Combined small molecule and loss-of-function screen uncovers estrogen receptor alpha and CAD as host factors for HDV infection and antiviral targets.

OBJECTIVE: Hepatitis D virus (HDV) is a circular RNA virus coinfecting hepatocytes with hepatitis B virus. Chronic hepatitis D results in severe liver disease and an increased risk of liver cancer. Efficient therapeutic approaches against HDV are absent. DESIGN: Here, we combined an RNAi loss-of-function and small molecule screen to uncover host-dependency factors for HDV infection. RESULTS: Functional screening unravelled the hypoxia-inducible factor (HIF)-signalling and insulin-resistance pathways, RNA polymerase II, glycosaminoglycan biosynthesis and the pyrimidine metabolism as virus-hepatocyte dependency networks. Validation studies in primary human hepatocytes identified the carbamoyl-phosphatesynthetase 2, aspartate transcarbamylase and dihydroorotase (CAD) enzyme and estrogen receptor alpha (encoded by ESR1) as key host factors for HDV life cycle. Mechanistic studies revealed that the two host factors are required for viral replication. Inhibition studies using N-(phosphonoacetyl)-L-aspartic acid and fulvestrant, specific CAD and ESR1 inhibitors, respectively, uncovered their impact as antiviral targets. CONCLUSION: The discovery of HDV host-dependency factors elucidates the pathogenesis of viral disease biology and opens therapeutic strategies for HDV cure.

Hepatitis D virus replication is sensed by MDA5 and induces IFN-ß/λ responses in hepatocytes.

BACKGROUND & AIMS: Hepatitis B virus (HBV) and D virus (HDV) co-infections cause the most severe form of viral hepatitis. HDV induces an innate immune response, but it is unknown how the host cell senses HDV and if this defense affects HDV replication. We aim to characterize interferon (IFN) activation by HDV, identify the responsible sensor and evaluate the effect of IFN on HDV replication. METHODS: HDV and HBV susceptible hepatoma cell lines and primary human hepatocytes (PHH) were used for infection studies. Viral markers and cellular gene expression were analyzed at different time points after infection. Pattern recognition receptors (PRRs) required for HDV-mediated IFN activation and the impact on HDV replication were studied using stable knock-down or overexpression of the PRRs. RESULTS: Microarray analysis revealed that HDV but not HBV infection activated a broad range of interferon stimulated genes (ISGs) in HepG2NTCP cells. HDV strongly activated IFN-ß and IFN-λ in cell lines and PHH. HDV induced IFN levels remained unaltered upon RIG-I (DDX58) or TLR3 knock-down, but were almost completely abolished upon MDA5 (IFIH1) depletion. Conversely, overexpression of MDA5 but not RIG-I and TLR3 in HuH7.5NTCP cells partially restored ISG induction. During long-term infection, IFN levels gradually diminished in both HepG2NTCP and HepaRGNTCP cell lines. MDA5 depletion had little effect on HDV replication despite dampening HDV-induced IFN response. Moreover, treatment with type I or type III IFNs did not abolish HDV replication. CONCLUSION: Active replication of HDV induces an IFN-ß/λ response, which is predominantly mediated by MDA5. This IFN response and exogenous IFN treatment have only a moderate effect on HDV replication in vitro indicating the adaption of HDV replication to an IFN-activated state. LAY SUMMARY: In contrast to hepatitis B virus, infection with hepatitis D virus induces a strong IFN-ß/λ response in innate immune competent cell lines. MDA5 is the key sensor for the recognition of hepatitis D virus replicative intermediates. An IFN-activated state did not prevent hepatitis D virus replication in vitro, indicating that hepatitis D virus is resistant to self-induced innate immune responses and therapeutic IFN treatment.

Mouse models of hepatitis B and delta virus infection.

Liver disease associated to persistent infection with the hepatitis B virus (HBV) continues to be a major health problem of global impact. Therapeutic regimens currently available can efficiently suppress HBV replication; however, the unique replication strategies employed by HBV permit the virus to persist within the infected hepatocytes. As a consequence, relapse of viral activity is commonly observed after cessation of treatment with polymerase inhibitors. Among the HBV chronically infected patients, more than 15million patients are estimated to be co-infected with the hepatitis delta virus (HDV), a defective satellite virus that needs the HBV envelope for propagation. No specific drugs are currently available against HDV, while nucleos(t)ide analogs are not effective against HDV replication. Since chronic HBV/HDV co-infection leads to the most severe form of chronic viral hepatitis in men, a better understanding of the molecular mechanisms of HDV-mediated pathogenesis and the development of improved therapeutic approaches is urgently needed. The obvious limitations imposed by the use of great apes and the paucity of robust experimental models of HBV infection have hindered progresses in understanding the complex network of virus-host interactions that are established in the course of HBV and HDV infections. This review focuses on summarizing recent advances obtained with well-established and more innovative experimental mouse models, giving emphasis on the strength of infection systems based on the reconstitution of the murine liver with human hepatocytes, as tools for elucidating the whole life cycle of HBV and HDV, as well as for studies on interactions with the infected human hepatocytes and for preclinical drug evaluation.

