Emerging concepts for the treatment of hepatitis delta

A mouse-adapted model of SARS-CoV-2 to test COVID-19 countermeasures

Coronaviruses are prone to transmission to new host species, as recently demonstrated by the spread to humans of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the coronavirus disease 2019 (COVID-19) pandemic1. Small animal models that recapitulate SARS-CoV-2 disease are needed urgently for rapid evaluation of medical countermeasures2,3. SARS-CoV-2 cannot infect wild-type laboratory mice owing to inefficient interactions between the viral spike protein and the mouse orthologue of the human receptor, angiotensin-converting enzyme 2 (ACE2)4. Here we used reverse genetics5 to remodel the interaction between SARS-CoV-2 spike protein and mouse ACE2 and designed mouse-adapted SARS-CoV-2 (SARS-CoV-2 MA), a recombinant virus that can use mouse ACE2 for entry into cells. SARS-CoV-2 MA was able to replicate in the upper and lower airways of both young adult and aged BALB/c mice. SARS-CoV-2 MA caused more severe disease in aged mice, and exhibited more clinically relevant phenotypes than those seen in Hfh4-ACE2 transgenic mice, which express human ACE2 under the control of the Hfh4 (also known as Foxj1) promoter. We demonstrate the utility of this model using vaccine-challenge studies in immune-competent mice with native expression of mouse ACE2. Finally, we show that the clinical candidate interferon-λ1a (IFN-λ1a) potently inhibits SARS-CoV-2 replication in primary human airway epithelial cells in vitro-both prophylactic and therapeutic administration of IFN-λ1a diminished SARS-CoV-2 replication in mice. In summary, the mouse-adapted SARS-CoV-2 MA model demonstrates age-related disease pathogenesis and supports the clinical use of pegylated IFN-λ1a as a treatment for human COVID-196.

Current concepts in acute liver failure

Acute liver failure (ALF) is a severe condition secondary to a myriad of causes associated with poor outcomes. The prompt diagnosis and identification of the aetiology allow the administration of specific treatments plus supportive strategies and to define the overall prognosis, the probability of developing complications and the need for liver transplantation. Pivotal issues are adequate monitoring and the institution of prophylactic strategies to reduce the risk of complications, such as progressive liver failure, cerebral oedema, renal failure, coagulopathies or infections. In this article, we review the main aspects of ALF, including the definition, diagnosis and complications. Also, we describe the standard-of-care strategies and recent advances in the treatment of ALF. Finally, we include our experience of care patients with ALF.

A mouse-adapted SARS-CoV-2 model for the evaluation of COVID-19 medical countermeasures

Coronaviruses are prone to emergence into new host species most recently evidenced by SARS-CoV-2, the causative agent of the COVID-19 pandemic. Small animal models that recapitulate SARS-CoV-2 disease are desperately needed to rapidly evaluate medical countermeasures (MCMs). SARS-CoV-2 cannot infect wildtype laboratory mice due to inefficient interactions between the viral spike (S) protein and the murine ortholog of the human receptor, ACE2. We used reverse genetics to remodel the S and mACE2 binding interface resulting in a recombinant virus (SARS-CoV-2 MA) that could utilize mACE2 for entry. SARS-CoV-2 MA replicated in both the upper and lower airways of both young adult and aged BALB/c mice. Importantly, disease was more severe in aged mice, and showed more clinically relevant phenotypes than those seen in hACE2 transgenic mice. We then demonstrated the utility of this model through vaccine challenge studies in immune competent mice with native expression of mACE2. Lastly, we show that clinical candidate interferon (IFN) lambda-1a can potently inhibit SARS-CoV-2 replication in primary human airway epithelial cells in vitro , and both prophylactic and therapeutic administration diminished replication in mice. Our mouse-adapted SARS-CoV-2 model demonstrates age-related disease pathogenesis and supports the clinical use of IFN lambda-1a treatment in human COVID-19 infections.

