[Can the antibiotic prescription practice in a hospital be influenced by in-house guidelines? An interventional study at the University Hospital Halle (Saale), Germany]. / Lässt sich die Antibiotikaverordnungspraxis im Krankenhaus durch hausinterne Richtlinien beeinflussen? Interventionsstudie am Universitätsklinikum Halle (Saale).

BACKGROUND: In-house guidelines are an essential tool of antibiotic stewardship (ABS) programs to guide antimicrobial therapy. We studied the effect of in-house guidelines adapted to the local pathogen and resistance epidemiology on prescribing behavior. METHODS: At the University Hospital Halle (Saale) guidelines for the antimicrobial therapy and essential microbiological diagnostics were introduced. Main objectives were reducing the use of third generation cephalosporines and fluoroquinolones, decreasing selection pressure for enterococci and multidrug-resistant Gram-negative bacteria, minimizing Clostridium difficile infections (CDI), and improving microbiological diagnostics to enhance de-escalation strategies. 12 months thereafter a comparison of antibiotic consumption, pathogen and resistance statistics and use of blood cultures was performed. RESULTS: There was a decrease of third-generation cephalosporines (-18.6%) and fluoroquinolones (-9.8%), while consumption of broad- and intermediate-spectrum penicillins (+23.8% and +37%) as well as carbapenems (+11.9%) increased. The total volume of prescribed anti-infectives remained unchanged. The number of enterococcal isolates (-18.3%) and CDI (-26.3%) decreased considerably. Gram-negatives, particulary ESBL-producing Enterobacteriaceae, were detected more frequently due to an expanded screening program. The rate of blood cultures/1000 patient-days was unaffected. CONCLUSION: In-house guidelines for the empiric antiinfective therapy appear to be suitable to influence the prescribing behavior and the selection pressure on individual pathogen groups. The total volume of antibiotic prescriptions was not affected in this study.

Colonization and infection due to multi-resistant bacteria in neonates: a single center analysis.

BACKGROUND: In the last years the prevalence of multi-resistant pathogens (MRPs) has increased. Systemic infections remain important for neonatal morbidity and mortality. PATIENTS: Neonates born between January 2011 and December 2012 and admitted to the neonatology before their tenth day of life were included into this retrospective analysis. Vancomycin-resistant Enterococci, Methicillin-resistant Staphylococcus aureus, Gram-negative bacilli with Extend Spectrum Beta Lactamase or AMP-C resistance were defined as multi-resistant pathogens (MRPs). MRP positive and negative patients were analyzed regarding clinical risk factors and the incidence of systemic infections. RESULTS: 635 neonates were admitted during the analysis period. In 31 patients MRPs were detected. 2 patients developed MRP-associated infections. Both were discharged without long term health risks. Low gestational age and need for mechanical ventilation were risk factors for colonization with MRPs in the univariat analysis. The incidence density (per 1 000 patient days) for all MRE increased from 0.76 in 2011 to 3.51 in 2012. In contrast the sepsis rate remained stable (14.9% and 14.2%). 2 MRP colonization clusters were detected by routine microbiology swabs. Both could be controlled by appropriate hygienic measures. CONCLUSIONS: The prevalence of Gram-negative MRPs increased in neonates. Microbiological screening seems to be helpful for early detection of colonization and thus prevention of nosocomial infections with MRPs. Despite the increased attention towards the problems associated with multiresistant bacteria, there are still major efforts needed for prevention and early treatment of sepsis with non-resistant bacteria.

[Immunosuppressive treatment as a risk factor for the occurrence of clostridium difficile infection (CDI)]. / Immunsuppressive Behandlung als Risikofaktor für das Auftreten einer Clostridium-difficile-Infektion (CDI).

