Tsuyoshi Hatakeyama

HBx protein is indispensable for development of viraemia in human hepatocyte chimeric mice.

The non-structural X protein, HBx, of hepatitis B virus (HBV) is assumed to play an important role in HBV replication. Woodchuck hepatitis virus X protein is indispensable for virus replication, but the duck hepatitis B virus X protein is not. In this study, we investigated whether the HBx protein is indispensable for HBV replication in vivo using human hepatocyte chimeric mice. HBx-deficient (HBx-def) HBV was generated in HepG2 cells by transfection with an overlength HBV genome. Human hepatocyte chimeric mice were infected with HBx-def HBV with or without hepatic HBx expression by hydrodynamic injection of HBx expression plasmids. Serum virus levels and HBV sequences were determined with mice sera. The generated HBx-def HBV peaked in the sucrose density gradient at points equivalent to the generated HBV wild type and the virus in a patients serum. HBx-def HBV-injected mice developed measurable viraemia only in continuously HBx-expressed liver. HBV DNA in the mouse serum increased up to 9 log(10) copies ml(-1) and the viraemia persisted for more than 2 months. Strikingly, all revertant viruses had nucleotide substitutions that enabled the virus to produce the HBx protein. It was concluded that the HBx protein is indispensable for HBV replication and could be a target for antiviral therapy.

Serum HBV RNA is a predictor of early emergence of the YMDD mutant in patients treated with lamivudine

Lamivudine (LAM) is a nucleoside analogue widely used for the treatment of chronic hepatitis B virus (HBV) infection. Emergence of resistant strains with amino acid substitutions in the tyrosine‐methionine‐aspartate‐aspartate (YMDD) motif of reverse transcriptase is a serious problem in patients on LAM therapy. The amount of covalently closed circular DNA in the serum is reported to be higher in patients who develop YMDD mutants than in those without mutants. However, there is no useful serum marker that can predict early emergence of mutants during LAM therapy. Analysis of patients who were treated with entecavir (n = 7) and LAM (n = 36) showed some patients had high serum levels of HBV RNA. Median serum levels of HBV RNA were significantly higher in patients in whom the YMDD mutant had emerged within 1 year (n = 6, 1.688 log copies/ml) than in those in whom the YMDD mutant emerged more than 1 year after treatment (n = 12, 0.456 log copies/ml, P = 0.0125) or in whom the YMDD mutant never emerged (n = 18, 0.688 log copies/ml, P = 0.039). Our results suggest that HBV RNA is a valuable predictor of early occurrence of viral mutation during LAM therapy. (HEPATOLOGY 2007;45:1179–1186.)

Absence of viral interference and different susceptibility to interferon between hepatitis B virus and hepatitis C virus in human hepatocyte chimeric mice

BACKGROUND/AIMS Both hepatitis B virus (HBV) and hepatitis C virus (HCV) replicate in the liver and show resistance against innate immunity and interferon (IFN) treatment. Whether there is interference between these two viruses is still controversial. We investigated the interference between these two viruses and the mode of resistance against IFN. METHODS We performed infection experiments with either or both of the two hepatitis viruses in human hepatocyte chimeric mice. Huh7 cell lines with stable production of HBV were also established and transfected with HCV JFH1 clone. Mice and cell lines were treated with IFN. The viral levels in mice sera and culture supernatants and messenger RNA levels of IFN-stimulated genes were measured. RESULTS No apparent interference between the two viruses was seen in vivo. Only a small (0.3 log) reduction in serum HBV and a rapid reduction in HCV were observed after IFN treatment, regardless of infection with the other virus. In in vitro studies, no interference between the two viruses was observed. The effect of IFN on each virus was not affected by the presence of the other virus. IFN-induced reductions of viruses in culture supernatants were similar to those in in vivo study. CONCLUSIONS No interference between the two hepatitis viruses exists in the liver in the absence of hepatitis. The mechanisms of IFN resistance of the two viruses target different areas of the IFN system.

Establishment of an infectious genotype 1b hepatitis C virus clone in human hepatocyte chimeric mice.

