Michael Kann

• MD
• Professor at University of Gothenburg

Hepatitis B virus (HBV) is a major global health concern, affecting millions of people worldwide. HBV is part of the hepadnaviridae family and one of the primary causes of acute and chronic liver infections, leading to conditions such as cirrhosis and hepatocellular carcinoma (HCC). Understanding the intracellular transport and genome repair mechan...

This study utilized digital PCR to quantify HBV RNA and HBV DNA within three regions of the HBV genome. Analysis of 75 serum samples from patients with chronic infection showed that HBV RNA levels were higher in core than in S and X regions (median 7.20 vs. 6.80 and 6.58 log copies/mL; p < .0001), whereas HBV DNA levels showed an inverse gradient (...

Hepatitis B virus (HBV) core protein-targeting compounds are in or entering clinical development without a standardized nomenclature. We propose a naming convention for these core-targeting antiviral products to provide clarity and accelerate HBV drug development.

Parvoviruses are small non‐enveloped single‐stranded DNA viruses, which depend on host cell nuclear transcriptional and replication machinery. After endosomal exposure of nuclear localization sequence and a phospholipase A2 domain on the capsid surface, and escape into the cytosol, parvovirus capsids enter the nucleus. Due to the small capsid diame...

Hepatitis B virus infections are the main reason for hepatocellular carcinoma development. Current treatment reduces the viral load but rarely leads to virus elimination. Despite its medical importance, little is known about infection dynamics on the cellular level not at least due to technical obstacles. Regardless of infections leading to extreme...

Significance Viral RNA may be edited by enzymes of the ADAR family that deaminate adenosine residues with ensuing A→G mutations. We found multiple A→G mutations in minor viral populations of the SARS-CoV-2 genome. A→G mutations accumulated in the receptor binding domain of the spike gene, which may cause structural changes by altering binding to th...

Parvoviruses are small single-stranded (ss) DNA viruses, which replicate in the nucleoplasm and affect both the structure and function of the nucleus. The nuclear stage of the parvovirus life cycle starts at the nuclear entry of incoming capsids and culminates in the successful passage of progeny capsids out of the nucleus. In this review, we will...

The family Hepadnaviridae comprises small enveloped viruses with a partially double-stranded DNA genome of 3.0-3.4 kb. All family members express three sets of proteins (preC/C, polymerase and preS/S) and replication involves reverse transcription within nucleocapsids in the cytoplasm of hepatocytes. Hepadnaviruses are hepatotropic and infections m...

Parvoviruses are an important platform for gene and cancer therapy. Their cell entry and the following steps including nuclear import are inefficient limiting their use in therapeutic applications. Two models exist on parvoviral nuclear entry: classical import of the viral capsid using nuclear transport receptors of the importin (karyopherin) famil...

Parvoviral genome translocation from the plasma membrane into the nucleus is a coordinated multistep process mediated by capsid proteins. We used fast confocal microscopy line scan imaging combined with image correlation methods including auto-, pair- and cross-correlation, and number and brightness analysis, to study the parvovirus entry pathway a...

The early steps of HBV entry remain largely unknown despite the recent discovery of an HBV-specific entry receptor. Following entry HBV capsids have to be transported through the cytoplasm to the nuclear periphery, followed by nuclear entry. These steps have to take place in a coordinated manner to allow delivery of the genome into the nucleus. Due...

Background & aims: Hepatitis B virus (HBV) has a DNA genome but replicates within nucleus by transcription of an RNA pregenome, which is converted to DNA in cytoplasmic capsids. Capsids in this compartment are correlated with inflammation and epitopes of the capsid protein core (Cp) are the main target for T cell-mediated immune response. We inves...

Protoparvoviruses target the nucleus due to their dependence on the cellular reproduction machinery during the replication and expression of their single-stranded DNA genome. In recent years, our understanding of the multistep process of the capsid nuclear import has improved, and led to the discovery of unique viral nuclear entry strategies. Prece...