BACKGROUND: Toxigenic Clostridium difficile strains are known as the most common infectious cause of antibiotic-associated intestinal disease and nosocomial diarrhoea. The increased incidence of hypervirulent strains gives rise to worldwide concern. In particular, courses with multiple recurrences are observed in the presence of immunosuppression. METHODS: In this retrospective controlled observational study we aimed to determine immunosuppression as an independent risk factor for symptomatic CDI and to identify characteristics and differences of immunocompromised patients with respect to disease severity, disease progression, intestinal manifestations, recurrence rates and other factors. We compared symptoms and clinical features of 55 immunosuppressed patients with confirmed CDI with those of 50 patients without immunosuppressive medication (mean age 59.3 years ±â€Š16.2 vs. 69.2 years ±â€Š15.0) who were treated at the Departments of Internal Medicine I and IV of the University Hospital Halle (Saale), Germany, between 2006 and 2009. Multivariate analysis using binary logistic regression was performed for a control group of 105 patients without CDI. In this group, there were 62 patients without evidence of immunosuppression and 43 immunosuppressed patients (mean age 66.9 years ±â€Š12.4 vs. 56.0 years ±â€Š13.7). RESULTS: The clinical courses of the two groups differed considerably. Immunosuppressed patients were significantly more frequently colonised with Clostridium difficile without clinically detectable manifestation or only mild clinical symptoms not requiring therapy (22 vs. 2 %, p = 0.003), while there were similar numbers of moderate (46 vs. 52 %, p = 0.503) but less severe CDI cases (27 vs. 40 %, p = 0.167). Relapses were observed more frequently in the group of immunosuppressed patients (15 vs. 6 %, p = 0.153). Multivariate analysis using logistic regression identified immunosuppression as an independent risk factor for CDI (OR = 2.75), in addition to prior antibiotic therapy (OR = 10.15) and PPI intake (OR = 2.93). CONCLUSION: We conclude that immunosuppression has to be regarded as an independent risk factor for CDI. Immunosuppressive treatment increases the risk of colonisation and infection with Clostridium difficile and leads to a higher relapse rate in patients with CDI.

[Results of surveillance cultures on a neonatal intensive care unit: a retrospective analysis]. / Ergebnisse des mikrobiologischen Screenings auf einer neonatologischen Intensivstation: Retrospektive Analyse.

BACKGROUND: Microbiological screening (MS) is standard on neonatal intensive care units (NICU). Objectives are the collection of information regarding bacterial pathogens of the individual patient as well as of the NICU, especially of multidrug-resistant pathogens (MRE). The role of microbiological screening for preterm infants ≤32 weeks of gestational age has not been fully evaluated. PATIENTS AND METHODS: For preterm infants ≤32 weeks of gestational age admitted during a 41-month period the results of microbiological screening during the first 2 weeks of life were analysed retrospectively. The results were associated with documented septic episodes. RESULTS: Bacteria were isolated in 215/972 of postnatal and 416/862 of later swabs. Detection of bacteria in the initial MS was associated with vaginal birth, low gestational age, low APGAR values at 5 and 10 min and mechanical ventilation. The proportion of patients with positive microbiological screening in subsequent swabs was not influenced by gestational age, birth weight, sex, mode of delivery and APGAR score. During the observation period 52 cases of sepsis (28 clinic, 24 microbiological) occurred. The sepsis rate was increased in patients with positive postnatal swabs, low gestational age, low birth weight, low 5 min APGAR score, male sex or need for mechanical ventilation. CONCLUSIONS: Microbiological screening provides an overview of the NICU-specific pathogens but is of limited value in the prediction of septicaemias in preterm infants ≤32 weeks gestational age.

Microbial diagnostics in patients with presumed severe infection in the emergency department.