The establishment of clonal infection of hepatitis C virus (HCV) in a small-animal model is important for the analysis of HCV virology. A previous study developed models of molecularly cloned genotype 1a and 2a HCV infection using human hepatocyte-transplanted chimeric mice. This study developed a new model of molecularly cloned genotype 1b HCV infection. A full-length genotype 1b HCV genome, HCV-KT9, was cloned from a serum sample from a patient with severe acute hepatitis. The chimeric mice were inoculated intrahepatically with in vitro-transcribed HCV-KT9 RNA. Inoculated mice developed viraemia at 2 weeks post-infection, and this persisted for more than 6 weeks. Passage experiments indicated that the sera of these mice contained infectious HCV. Interestingly, a similar clone, HCV-KT1, in which the poly(U/UC) tract was 29 nt shorter than in HCV-KT9, showed poorer in vivo infectivity and replication ability. An in vitro study showed that no virus was produced in the culture medium from HCV-KT9-transfected cells. In conclusion, this study developed a genetically engineered genotype 1b HCV-infected mouse. This mouse model will be useful for the study of HCV virology, particularly the mechanism underlying the variable resistance of HCV genotypes to interferon therapy.

G to A hypermutation of TT virus

APOBEC3 proteins function as part of innate antiviral immunity and induce G to A hypermutation in retroviruses and hepatitis B virus (HBV) genomes. Whether APOBEC3 proteins affect viruses that replicate without a reverse transcription step is unknown. TT virus (TTV), known to present in serum of healthy individuals and HBV carriers, has a single-stranded circular DNA genome and replicates without reverse transcription. In this study, we examined 67 blood samples obtained from healthy individuals and HBV carriers and observed G to A hypermutation of genomes of TTV in both healthy individuals and HBV carriers. During ALT flare-up in HBV carriers, G to A hypermutation of HBV increased, but TTV genomes significantly decreased in number and hypermutated TTV genomes became undetectable. Our results show that hypermutated TTV exist in healthy individuals and HBV carriers and that TTV genomes were susceptible to immune reaction directed to HBV by interacting with APOBEC3 proteins.

Effects of structural variations of APOBEC3A and APOBEC3B genes in chronic hepatitis B virus infection.

Aim:  Human APOBEC3 deaminases induce G to A hypermutation in nascent DNA strand of hepatitis B virus (HBV) genomes and seem to operate as part of the innate antiviral immune system. We analyzed the importance of APOBEC3A (A3A) and APOBEC3B (A3B) proteins, which are potent inhibitors of adeno‐associated‐virus and long terminal repeat (LTR)‐retrotransposons, in chronic HBV infection.

Differential effects of interferon and lamivudine on serum HBV RNA inhibition in patients with chronic hepatitis B.

BACKGROUND Lamivudine and interferon have been widely used for the treatment of patients with chronic HBV infection. Serum HBV RNA is detected during lamivudine therapy as a consequence of interrupted reverse transcription and because RNA replicative intermediates are unaffected by the drug. In this study, we aimed to determine the detectability of serum HBV RNA during sequential combination therapy of interferon and lamivudine. METHODS HBV DNA and RNA in serum samples were quantified by reverse transcription of HBV nucleic acid extract and real-time PCR. Samples were analysed every 2 weeks to 3 months from three groups of patients: 10 male patients treated with nucleoside analogue monotherapy for 44-48 weeks (5 with lamivudine and 5 with entecavir), 6 males on sequential interferon and lamivudine combination therapy, and 3 males on lamivudine monotherapy for 20-24 weeks. RESULTS HBV RNA was not detectable in any patients before treatment, but became detectable in 15 during antiviral treatment. Among the three groups, pre-treatment HBV DNA (8.1 +/-2.4 versus 7.7 +/-1.4 versus 5.1 +/-0.3 log(10) copies/ml; P=0.06), treatment and follow-up durations (45.5 +/-2.0 versus 49.7 +/-5.6 versus 48.7 +/-6.4 weeks; P=0.32) were comparable. HBV RNA was detectable at the end of treatment or follow-up in all patients with monotherapy, but in none of those with sequential combination therapy (100% versus 0%; P<0.001). CONCLUSIONS Compared with lamivudine therapy with detectable serum HBV RNA in patients with chronic HBV infection, interferon treatment might reduce HBV DNA replication through the inhibition of HBV RNA replicative intermediates, resulting in the loss of serum HBV RNA.

