The biological properties of latent or occult hepatitis B virus (HBV) have been poorly characterized as a result of the extremely low virus concentration. This report describes the phenotype of HBV reactivating in two patients after an HBsAg-negative latency period. One patient had latent HBV infection for at least 12 years without detectable viremia and symptoms of liver disease. Several full-length HBV genomes were cloned at reactivation, sequenced, and functionally tested by transfection into HuH7 cells. Genomes from both patients showed a low replication phenotype. It was caused at the level of RNA encapsidation or HBV DNA synthesis, but was not attributable to uncommon mutations in the terminal protein domain of P protein.

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There is increasing evidence that certain pathogenic hepatitis B virus (HBV) variants may play a role in the pathogenesis of fulminant hepatitis (FHB). Recently, we isolated from a patient with fulminant recurrent hepatitis B after liver transplantation variants with enhanced replication competence and a possible defect in viral particle secretion. Both viral features may have contributed to the severity of the disease. The aim of this study was to prove the secretion defect of these variants, to analyze the consequences, and to identify the responsible viral mutations. The variant genomes and appropriate wild-type/variant hybrid genomes were functionally characterized after transfection in human hepatoma cells. Two cloned genomes and the polymerase chain reaction (PCR)-amplified mixture of full-length genomes showed a block in viral particle secretion. This was caused by a combination of amino acid changes in the Sprotein including the mutation G145R frequently emerging after hyperimmunoglobulin treatment. The mutations induced retention of the surface proteins in an endoplasmic reticulum (ER)-like compartment, but no intracellular accumulation. These data provide evidence for the in vivo existence of a dominant HBV population with a severe defect in The occurrence of hepatitis B virus (HBV) variants as minor or major viral populations in infected patients with fulminant, acute, and chronic hepatitis B was amply documented in the past. 1-5 HBV variants can differ from wild-type virus (WT) both in the DNA and viral protein sequences. Sequence variability and mutations were found in regulatory regions as well as in structural and nonstructural proteins. There is increasing evidence for a role of specific hepadnaviral variants in establishing chronic infection, virus/host cell interaction, and hepatopathogenesis. 4,5 In addition, several epidemic outbreaks of fulminant hepatitis B infections, which could be traced back to one chronically infected carrier, argue for an impact of viral variants in the pathogenesis of fulminant hepatitis (FHB). 6-9 Furthermore, it was shown that viral strains isolated from patients with FHB are particularly pathogenic for chimpanzees. 10 Three animals that were infected with serum of a child who transmitted FHB to 2 pediatricians developed severe hepatitis with unusually high transaminases for these animals. Based on the hypothesis that certain pathogenic HBV strains may cause or contribute to FHB several studies tried to identify structural characteristics of viral variants of these patients by determining the DNA and amino acid sequences of certain regions or the complete HBV genomes. 11-14 These experiments revealed that certain mutations, such as the precore stop codon mutation A-1896 and the core promoter mutations T-1762 and A-1764 occur more frequently in patients with FHB compared with chronic carriers, but no mutation specific for this disease course could be identified. However, this does not exclude a role of HBV variants in the pathogenesis of FHB because several differen...

The incidence of pancreatic ductal adenocarcinoma (PDAC) nearly equals its mortality rate, partly because most PDACs are intrinsically chemoresistant and thus largely untreatable. It was found recently that chemoresistant PDAC cells overexpress the Notch-2 receptor and have undergone epithelial-mesenchymal transition (EMT). In this study, we show that these two phenotypes are interrelated by expression of Midkine (MK), a heparin-binding growth factor that is widely overexpressed in chemoresistant PDAC. Gemcitabine, the front-line chemotherapy used in PDAC treatment, induced MK expression in a dose-dependent manner, and its RNAi-mediated depletion was associated with sensitization to gemcitabine treatment. We identified an interaction between the Notch-2 receptor and MK in PDAC cells. MK-Notch-2 interaction activated Notch signaling, induced EMT, upregulated NF-kB, and increased chemoresistance. Taken together, our findings define an important pathway of chemoresistance in PDAC and suggest novel strategies for its clinical attack. Cancer Res; 71(14);