INTRODUCTION: Sepsis in the early stage is a common disease in emergency medicine, and rapid diagnosis is essential. Our aim was to compare pathogen diagnosis using blood cultures (BC) and the multiplex polymerase chain reaction (PCR) test.Methods. At total of 211 patients admitted to the multidisciplinary emergency department of our university hospital between 2006 and 2009 with suspected severe infection from any origin were studied. Blood samples for BC (aerobic and anaerobic) and multiplex PCR were taken for identification of infectious microorganisms immediately after hospital admission. Results of the BC and PCR correlated with procalcitonin concentration (PCT) and clinical diagnosis of sepsis (≥2 positive SIRS criteria) as well as with severity of disease at admission and with clinical outcome measures. RESULTS: Results of the BC were available in 200 patients (94.8%) and PCR were available in 119 patients (56.3%), respectively. In total, 87 BC (43.5%) were positive and identified 94 pathogens. In 45 positive PCRs, 47 pathogens (37.8%) were found. Identical results were obtained in 81.4%. In addition, BC identified 9 Gram-positive and 3 Gram-negative bacteria, while PCR added 5 Gram-negative pathogens. Coagulase-negative staphylococci were detected in blood cultures only (n=20, 21.3%), whereas PCR identified significantly more Gram-negative bacteria than BC. In patients with positive PCR results, the PCT level was significantly higher than in patients with negative PCR (15.0±23.3 vs. 8.8±32.8 ng/ml, p<0.001). This difference was not observed for BC (10.6±25.7 vs. 11.6±44.9 ng/ml, p=0.075). The APACHE II score correlated with PCR (19.2±9.1 vs. 15.8±8.9, p<0.05) and was also higher in positive BC (18.7±8.7 vs. 14.4±8.0, p<0.01). Positive PCR and BC were correlated with negative clinical outcomes (e.g., transfer to ICU, mechanical ventilation, renal replacement therapy, death). CONCLUSION: In patients admitted with suspected severe infection, a high percentage of positive BC and PCR were observed. Positive findings in the PCR correlate with elevated levels of PCT and high APACHE II scores.

[Unexplained fever and B-symptoms in a young male Black African]. / Unklares Fieber und B-Symptome bei einem jungen Schwarzafrikaner.

An immunocompetent Nigerian developed a fulminant hemophagocytic lymphohistiocytosis due to Epstein-Barr virus reactivation. The patient initially presented with fever, hepatosplenomegaly and pancytopenia. The clinical status of our patient deteriorated quickly despite treatment with corticoids. Escalation of immunosuppressive treatment was not possible. He died of lung, liver and circulatory failure in our intensive care unit.Hemophagocytic lymphohistiocytosis is a rare disease characterized by inflammation due to prolonged and excessive activation of antigen-presenting cells. High plasma ferritin levels and phagocytosis of hematopoetic cells in bone marrow, spleen and liver lead to the diagnosis. Hemophagocytic lymphohistiocytosis should therefore be included in the differential diagnosis in patients with persistent fever, hepatosplenomegaly and cytopenia.

[37-year old patient with fever, diarrhea and lymphadenopathy]. / 37-jähriger Patient mit Fieber, Durchfall und Lymphknotenschwellung.

A 37-year-old homosexual man was admitted because of oropharyngeal pain, fever, diarrhea, loss of weight and lymphadenopathy since one week. Acute retroviral syndrome (ARS) in primary HIV type 1 infection was diagnosed, associated with Giardia lamblia infection. Antiinfective and combined antiretroviral treatment was established, and the general condition of the patient rapidly improved. The presented report demonstrates that in case of acute HIV-infection with diarrhea other infections should be considered, particularly with regard to enteropathogens like Giardia lamblia.

In vitro activity of linezolid against clinical isolates of Fusobacterium spp.

OBJECTIVES: Although most susceptibility studies for linezolid have investigated aerobic bacteria, only a few have investigated anaerobe isolates. The aim of the present study was to determine the antibacterial activity of linezolid against a larger sample of clinical isolates of Fusobacterium spp. and to report on the detailed susceptibility, stratified by species. METHODS: The in vitro susceptibility of 80 clinical isolates of Fusobacterium (Fusobacterium necrophorum, n = 34; Fusobacterium nucleatum, n = 20; Fusobacterium varium, n = 18; Fusobacterium mortiferum; n = 8) was tested and compared with the activity of the older compounds amoxicillin and amoxicillin/clavulanic acid. RESULTS: The MIC of linezolid ranged from 0.016 to 1.0 mg/L, with the MIC(90) being 0.5 mg/L. The highest MIC obtained for linezolid (1.0 mg/L) was measured for an F. varium isolate. The MIC(90) for both, amoxicillin (range: 0.016-0.75 mg/L) and amoxicillin/clavulanic acid (range: 0.047-0.75 mg/L), was 0.5 mg/L. Overall, no resistant strains were found in the study. CONCLUSIONS: Compared with amoxicillin and amoxicillin/clavulanic acid, linezolid was less active against F. necrophorum (MIC(90) 0.25 mg/L) and F. nucleatum (MIC(90) 0.25 mg/L), equally active against F. varium (MIC(90) 0.75 mg/L) and slightly more active against F. mortiferum (MIC(90) 0.19 mg/L).