HDV infection in immigrant populations

AIMS

Little data have been published so far on the epidemiological aspects of hepatitis D virus (HDV) infection in immigrant populations and even poorer is the information on the virological, phylogenetic, and clinical aspects of this infection in these populations. This review article, aimed primarily at physicians caring for immigrants, summarizes the information available on HDV infection and analyzes data on this topic concerning the immigrant populations.

METHODS AND RESULTS

The prevalence of HDV infection in HBsAg-positive immigrants varies according to the country of origin. For example, in immigrants from sub-Saharan Africa, this prevalence is higher in those born in Equatorial Guinea (24.4%) than those from other African countries (10.3%). The epidemiological impact of HDV infection linked to migratory flows is a function of the different endemicity between countries of origin and countries in which a new existence has been established. This impact is high when immigrants from areas endemic to HDV infection (eg, Equatorial Guinea) settle in areas of low endemicity (eg, Germany or England, with a prevalence of around 4%), while the impact is lesser or nonexistent if the migratory flows are directed toward countries with intermediate endemicity (eg, Italy and Greece, with a prevalence of around 10%).

CONCLUSION

This impact of immigration on HDV epidemiology can be strong when HDV endemicity is high in the country of origin and low in the host country and slight when immigrants move to high or medium endemic countries.

Hepatitis D infection: from initial discovery to current investigational therapies

Hepatitis D is the most severe form of viral hepatitis associated with a more rapid progression to cirrhosis and an increased risk of hepatocellular carcinoma and mortality compared with hepatitis B mono-infection. Although once thought of as a disappearing disease, hepatitis D is now becoming recognized as a serious worldwide issue due to improvement in diagnostic testing and immigration from endemic countries. Despite these concerns, there is currently only one accepted medical therapy (pegylated-interferon-α) for the treatment of hepatitis D with less than desirable efficacy and significant side effects. Due to these reasons, many patients never undergo treatment. However, increasing knowledge about the virus and its life cycle has led to the clinical development of multiple promising new therapies that hope to alter the natural history of this disease and improve patient outcome. In this article, we will review the literature from discovery to the current investigational therapies.

HDV Can Constrain HBV Genetic Evolution in HBsAg: Implications for the Identification of Innovative Pharmacological Targets

Chronic HBV + HDV infection is associated with greater risk of liver fibrosis, earlier hepatic decompensation, and liver cirrhosis hepatocellular carcinoma compared to HBV mono-infection. However, to-date no direct anti-HDV drugs are available in clinical practice. Here, we identified conserved and variable regions in HBsAg and HDAg domains in HBV + HDV infection, a critical finding for the design of innovative therapeutic agents. The extent of amino-acid variability was measured by Shannon-Entropy (Sn) in HBsAg genotype-d sequences from 31 HBV + HDV infected and 62 HBV mono-infected patients (comparable for demographics and virological-parameters), and in 47 HDAg genotype-1 sequences. Positions with Sn = 0 were defined as conserved. The percentage of conserved HBsAg-positions was significantly higher in HBV + HDV infection than HBV mono-infection (p = 0.001). Results were confirmed after stratification for HBeAg-status and patients’ age. A Sn = 0 at specific positions in the C-terminus HBsAg were correlated with higher HDV-RNA, suggesting that conservation of these positions can preserve HDV-fitness. Conversely, HDAg was characterized by a lower percentage of conserved-residues than HBsAg (p < 0.001), indicating higher functional plasticity. Furthermore, specific HDAg-mutations were significantly correlated with higher HDV-RNA, suggesting a role in conferring HDV replicative-advantage. Among HDAg-domains, only the virus-assembly signal exhibited a high genetic conservation (75% of conserved-residues). In conclusion, HDV can constrain HBsAg genetic evolution to preserve its fitness. The identification of conserved regions in HDAg poses the basis for designing innovative targets against HDV-infection.