Erectile dysfunction in patients with chronic viral hepatitis: a systematic review of the literature.

INTRODUCTION: This article reviews the literature on epidemiology and pathogenetic factors of erectile dysfunction in patients with chronic viral hepatic (CVH) diseases in men and the potential implications for diagnosis and treatment. AREAS COVERED: A search to identify original articles, reviews and any other article suitable for the purposes of this review was conducted by combining the following terms: erectile dysfunction and/or sexual dysfunction, chronic viral hepatitis, hepatitis B virus infection and hepatitis C virus infection. EXPERT OPINION: The results of this review have led to the following main observations: i) there is scarce documentation on the association between CVH and sexual dysfunction; ii) hormonal impairment seems to be a major component in the development of erectile dysfunction in CVH; however, published evidence concerning the contribution of other pathogenetic factors is rare and inconclusive and iii) available treatment options for CVH potentially contribute to the development of sexual dysfunction in these patients. Due to the scarce body of evidence, more research is needed to better clarify the mechanisms underlying the association between CVH and sexual dysfunction, the impact of therapy and associated comorbidities on sexual dysfunction and the role of pharmacological treatments in the management of these patients.

[Safety of atazanavir in patients with HIV and hepatitis B and/or C virus coinfection]. / Atazanavir en la coinfección por VIH y virus de la hepatitis B y/o C.

Atazanavir is a protease inhibitor indicated, in combination with other antiretrovirals, as an initial treatment of HIV infection or in previously treated patients. Antiretroviral treatment based on atazanavir has been associated with a low incidence of hepatotoxicity, both in Clinical Trials as well as in cohort studies. However, the finding of hyperbilirubinaemia has been common in these studies, although it usually does not involve withdrawing the treatment. In patients co-infected with hepatitis B or C, the level of virological response to does not appear to be affected and the incidence of adverse effects, except the higher incidence of hepatotoxicity, is no higher than in non-coinfected subjects. The incidence of severe hepatotoxicity (grade 3-4) in patients coinfected by HIV and HVC who receive drug combinations that contain atazanavir is 6%. Atazanavir has a favourable tolerance and safety profile in patients coinfected with hepatitis virus even in the presence of significant fibrosis. The lower association of atazanavir with the development of insulin resistance, a fact that has been associated with increasing the progression to hepatic fibrosis and lower treatment response rates, could be an added benefit of the use atazanavir in coinfected patients and could serve as an additional argument for its use in these patients.

[Apoptosis of peripheral blood lymphocytes in patients with chronic viral hepatitis]. / Apoptoz limfotsytiv peryferychnoï krovi u khvorykh na khronichnyi virusnyi gepatyt.

The examined 68 patients with chronic viral hepatitis (CVH) demonstrated a high Fas/APO-1 (CD95) expression on the peripheral blood lymphocytes. It correlated with the serum level of the tumor necrosis factor alpha (TNF alpha). The above findings suggest to us the implication of apoptosis in CVH pathogenesis. Following administration of interferonotherapy treatments the number of lymphocytes in the presence of apoptosis has gotten decreased.

Changing pattern of chronic hepatitis D in Southern Europe.

BACKGROUND & AIMS: The aim of this study was to assess changes in the clinical pattern of hepatitis D virus (HDV) infection in Italy, brought about by improved control of hepatitis B and D viruses, and to establish the natural history of chronic hepatitis D. METHODS: Histological diagnosis and clinical features of 122 patients with HDV recruited from 1987 to 1996 in three Italian tertiary referral centers (Torino, northern Italy; San Giovanni Rotondo and Castellana Grotte, southern Italy) were compared with those of 162 patients collected in the same centers in the previous decade. Patients from both groups with at least 6 months of follow-up were included in a new subgroup to assess the natural history of the disease. RESULTS: Among 162 patients referred from 1977 to 1986, 9 (6%) had mild hepatitis at histology vs. 9 (8%) of 122 patients referred in the second decade; 105 (65%) vs. 21 (17%) had severe hepatitis; 46 (28%) vs. 38 (31%) had histological asymptomatic cirrhosis; and 2 (1%) vs. 54 (44%) had clinically overt cirrhosis. For 159 patients (121 men and 38 women; mean age, 34 +/- 11), a follow-up of more than 6 months was documented, and they were included in the natural history subgroup. After 78 +/- 59 months of follow-up, 112 (70%) survived free of liver transplantation: 9 underwent transplantation, 32 died of liver failure, and 6 of acquired immunodeficiency syndrome. Estimated 5- and 10-year probability of survival free of orthotopic liver transplantation was 100% and 100% for patients with mild hepatitis, 90% and 90% for severe hepatitis, 81% and 58% for histological asymptomatic cirrhosis, and 49% and 40% for clinical cirrhosis (P < 0.01), respectively. CONCLUSIONS: Occurrence of fresh and severe forms of hepatitis D has diminished greatly in Italy. Contemporary patients represent cohorts infected years ago who survived the immediate medical impact of hepatitis D. The disease has been asymptomatic and nonprogressive in a minority; in the majority, it rapidly advanced to cirrhosis but thereafter subsided with stable clinical conditions for more than a decade.