Identification of a novel sequence at the 3' end of the GB virus B genome.

GB virus B (GBV-B) is a virus of the family Flaviviridae that infects small primates (Saguinus sp. [tamarins]) and shows similarities to hepatitis C virus (HCV) in genome organization, protein function, tissue tropism, and pathogenicity. This suggests the possibility of using tamarins infected by GBV-B or GBV-B/HCV chimeric viruses as a surrogate animal model of HCV infection. To achieve the construction of such chimeric viruses, it is essential to produce a complete and infectious GBV-B genomic RNA. We have identified a novel sequence at the 3' end of the GBV-B genome and show that it can be arranged in a secondary structure resembling that of the 3' end of the HCV genome, which is known to be essential for infectivity.

Quality control study on the performance of GB virus C/hepatitis G virus PCR.

BACKGROUND/AIMS: A novel virus, GBV-C/HGV, with a genome RNA organization similar to that of the Flaviviridae family was identified in sera of patients with hepatitis. The presence of GBV-C/HGV RNA can only be determined by the amplification of genomic regions using the reverse transcriptase-polymerase chain reaction (RT-PCR). METHODS: To assess the quality of the RT-PCR, 14 laboratories investigated a coded serum panel that comprised three GBV-C/HGV RNA-positive sera from three different patients, dilutions of these sera, and three GBV-C/HGV RNA-negative serum samples, two of which were collected from patients with hepatitis C but without GBV-C/HGV infection. In-house RT-PCR as well as commercially available GBV-C/HGV test kits were used in this study. RESULTS: Only four laboratories (29%) reported the expected results, and four laboratories (29%) false-positive results; nine laboratories (64%) reported at least one false-negative result. Eleven laboratories (79%) detected the undiluted samples. The majority of false results were obtained with the dilutions of GBV-C/HGV RNA-positive samples. Negative results in the 10(-4) dilution were not considered to be false-negative, since during pre-screening GBV-C/HGV RNA had been detected in this dilution in only 50% of assays by the three laboratories involved in organizing the evaluation. Results obtained by commercial kits and by in-house assays were indiscriminate in quality of performance in this study. CONCLUSION: To facilitate further quality assessment studies on the performance of GBV-C/HGV RNA detection, an international GBV-C/HGV RNA standard should be made available. Further efforts are required to optimize GBV-C/HGV RT-PCR.

Isolation and molecular characterization of hepatitis B virus X-protein from a baculovirus expression system.

The X protein (HBx) of the human Hepatitis B Virus (HBV) is a regulatory protein that exercises a transcriptional activator function on a variety of regulatory elements and is therefore considered to be involved in the development of human hepatocellular carcinoma (HCC). So far, most attempts at elucidating HBx function have been undertaken at the genetic level, reflecting the difficulties in detecting the very low amounts of the protein in infected livers. Consequently, the questions of intracellular localization and posttranslational modification have not yet been completely answered. We therefore constructed recombinant baculoviruses that allowed expression of HBx and the hexa histidine HBx fusion protein HBxHis in insect cells. Cell fractionation experiments revealed that only a minor part of HBx is detectable in a soluble form in the cytosolic fraction, whereas most of the protein forms intracellular aggregates. These results could be confirmed by confocal laser immunofluorescence. The fusion of a hexa-histidine tag to the amino terminus of HBx allowed a rapid one-step purification by metal chelate affinity chromatography. The detailed analysis of purified HBxHis using electrospray ionization mass spectrometry uncovered two major components: the unmodified, monomeric, fully oxidized form with five intramolecular disulfide bridges, and its N-acetylated modification. Additionally, two minor peaks with mass differences of delta m = +80 da suggested that a small fraction of HBx becomes posttranslationally phosphorylated in insect cells. No further modifications could be observed, indicating that only phosphorylation might play a role in a possible posttranslational regulation of this viral activator.