Hepatitis B virus (HBV) is an enveloped pararetrovirus with a DNA genome, which is found in an up to 36 nm-measuring capsid. Replication of the genome occurs via an RNA intermediate, which is synthesized in the nucleus. The virus must have thus ways of transporting its DNA genome into this compartment. This review summarizes the data on hepatitis B...

Hepatitis B virus (HBV) capsids are found in many forms: immature single-stranded RNA-filled cores, single-stranded DNA-filled replication intermediates, mature cores with relaxed circular double-stranded DNA, and empty capsids. A capsid, the protein shell of the core, is a complex of 240 copies of core protein. Mature cores are transported to the...

Fitting an atomic model of Impβ into cryo-EM density. (a) The difference map of Impβ (red) was calculated by subtracting P-Cp183 capsid (Fig 3D) from P-Cp183-Impβ complex (Fig 3E). Prior to the subtraction, the sizes of these two maps were scaled and the density corresponding to the capsid shell region was normalized. The resulting Impβ density (re...

Estimated Impβ: Capsid ratio determined from size exclusion chromatography. As SEC is not an equilibrium technique, Impβ can dissociate during the course of the 40 minute-long experiment. In addition, some capsid-Impβ complex may precipitate before or during chromatography. These complications result in an underestimate of capsid-bound Impβ. (PDF)

Reference-free 2D classification of Cp183-Impβ in 0.15 M ammonium formate. Samples of high Impβ:capsid complexes (11 μM Cp183 dimer with 18.8 μM Impβ) were examined by cryo-EM. Unbiased 2D classification using RELION [84] showed three types: (i) T = 4 Cp183-Impβ particles, (ii) T = 4 Cp183-Impβ particles with dark interior, an additional ring-like...

Coomassie stained SDS-PAGE of Impβ. (PDF)

ESI mass spectra phosphorylated Cp183, P-Cp183, prepared by co-expression of Cp183 and SRPK (a) in capsids incorporating E. Coli RNA and (b) in empty capsids from purified P-Cp183. The peak labels show assignment, mass, and intensity. (PDF)

Fitting atomic models into cryo-EM of the Cp183/Impβ complex (upper panel). The atomic model of HBV (PDB code 1QGT, color in red, green, cyan and yellow) was fitted into cryo-EM density of Cp183/Impβ complex prepared in 0.15M ammonium formate. The left half of each panel shows the 3D reconstruction computed from whole particles and the right half s...

Data collection information. Data are presented for seven reconstructions of the full-length core protein Cp183 with and without Impβ. (PDF)

Resolution estimation. The black (phosphorylated empty Cp183), green (phosphorylated Cp183 with Impβ) and red (Cp183 with Impβ) curves show the FSC for the 3D reconstructions in Fig 3. The blue curves (thick, all particles; thin, dark particles) show the FSC for the 3D reconstruction in Fig 7. The gray curves (thick, all particles; thin, dark parti...

With about 350 million people chronically infected around the world hepatitis B is a major health problem. Template for progeny HBV synthesis is the viral genome, organized as a minichromosome (cccDNA) inside the hepatocyte nucleus. How viral cccDNA gene expression is regulated by its chromatin structure; more importantly, how the modulation of thi...

Hepatitis B virus (HBV) replicates its genomic information in the nucleus via transcription and therefore has to deliver its partially double stranded DNA genome into the nucleus. Like other viruses with a nuclear replication phase, HBV genomes are transported inside the viral capsids first through the cytoplasm towards the nuclear envelope. Follow...

The application of fluorescent proteins as expression markers and protein fusion partners has proved immensely valuable for resolving the organization of biological events in living cells. EGFP and DsRed2 are commonly fluorescent marker protein which is used for biotechnology and cell biology research. The present study was designed to identify the...

Background: This study was undertaken to determine the temporal relationship between implementation of different interventions in an intensive care unit (ICU) and control of endemic nosocomial acquisition of extended-spectrum β-lactamase Enterobacteriaceae (ESBLE). Methods: This was a prospective observational study with time-series analysis of...

It is unknown whether the mammalian cell cycle could impact the assembly of viruses maturing in the nucleus. We addressed this question using MVM, a reference member of the icosahedral ssDNA nuclear parvoviruses, which requires cell proliferation to infect by mechanisms partly understood. Constitutively expressed MVM capsid subunits (VPs) accumulat...