Molecular mechanisms of the preventable causes of cancer in the United States

Annually, there are 1.6 million new cases of cancer and nearly 600,000 cancer deaths in the United States alone. The public health burden associated with these numbers has motivated enormous research efforts into understanding the root causes of cancer. These efforts have led to the recognition that between 40% and 45% of cancers are associated with preventable risk factors and, importantly, have identified specific molecular mechanisms by which these exposures modify human physiology to induce or promote cancer. The increasingly refined knowledge of these mechanisms, which we summarize here, emphasizes the need for greater efforts toward primary cancer prevention through mitigation of modifiable risk factors. It also suggests exploitable avenues for improved secondary prevention (which includes the development of therapeutics designed for cancer interception and enhanced techniques for noninvasive screening and early detection) based on detailed knowledge of early neoplastic pathobiology. Such efforts would complement the current emphasis on the development of therapeutic approaches to treat established cancers and are likely to result in far greater gains in reducing morbidity and mortality.

HDV infection rates in northern Vietnam

Hepatitis D caused by the hepatitis delta virus (HDV) is a serious health problem in many regions of the world. A total of 546 HBV-infected patients were enrolled from 2013 to 2015 and classified clinically into the subgroups of chronic hepatitis B (CHB, n = 191), liver cirrhosis (LC, n = 147) and hepatocellular carcinoma (HCC, n = 208). The patients were screened for HDV-RNA by nested PCR assays. HDV genotypes were assessed by direct sequencing, followed by phylogenetic analysis. HDV-RNA was identified in 13% (71/546) of HBV-infected patients. The highest HDV prevalence was found in the LC group (19.7%), followed by the HCC (12%) and CHB (8.9%) groups (P = 0.017). HDV/HBV coinfections were significantly associated with a rather unfavourable clinical outcome, in particular with LC development compared to HBV monoinfection. Phylogenetic analyses indicated that the genotype HDV1 was, with a prevalence of 91%, by far the most common genotype in Vietnam, followed by HDV2 with 9%. Other HDV genotypes were not observed. In accordance with previous data obtained a decade ago, our results confirm a continuing high prevalence of HDV infection in hepatitis B patients in northern Vietnam with the HDV1 genotype still being the predominant genotype. HDV nucleic acid testing to minimize the associated risk should be considered.

Viral Hepatitis and Acute Liver Failure: Still a Problem

Although the overall prevalence is on the decline, viral hepatitis still plays a major role in the development of acute liver failure (ALF) worldwide. Hepatitis A, B, D, and E contribute to most fulminant viral courses. These viruses have not gained much attention in recent years yet remain relevant from a clinical perspective as the incidence in certain populations is on the increase. Other viral therapies and immunotherapies are currently being examined as treatments for hepatitis D and hepatitis E. Clinicians should still maintain a high index of suspicion for viral causes in approaching patients with ALF.

Hepatitis Delta Virus: Replication Strategy and Upcoming Therapeutic Options for a Neglected Human Pathogen

The human Hepatitis Delta Virus (HDV) is unique among all viral pathogens. Encoding only one protein (Hepatitis Delta Antigen; HDAg) within its viroid-like self-complementary RNA, HDV constitutes the smallest known virus in the animal kingdom. To disseminate in its host, HDV depends on a helper virus, the human Hepatitis B virus (HBV), which provides the envelope proteins required for HDV assembly. HDV affects an estimated 15-20 million out of the 240 million chronic HBV-carriers and disperses unequally in disparate geographical regions of the world. The disease it causes (chronic Hepatitis D) presents as the most severe form of viral hepatitis, leading to accelerated progression of liver dysfunction including cirrhosis and hepatocellular carcinoma and a high mortality rate. The lack of approved drugs interfering with specific steps of HDV replication poses a high burden for gaining insights into the molecular biology of the virus and, consequently, the development of specific novel medications that resiliently control HDV replication or, in the best case, functionally cure HDV infection or HBV/HDV co-infection. This review summarizes our current knowledge of HBV molecular biology, presents an update on novel cell culture and animal models to study the virus and provides updates on the clinical development of the three developmental drugs Lonafarnib, REP2139-Ca and Myrcludex B.