Hepatitis B virus with a G145R mutation in the small surface protein is considered the quintessential immune escape mutant because it frequently is found in vaccinated individuals with breakthrough infections and liver transplant recipients under anti-hepatitis B surface antigen (HBsAg) immunoglobulin prophylaxis. Nowadays the prevalence of the variant progressively increases. However, because spread of a virus depends not only on immune pressure but also on the viral phenotype, we investigated the biologic properties of the G145R variant. The G145R mutation was introduced into wild-type (Wt) virus genome by in vitro mutagenesis. After transfection into human hepatoma cells, the DNA, RNA, and protein synthesis and viral secretion ability of the mutant were studied. Furthermore, cotransfection studies were performed with the G145R variant and a Wt virus S-protein expressing construct and vice versa. Production and stability of viral messenger RNAs (mRNAs), DNA, and proteins were not affected by the G145R mutation. In contrast, secretion of mutant virions was reduced significantly. Only 20% of virions were found in the medium of G145R variant-transfected cells compared with Wt virus. Furthermore, mutant virions were more sensitive to detergent treatment suggesting a diminished stability. In cotransfection studies, Wt virus S-protein rescued secretion of mutant virions, whereas mutant S-protein had a transdominant negative effect on secretion of Wt virus. Both mechanisms may support persistence of the defective mutant in a mixed population with Wt virus. In conclusion, the significant defect of the G145R mutant for secretion of infectious virions and the diminished stability of mutant virions may limit global spread of the mutant. H epatitis B virus (HBV) exhibits a mutation rate more than 4 orders of magnitude higher than that of other DNA viruses. 1 Naturally occurring variants may accumulate over time if they have a survival benefit over wild-type (Wt) virus, such as a higher ability to replicate DNA, an enhanced secretion ability, an increased infectivity or stability of virions, and so forth. In addition, certain variants may be selected under immune pressure or therapy with antiviral drugs.Nowadays, immune-escape variants that emerge under active and/or passive vaccination and are responsible for vaccination-breakthrough infections are of particular clinical relevance. Several such mutants carrying single or multiple amino acid substitutions in the major antigenic region of the virus, the a-determinant of the small surface protein, have been described. [2][3][4] The mutant by far most frequently detected all over the world in vaccinated individuals and liver transplant recipients treated with monoclonal or polyclonal anti-hepatitis B surface antigen (HBsAg) hyperimmunoglobulin carries a glycine to arginine substitution at amino acid position 145 (G145R). 3,[5][6][7][8][9][10][11] There is no doubt that despite selection of immuneescape variants, vaccination programs have so far been highly effective in reduci...