Les entérobactéries productrices de β-lactamases à spectre étendu (E-BLSE) sont responsables d’infections dont le traitement repose essentiellement sur les carbapénèmes. Leur caractère pandémique a eu pour conséquence une forte consommation de cette classe de β-lactamines. Au même moment ont émergé les carbapénémases. Ainsi, d’autres stratégies thé...

L’administration des aminoglycosides (AG) chez les patients en choc septique doit respecter une haute dose unique quotidienne (7–9 mg/kg de gentamicine/tobramycine et 25–30 mg/kg d’amikacine) en perfusion de 30 minutes et pour une durée <5 jours. Le poids réel actuel est utilisé, sauf chez les obèses. Leur administration n’est pas aisée chez les pa...

HBV infection is a major cause of liver cirrhosis and hepatocellular carcinoma. Although HBV infection can be efficiently prevented by vaccination, and treatments are available, to date there is no reliable cure for the >240 million individuals that are chronically infected worldwide. Current treatments can only achieve viral suppression, and lifel...

Unlabelled: In this study, we characterized the molecular basis for binding of adenovirus (AdV) to the cytoplasmic face of the nuclear pore complex (NPC), a key step during delivery of the viral genome into the nucleus. We used RNA interference (RNAi) to deplete cells of either Nup214 or Nup358, the two major Phe-Gly (FG) repeat nucleoporins local...

Background: The risk of cross-infection from shared ultrasound probes in endorectal and vaginal ultrasonography due to low-level disinfection (LLD) is difficult to estimate because potential infections are also sexually transmitted diseases, and route of contamination is often difficult to establish. In France, the widely used standard for prevent...

Patients' biopsies show that hepadnaviral core proteins and capsids - collectively called core - are found in the nucleus and in the cytoplasm of infected hepatocytes. In the majority of studies, cytoplasmic core localization is related to low viremia while nuclear core is associated with high viral load. In order to better understand the molecular...

Author Summary Certain human papillomaviruses (HPV) are the etiological cause of cervical cancers and other epithelial tumors. Recent advances in the development of anti-HPV vaccines and their increasing deployment provide hope for a significant decrease of these cancers in the future. However, many details of the transmission of HPV between infect...

In many countries, Low Level Disinfection (LLD) of covered transvaginal ultrasound probes is recommended between patients' examinations. The aim of this study was to evaluate the antimicrobial efficacy of LLD under routine conditions on a range of microorganisms. Samples were taken over a six month period in a private French Radiology Center. 300 s...

Disassembly of the nuclear lamina is essential in mitosis and apoptosis requiring multiple coordinated enzymatic activities in nucleus and cytoplasm. Activation and coordination of the different activities is poorly understood and moreover complicated as some factors translocate between cytoplasm and nucleus in preparatory phases. Here we used the...

Background: Telaprevir (TVR) is a protease inhibitor (PI) used in chronic hepatitis C treatment with pegylated interferon plus ribavirin. We analysed the prevalence and kinetic development of TVR resistance upon treatment. Methods: A total of 24 cirrhotic patients (genotype 1a, n=8; genotype 1b, n=16) previously non-responders to standard therap...

Cationic cell-penetrating peptides (CPPs) and their lipid domain-conjugates (CatLip) are agents for the delivery of (uncharged) biologically active molecules into the cell. Using infection and transfection assays we surprisingly discovered that CatLip peptides were able to inhibit replication of Duck Hepatitis B Virus (DHBV), a reference model for...

Effect on hepadnaviral release of (Arg)8 and Decanoic acid treatment in different cell culture systems. DHBV infected PDH (A); stably DHBV-transfected LMH-D2 (B) were treated with different amounts of (Arg)8 and decanoic acid ranking from 0. 5 µM to 10 µM in duplicates for 6 and 4 days respectively. Cell culture supernatants were collected daily du...

