory rheumatic diseases. This study evaluates HBV serum markers’ prevalence in rheumatic outpatients belonging to Spondyloarthritis, Chronic Arthritis and Connective Tissue Disease diagnostic groups in Italy. The study enrolled 302 subjects, sex ratio (M/F) 0.6, mean age ± standard deviation 57 ± 15 years, 167 (55%) of whom were candidates for immunosuppressive therapy. The Spondyloarthritis group included 146 subjects, Chronic Arthritis 75 and Connective Tissue Disease 83 (two patients had two rheumatic diseases; thus, the sum is 304 instead of 302). Ten subjects (3%) reported previous anti-HBV vaccination and tested positive for anti-HBs alone with a titer still protective (>10 IU/mL). Among the remaining 292 subjects, the prevalence of positivity for HBsAg, isolated anti-HBc, anti-HBc/anti-HBs, and any HBV marker was 2%, 4%, 18%, and 24%, respectively. A total of 26/302 (9%) patients with γ-globulin levels ≤0.7 g/dL were more frequently (p = 0.03455) prescribed immunosuppressive therapy, suggesting a more severe rheumatic disease. A not negligible percentage of rheumatic patients in Italy are at potential risk of HBV reactivation related to immunosuppressive therapy. Before starting treatment, subjects should be tested for HBV markers. Those resulting positive should receive treatment or prophylaxis with Nucleos (t) ides analogue (NUCs) at high barrier of resistance, or pre-emptive therapy, according to the pattern of positive markers. HB vaccination is recommended for those who were never exposed to the virus. Full article

Over 257 million individuals worldwide are chronically infected with the Hepatitis B Virus (HBV). Nucleos(t)ide analogues (NAs) are the first-line treatment option for most patients. Entecavir (ETV) and tenofovir disoproxil fumarate (TDF) are both potent, safe antiviral agents, have a high barrier to resistance, and are now off patent. They effectively suppress HBV replication to reduce the risk of cirrhosis, liver failure, and hepatocellular carcinoma (HCC). Treatment is continued long-term in most patients, as NA therapy rarely induces HBsAg loss or functional cure. Two diverging paradigms in the treatment of chronic hepatitis B have recently emerged. First, the public health focussed “treat-all” strategy, advocating for early and lifelong antiviral therapy to minimise the risk of HCC as well as the risk of HBV transmission. In LMICs, this strategy may be cost saving compared to monitoring off treatment. Second, the concept of “stopping” NA therapy in patients with HBeAg-negative disease after long-term viral suppression, a personalised treatment strategy aiming for long-term immune control and even HBsAg loss off treatment. In this manuscript, we will briefly review the current standard of care approach to the management of hepatitis B, before discussing emerging evidence to support both the “treat-all” strategy, as well as the “stop” strategy, and how they may both have a role in the management of patients with chronic hepatitis B. Full article

We investigated Nucleos(t)ide-analogue (NA)-resistance mutations (mt) in 142 treatment-naive children with Chronic Hepatitis B (CHB), using a sensitive co-amplification at lower denaturation temperature (COLD)-PCR with Sanger DNA sequencing. An NA resistance-associated mt in the hepatitis B virus (HBV) reverse transcriptase (RT) was found in 66.2% of the patients, with nonclassical mt contributing the most (64.8%). Significantly higher frequencies of Lamivudine (LMV) and Adefovir dipivoxil (ADF) resistance-associated mt were found in genotypes B and C, respectively (OR_LMV/ADF: 1495.000; 95% CI: 89.800–24,889.032; p < 0.001). Single-point mt associated to LMV and ADF resistance were detected in 59.9% of the tested children with rtV207M (38.0%) and rtN238T (9.9%) being the most frequent. Multiple-point mt were found only in 8 cases (5.6%): 6 children carried double mt (rtV207M + rtL229V; rtV207M + rtI233V; rtV207I + rtV207M × 2 cases; rtV207M + rtS213T; rtN238A + rtS256G) relating to LMV or/and ADF resistance and 3 children carried triple mt (rtL180M + rtM204I + rtN238T; rtV207M + rtS213T + rtS256G) or quadruple mt (rtL180M + rtM204V + rtV207I/M) for LMV-ADF resistance and Entecavir-reduced susceptibility. Our data indicate that significantly higher frequencies of LMV and ADF-associated mutations were found in treatment-naïve children infected with HBV genotypes B and C, respectively. The developed COLD-PCR method and obtained data may contribute to the development of suitable treatments for children with CHB. Full article