Two previous case reports suggest that hepatitis B virus (HBV) core promoter variants with a high replication competence contribute to the pathogenesis of fulminant hepatitis B (FHB). We recently found in HBV genomes from patients with FHB an accumulation of mutations within the core promoter region. Therefore, the aim of this study was to investigate the phenotype of these HBV variants. Replication competence and expression of hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) of viral genomes from seven patients with FHB and one patient with fulminant recurrent hepatitis after liver transplantation were analyzed by transfection experiments in human hepatoma cells. Compared with wild-type virus, the HBV variants from the seven patients with FHB produced similar or slightly lower levels of intracellular replicative intermediates and extracellular viral particles. In contrast, the HBV genomes from the patient with fulminant recurrent hepatitis synthesized and secreted significantly more HBV DNA. All genomes tested expressed similar or even higher levels of HBeAg compared with wild-type virus, except for those from four patients with a precore stop codon mutation in the respective dominant viral populations. The level of HBsAg produced by all variant genomes was similar or reduced compared with wild-type virus. These data indicate that in some cases HBV variants with enhanced replication competence and/or a defect in HBeAg expression may contribute to the development of FHB. However, neither phenotype is an essential prerequisite; thus, an additional role of other viral or host factors in the pathogenesis of FHB is suggested. (HEPATOLOGY 1998;28:1390-1397.)Approximately 1% of patients with hepatitis B virus (HBV) infection develop fulminant hepatitis B (FHB), which is characterized by rapid destruction of the liver parenchyma. More than 80% of these patients ultimately require liver transplantation or die of liver failure. The pathogenesis of FHB is not well understood so far. Viral factors and the host' s immune response may both play a role.In several previous investigations, the precore/core and core promoter regions of HBV genomes from patients with FHB were sequenced. Based on the findings of these studies, it was suggested that FHB is associated with a precore stop codon mutation (1896 G to A) 1-9 or with two mutations in the core promoter region (1762 A to T and 1764 G to A). 10,11 Both variants show a defect in hepatitis B e antigen (HBeAg) expression 12,13 that may modify the immune response of the host. 14,15 In addition, it has been proposed that the precore stop codon mutation and the T-1762/A-1764 substitutions also increase the replication efficiency of the virus. 12,13,16,17 However, in many cases of FHB, particularly those from nonendemic areas, 18-20 neither of these mutations was observed. The possible association of FHB with mutations in other parts of the HBV genome has recently been investigated by analysis of the entire nucleotide sequences of the HBV populations from such ...

We describe the development of an aggressive orthotopic metastatic model of esophageal cancer, which is visualized in real time with combined magnetic resonance imaging (MRI) and fluorescence imaging. The aim of the study was to describe the development of a novel model of metastatic tumor disease of esophageal carcinoma and use this model to evaluate fluorescence and MRI in early detection of local and metastatic disease. The human esophageal adenocarcinoma cell line PT1590 was stably transfected with green fluorescent protein (GFP). Nude mice were orthotopically implanted with PT1590-GFP cells. Orthotopic tumor growth as well as metastatic spread was examined by fluorescence imaging and high-resolution MRI at defined intervals after orthotopic implantation. Highly aggressive novel fluorescent cell lines were isolated from metastatic tissues and put into culture. After implantation of these cells, 100% of the animals developed orthotopic primary tumors. In 83% of animals, metastatic spread to liver, lung and lymph nodes was observed. Primary tumor growth could be visualized with fluorescence imaging and with MRI with high correlation between the 2 methods. Fluorescence imaging allows fast, sensitive, and economical imaging of the primary and metastatic tumor without anesthesia. With MRI, anatomical structures are visualized more precisely and tumors can be more accurately localized to specific organs. This model should prove highly useful to understand esophageal carcinoma and to identify novel therapeutics for this treatment-resistant disease.Esophageal carcinoma is one of the most common cancers in the world and, especially in the advanced stages, a leading cause of death. In the early stages, surgical resection is the only successful treatment. Survival is, however, mostly related to lymph node or distant organ metastases, and there is no effective therapeutic target for successfully treating metastasis. Therefore, understanding metastatic pathways and developing treatment options to reduce the size of the primary tumor and to treat or prevent metastatic spread is of greatest importance.Orthotopic models made by implanting histologically intact human tumor tissue into mice develop the local and metastatic behaviours occurring in human patients. 1-4 However, a metastatic orthotopic model of esophageal adenocarcinoma, which resembles the aggressive behavior in human disease, has not been established. Lack of such a model has been an impediment for the discovery and development of effective therapeutics for metastatic esophageal cancer.In addition, accurate and reproducible tumor imaging of orthotopic models can monitor the efficacy of novel therapeutics in real time. Multiple imaging techniques have been applied to small animal imaging. Previously, computed tomography, abdominal ultrasound and magnetic resonance imaging (MRI) have been used. A variety of newer imaging modalities such as in vivo fluorescence and bioluminescence imaging have now been established. [1][2][3][4] In addition, highresolution MRI with...

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