Dose dependent inhibition of hepadnaviral release by Deca-(Arg)8 in HBV-transfected HepG2.2.15. Stably HBV-transfected HepG2.2.15 cells were treated with different amounts of Deca-(Arg)8 ranking from 0.5 µM to 4 µM in duplicates for 5 days. Cell culture supernatants were collected daily during treatment. The kinetics of viral release in cell cultur...

Capsid protein of hepatitis B virus (HBV) consists of a single karyophilic protein species. It mediates the entry of the viral DNA into the nucleus using the cellular transport receptors importin α and ß. The nuclear localization signal (NLS) is localized within the C-terminus of the HBV capsid protein, overlapping with eight phosphorylation sites....

Adeno-associated virus type 2 (AAV2) has gained much interest as a gene delivery vector. A hallmark of AAV2-mediated gene transfer is an intracellular conformational change of the virus capsid, leading to the exposure of infection-relevant protein domains. These protein domains, which are located on the N-terminal portion of the structural proteins...

Every year, one million people dies from Hepatitis B virus. As for other viruses, its genetic material is enclosed by a capsid whose segmentation and classification is essential. In this paper, we present a novel capsid segmentation technique which is a combination of a “à trous” wavelet process (for background filtering) and a graph-based structur...

Bayer 41-4109 is heteroarylpyrimidine (HAP) which has been identified as potent of HBV capsid assembly inhibitor. The present study was to study effect of Bayer 41-4109 treatment on the intracellular localization of EGFP-Core fusion proteins into HepG2 cells. Three recombinant plasmids of pEGFP-Core with single, double and triple NLS of HBV core (E...

Capsids of hepatitis B virus and other hepadnaviruses contain a cellular protein kinase, which phosphorylates the capsid protein. Some phosphorylation sites are shown to be essential for distinct steps of viral replication as pregenome packaging or plus strand DNA synthesis. Although different protein kinases have been reported to phosphorylate the...

Virtually all DNA viruses including hepatitis B viruses (HBV) replicate their genome inside the nucleus. In non-dividing cells, the genome has to pass through the nuclear pore complexes (NPCs) by the aid of nuclear transport receptors as e.g. importin beta (karyopherin). Most viruses release their genome in the cytoplasm or at the cytosolic face of...

The central role of Raf protein kinase isoforms in human cancer demands specific anti-Raf therapeutic inhibitors. Parvoviruses are currently used in experimental cancer therapy due to their natural oncotropism and lytic life cycle. In searching for mechanisms underlying parvovirus oncolysis, we found that trimers of the major structural protein (VP...

Core protein of Hepatitis B virus (HBV) play an important role in infection of HBV into the liver cells. Core protein is also including in the HBV genome targeting into the nucleus through modulating carboxyl residues by phosphorylation. Nuclear localication Signal (NLS) in HBV core protein is inside the virion structure and it must be unmasked in...

: Complex retroviruses, retroelements and their hosts Meet ing abstracts - A single PDF containing all abstracts in this Supplement is available here . http://www. biomedcentral.co m/content/pdf/17 42-4690-6-S2-inf o.pdf

Assembly and disassembly of viral capsids are essential steps in the viral life cycle. Studies on their kinetics are mostly performed in vitro, allowing application of biochemical, biophysical and visualizing techniques. In vivo kinetics are poorly understood and the transferability of the in vitro models to the cellular environment remains specula...

Core antigen (HBcAg) is the most immunogenic component of hepatitis B virus (HBV) and is believed to induce virtually always antibodies (anti-HBc) in immunocompetent infected persons. However, some chronically infected persons do not develop detectable anti-HBc. A more sensitive assay for anti-HBc was to be developed and used to re-evaluate a cohor...

Sophisticated evasion strategies of obligate intracellular parasites, in particular prevention of host cell apoptosis, are necessary to ensure successful replication. To study the ability of Eimeria bovis in this regard, in vitro experiments were performed applying bovine foetal gastrointestinal cells (BFGC), bovine umbilical vein endothelial cells...