Amino acid substitutions in core and NS5A regions of the HCV genome can predict virological decrease with pegylated interferon plus ribavirin therapy.

BACKGROUND The current standard therapy for chronic hepatitis C is pegylated interferon (PEG-IFN) plus ribavirin (RBV) combination therapy. Recently, it has been reported that amino acid (aa) substitutions in the core region, as well as the IFN-sensitivity-determining region (ISDR), were predictive of non-virological response (NVR), sustained virological response (SVR) and early virological response. Despite the importance of these two predictive factors for combination therapy, their interaction is poorly understood. METHODS A total of 117 patients who were treated with PEG-IFN-α2b plus RBV combination therapy were selected for participation in this study. We determined the aa sequences in the core region and ISDR by direct sequencing and analysed them along with clinical data to identify predictive factors for therapeutic response. RESULTS The aa sequences in the core region and γ-glutamyl transpeptidase (GTP) levels were associated with SVR and NVR, but aa sequences in the ISDR were not. However, substitutions at both aa 70 and aa 91 in the core region without substitutions in the ISDR and higher levels of γ-GTP were independent predictive factors for NVR. Wild-type aa 70 and aa 91 in the core region, higher platelet counts and lower levels of γ-GTP were independent predictive factors for SVR. CONCLUSIONS These results indicate that analyses of aa substitutions in both the core region and the ISDR are useful for predicting the effectiveness of combination therapy, and could help to avoid therapy exposure for patients who have a low probability of SVR.

Importance of Serum Concentration of Adefovir for Lamivudine-Adefovir Combination Therapy in Patients with Lamivudine-Resistant Chronic Hepatitis B

ABSTRACT Lamivudine (LMV)-adefovir pivoxil (ADV) combination therapy suppresses the replication of LMV-resistant hepatitis B virus (HBV), although its efficacy in suppressing HBV varies among patients. This study analyzed the clinical, virological, and pharmaceutical factors that influence the effect of the combination therapy. Patients negative for hepatitis B virus e antigen (HBeAg) and with low HBV DNA titers immediately prior to the combination therapy effectively cleared serum HBV DNA (P = 0.0348 and P = 0.0310, respectively). The maximum concentration of ADV in serum (ADV Cmax) was higher in patients who showed HBV DNA clearance (P = 0.0392), and the cumulative clearance rates of HBV DNA were significantly higher in patients with ADV Cmax equal to or greater than 24 ng/ml (P = 0.0284). HBeAg negativity and lower HBV DNA at the start of the combination therapy and higher ADV Cmax were found to be independent factors for serum HBV DNA clearance. Serum creatinine increased significantly during the combination therapy, and the ADV Cmax was higher in patients with low creatinine clearance rates. In conclusion, higher serum concentrations of ADV are associated with a good response to therapy based on clearance of HBV DNA in serum. However, care should be taken to prevent worsening of renal function due to high ADV serum concentrations.

Cheilitis granulomatosa as an early manifestation of Crohn's disease.

Cheilitis granulomatosa (CG) is a rare disease, which presents usually as a persistent swelling of the soft tissues in the orofacial region and is characterized histologically by a granulomatous inflammation. We report the case of a 19-year-old man who suffered from anal fistula. The patient had a 6-year history of asymptomatic and persistent swelling of the lower lip. Examinations for gastrointestinal lesions containing double-balloon total enteroscopy revealed erosions located longitudinally throughout the small intestine and the patient was diagnosed Crohn’s disease (CD). Biopsy of the lower lip showed non-caseating granuloma and confirmed the diagnosis of CG. Despite an elemental diet and mesalazine therapy, the lip swelling persisted. The CG can be the first presenting symptom of CD. CG as a complication of CD is discussed.