Naturally occurring nucleos(t)ide analogue resistance (NUCr) substitution frequencies in the reverse transcriptase (RT) of the hepatitis B virus (HBV) were studied extensively after the clinical approval of nucleos(t)ide analogues (NUCs; year of approval 1998). We aimed to study NUCr substitutions in HBV RT sequences obtained before 1998 and better understand the evolution of RT sequences without NUC pressures. Our strategy was to retrieve HBV sequences from GenBank deposited before 1998. The initial search used the keywords “hepatitis B virus” or “HBV” and 1139 sequences were found. Data analyses included information extraction: sequence quality control and amino acid substitution analysis on 8 primary NUCr and 3 secondary substitution codons. Three hundred and ninety-four RT-containing sequences of 8 genotypes from 25 countries in 4 continents were selected. Twenty-seven (6.9%) sequences were found to harbor substitutions at NUCr-related codons. Secondary substitutions (rtL80V and rtV173G/A/L) occurred more frequently than primary NUCr substitutions (rtI169L; rtA181G; T184A/S; rtS202T/R; rtM204L and rtM250K). Typical amino acid substitutions associated with NUCr were of rtL80V, rtV173L and rtT184A/S. We confirm the presence of naturally occurring typical HBV NUCr substitutions with very low frequencies, and secondary substitutions are more likely to occur than primary NUCr substitutions without the selective pressure of NUCs. Full article

Chronic hepatitis B virus (HBV) infection is a major global health problem with an estimated 400 million HBV carriers worldwide. In the natural history of chronic hepatitis B (CHB), spontaneous acute exacerbation (AE) is not uncommon, with a cumulative incidence of 10%–30% every year. While exacerbations can be mild, some patients may develop hepatic decompensation and even die. The underlying pathogenesis is possibly related to the activation of cytotoxic T lymphocyte-mediated immune response against HBV. An upsurge of serum HBV DNA usually precedes the rise of alanine aminotransferase (ALT) and bilirubin. Whether antiviral treatment can benefit CHB with severe AE remains controversial, but early nucleos(t)ide analogues treatment seemed to be associated with an improved outcome. There has been no randomized study that compared the effects of different nucleos(t)ide analogues (NA) in the setting of CHB with severe AE. However, potent NAs with good resistance profiles are recommended. In this review, we summarized current knowledge regarding the natural history, pathogenetic mechanisms, and therapeutic options of CHB with severe AE. Full article

Hepatitis B often progresses to decompensated liver cirrhosis requiring orthotopic liver transplantation (OLT). Although newer nucleos(t)ide analogues result in >90% viral and hepatitis activity control, severely decompensated patients still need OLT because of drug-resistant virus, acute exacerbation, or hepatocellular carcinoma. Acute hepatitis B is also an indication for OLT, because it can progress to fatal acute liver failure. After OLT, the hepatitis B recurrence rate is >80% without prevention, while >90% of transplant recipients are clinically controlled with combined hepatitis B immunoglobulin (HBIG) and nucleos(t)ide analogue treatment. However, long-term HBIG administration is associated with several unresolved issues, including limited availability and extremely high cost; therefore, several treatment protocols with low-dose HBIG, combined with nucleos(t)ide analogues, have been investigated. Another approach is to induce self-producing anti-hepatitis B virus (HBV) antibodies using an HBV envelope (HBs) antigen vaccine. Patients who are not HBV carriers, such as those with acutely infected liver failure, are good candidates for vaccination. For chronic HBV carrier liver cirrhosis patients, a successful vaccine response can only be achieved in selected patients, such as those treated with experimentally reduced immunosuppression protocols. The present protocol for post-OLT HBV control and the future prospects of newer treatment strategies are reviewed. Full article

Hepatic diseases, like viral hepatitis, autoimmune hepatitis, hereditary hemochromatosis, non-alcoholic fatty liver disease (NAFLD) and Wilson’s disease, play an important role in the development of liver cirrhosis and, hence, hepatocellular carcinoma. In this review, the current treatment options and the molecular mechanisms of action of the drugs are summarized. Unfortunately, the treatment options for most of these hepatic diseases are limited. Since hepatitis B (HBV) and C (HCV) infections are the most common causes of liver cirrhosis and hepatocellular carcinoma, they are the focus of the development of new drugs. The current treatment of choice for HBV/HCV infection is an interferon-based combination therapy with oral antiviral drugs, like nucleos(t)ide analogues, which is associated with improving the therapeutic success and also preventing the development of resistances. Currently, two new protease inhibitors for HCV treatment are expected (deleobuvir, faldaprevir) and together with the promising drug, daclatasvir (NS5A-inhibitor, currently in clinical trials), adequate therapy is to be expected in due course (circumventing the requirement of interferon with its side-effects), while in contrast, efficient HBV therapeutics are still lacking. In this respect, entry inhibitors, like Myrcludex B, the lead substance of the first entry inhibitor for HBV/HDV (hepatitis D) infection, provide immense potential. The pharmacokinetics and the mechanism of action of Myrcludex B are described in detail. Full article

One year of interferon therapy inhibits HBV replication in one third of the patients whereas long-term administration of oral nucleos(t)ide analogues is efficient in most of them, as long as early treatment adaptation in patients with partial virological response and resistance is provided. Following the demonstration of a more potent antiviral effect in terms of sustained virological response (SVR) rates, Pegylated-IFN coupled with Ribavirin has become the standard treatment for chronic hepatitis C, with nearly 65% of all treated patients achieving a SVR. Long-term suppression of HBV and eradication of HCV would halt the progression of chronic hepatitis to cirrhosis, hepatocellular carcinoma and liver decompensation. Full article