Biology of HepadnaviridaeStructure of HepadnaviridaeProtein composition of HBV particlesGenome of HBVHBs proteinsCore proteinsProducts of ORF PHBx proteinReplication of HBV

These assays and biochemical analyses have been used to analyse the nuclear import of the hepadnaviral genome in more detail. Using permeabilized cells it was shown that the HBV capsid protein contains an NLS within its C-terminal domain. This domain is hidden in the lumen of RNA-containing capsids expressed in E. coli and in eukaryotically express...

The biogenesis of spliceosomal small nuclear RNAs (snRNAs) involves organized translocations between the cytoplasm and certain nuclear domains, such as Cajal bodies and nucleoli. Here we identify human RBM28 protein as a novel snRNP component, based on affinity selection of U6 small nuclear ribonucleoprotein (snRNP). As shown by immunofluorescence,...

The hepatitis B virus (HBV) is an enveloped DNA virus which is highly infectious in vivo. In vitro, only primary hepatocytes of humans and Tupaia belangeri or the novel HepaRG cell line are susceptible to HBV, but infection is inefficient and study of early infection events in single cells is unsatisfactory. Since hepatoma cells replicate the virus...

APOBEC3G is a cellular cytidine deaminase displaying broad antiretroviral activity. Recently, it was shown that APOBEC3G can also suppress hepatitis B virus (HBV) production in human hepatoma cells. In the present study, we characterized the mechanisms of APOBEC-mediated antiviral activity against HBV and related hepadnaviruses. We show that human...

Chronic hepatitis B virus (HBV) infection is a major cause of liver disease. Only interferon-alpha and the nucleosidic inhibitors of the viral polymerase, 3TC and adefovir, are approved for therapy. However, these therapies are limited by the side effects of interferon and the substantial resistance of the virus to nucleosidic inhibitors. Potent ne...

Eukaryotic cells are compartmentalized and therefore possess mechanisms to transport molecules between the different organelles. Viruses take advantage of cellular transcription and translation machinery for their multiplication. Consequently, they utilize cellular routes for transporting their proteins and genome into the correct compartments.

A major issue of current virology concerns the characterization of cellular proteins that operate as functional components of the viral multiplication process. Here we describe a group of host factors designated as 'NFAR proteins' that are recruited by the replication machinery of bovine viral diarrhea virus, a close relative of the human pathogen...

While studying the import of the hepatitis B virus genome into the nucleus of permeabilized tissue culture cells, we found that viral capsids were imported in intact form through the nuclear pore into the nuclear basket. Import depended on phosphorylation of the capsid protein and was mediated by the cellular transport receptors importin alpha and...

Viral nucleocapsids compartmentalize and protect viral genomes during assembly while they mediate targeted genome release during viral infection. This dual role of the capsid in the viral life cycle must be tightly regulated to ensure efficient virus spread. Here, we used the duck hepatitis B virus (DHBV) infection model to analyze the effects of c...

The open reading frame UL84 of human cytomegalovirus encodes a multifunctional regulatory protein which is required for viral DNA replication and binds with high affinity to the immediate-early transactivator IE2-p86. Although the exact role of pUL84 in DNA replication is unknown, the nuclear localization of this protein is a prerequisite for this...

We report here a partial characterization of a "tet-on" glia O2A precursor cell line established from the reverse tetracycline-transactivator (rtTA)-SV40 T antigen (Tag) double transgenic mice. In culture, withdrawal of doxycycline prevents proliferation and the cell line undergoes apoptosis. Importantly, differentiation into type-2-astrocytes and...

Nuclear import of many cellular and viral proteins is mediated by short nuclear localization signals (NLS) that are recognized by intracellular receptor proteins belonging to the importin/karyopherin α and β families. The primary structure of NLS is not well defined, but most contain at least three basic amino acids and harbor the relative consensu...

Bidirectional transport of macromolecules between the nucleus and the cytoplasm occurs through the nuclear pore complexes (NPCs) by a signal-mediated mechanism that is directed by targeting signals (NLSs) residing on the transported molecules or "cargoes." Nuclear transport starts after interaction of the targeting signal with soluble cellular rece...

Stem cells, having the property of self renewal, offer the promise of lifelong repair of damaged tissue. However, somatic tissue-committed primary stem cells are rare and difficult to expand in vitro. Genetically modified stem-like cells with the ability to expand conditionally provide a valuable tool with which to study stem cell biology, especial...

Because many viruses replicate in the nucleus of their host cells, they must have ways of transporting their genome and other components into and out of this compartment. For the incoming virus particle, nuclear entry is often one of the final steps in a complex transport and uncoating program. Typically, it involves recognition by importins (karyo...

Although many viruses replicate in the nucleus, little is known about the processes involved in the nuclear import of viral genomes. We show here that in vitro generated core particles of human hepatitis B virus bind to nuclear pore complexes (NPCs) in digitonin-permeabilized mammalian cells. This only occurred if the cores contained phosphorylated...

The modular architecture of the nuclear pore complex (NPC) consists of a membrane‐embedded basic framework (the ‘spoke complex’) made up of eight multidomain spokes with two rings on each face (Figure 1A). The ring facing the cytoplasm is decorated with eight ∼50 nm fibrils extending into the cytosol, and the nuclear ring is capped with a basket‐li...

Hepatitis B virus (HBV) has been reported to exist in peripheral blood mononuclear cells (PBMC), but it is not clear whether it replicates there. A precondition for replication should be the formation of covalently closed viral DNA and transcription of all essential viral mRNAs. The mRNAs of HBV form a nested box with common 3' ends. In order to de...

Hepadnaviruses contain a DNA genome, but they replicate via an RNA intermediate, synthesized by the cellular RNA polymerase II in the nucleus of the infected cell. Thus, nuclear transport of the viral DNA is required in the viral life cycle. Protein-free DNA is only poorly imported into the nucleus, so one or more of the viral proteins must be invo...

We have developed a sensitive and quantitative assay for hepatitis B virus (HBV) DNA in serum or plasma in which PCR and then microtiter hybridization analysis are used. Assay of HBV DNA in serum or plasma is important for demonstrating viral replication, indicating and monitoring antiviral therapy, determining the infectivities of virus carriers,...

Recent results are reviewed on the role of the HBx protein in virion production, the significance of phosphorylation in core protein for RNA encapsidation, intracellular transport of the HBV genome, the morphogenesis of virions, and the early stages of infection in cell cultures.

Phosphorylation of core particles derived either from hepatitis B viruses or from livers of hepatitis B-infected individuals has been long recognized, but the nature and function of the phosphorylating enzyme remained unknown. By immunoblotting with a monoclonal antibody, we have now detected protein kinase C within the liver-derived core particles...

The prevalence and time course of the occurrence of antibodies to the hepatitis B virus polymerase (anti-HBpol) were investigated in acutely and in chronically HBV-infected individuals by using recombinant HBpol protein for Western blot analysis. One group consisted of 19 patients who were acutely infected and recovered completely. Five of these pa...

In the University Hospital in Gottingen, the spectra of fungal species in clinical specimens of respiratory secretions, bronchial secretions and urine were compared over periods of 15 months (10/87 to 12/88 and 1/91 to 3/92) before and after the introduction of fluconazole. The following changes could be demonstrated: These changes in the spectra o...

During the assembly of the nucleocapsid of the hepatitis B virus a protein kinase, probably of cellular origin, is encapsidated. This enzyme phosphorylates serine residue(s) localized within the lumen of the particle. By using purified, liver-derived core particles, we characterized the protein kinase activity in the presence of different ions and...

The hepatitis B virus, although containing a DNA genome, replicates by reverse transcription of an RNA pregenome. The viral Pol gene encodes the reverse transcriptase which catalyzes viral DNA synthesis. To study the interaction of this protein with HBV RNA, the entire Pol gene product was expressed except its eight amino-terminal codons in Escheri...

We have studied the effect of acetazolamide 500 mg bd for three days on ventilatory response to CO2 (HCVR) and hypoxia under both isocapnic and poikilocapnic conditions (isocapnic and poikilocapnic HVR) in five normal subjects. Although acetazolamide reduced calculated arterial pH (7.41 [SEM] 0.01 to 7.37 [SEM] 0.01: p less than 0.01) there was no...