Hepatoma-derived integrated HBV DNA causes multi-stage transformation in vitro.

The hepatoma-derived hepatitis B virus (HBV) DNA insert HU-a has recently been shown to contain two viral transactivator genes, X and preS2 /S. We report here that HU-a induces malignant transformation after stable transfection of the fetal mouse hepatocyte line FMH202, as indicated by soft agar growth and nude mouse tumorigenicity. Transfections with HU-a subclones, containing the X gene of the preS2 /S gene alone or sequences without transactivator gene, respectively, suggested that the X gene is essential for transformation. Sequential stages of transformation and tumor progression were analysed by injection of the stably transfected FMH202 lines into nude mice, explanation of the resulting tumors and re-establishment of cell lines from the tumors. Comparison of two HU-a-transformed cell lines by HBV mRNA hybridization, Southern analysis and chromosomal in situ hybridization revealed that integrated HBV DNAs were involved in major chromosomal rearrangements in both cases. Interestingly, recombination of the HBV Dna insert during the nude mouse passage had completely abolished HBV-specific transcription in one case, indicating that expression of integrated HBV genes, while presumably involved in early transformation, is dispensable at later stages of tumor progression. The sequential transformation observed in this experimental system suggests that expression of the X gene by integrated viral DNA and subsequent hepatocyte genome mutations might both contribute to HBV-associated liver carcinogenesis.

The HBV-producing cell line HepG2-4A5: a new in vitro system for studying the regulation of HBV replication and for screening anti-hepatitis B virus drugs.

All tissue culture systems for propagating HBV employed so far make use of tandemly arranged HBV genomes usually under the control of strong foreign promoters. Thus these systems are helpful for virus production but are of limited value in the investigation of the regulation of HBV replication or of the extent to which the expression of viral genes might be influenced by cellular signal transduction pathways. To overcome this barrier we established an HBV-producing cell line (HepG2-4A5) by stably transfecting HepG2 cells with a replication-competent, terminally redundant HBV plasmid (pSPT1.2 xHBV) that contains each of the four major HBV-ORFs only once and exclusively under the control of their own regulatory elements. HepG2-4A5 cells contain a single, nonrearranged, chromosomally integrated, replication-competent HBV genome. In the cytoplasm of HepG2-4A5 cells, all typical viral mRNAs were detectable, but no other viral transcripts were found. Furthermore, all viral gene products are synthesized in a balanced ratio, as close as possible to that found in an in vivo infection. Dane-like particles released from HepG2-4A5 cells were indistinguishable from virions synthesized in vivo, by all physical (electron microscopy, buoyant density) and biochemical (endogenous polymerase reaction, immunogenic behaviour) criteria. Because of the autologous genome organization in this system, the HepG2-4A5 cell line allows studies on the function of the HBV gene products with respect to their involvement in regulating HBV replication under conditions imitating as closely as possible the situation in vivo. Furthermore, this cell line might be a helpful tool in screening antiviral drugs and in studying their effect on regulating HBV replication.

The hepatitis B virus preS2/St transactivator utilizes AP-1 and other transcription factors for transactivation.

Integrated hepatitis B virus DNA cloned from hepatitis B virus-associated hepatocellular carcinoma frequently contains 3'-truncated middle surface genes (preS2/St), which were recently found to have a transcriptional transactivator function. Because preS2/St, among others, is able to transactivate the promoters of the cellular oncogenes c-myc and c-fos, it has been speculated that integrated preS2/St genes might contribute to hepatitis B virus-associated liver carcinogenesis. In this study, we investigated the mechanism of target gene stimulation by preS2/St. It was found that deletion of a fragment containing the binding site for transcription factor AP-1 (Jun-Fos) substantially decreases inducibility of the human c-myc promoter by preS2/St. A subsequent investigation of AP-1 activation by preS2/St revealed the following: (a) insertion of multimeric AP-1 binding sites confers inducibility to an otherwise unstimulatable test promoter; (b) transactivation of AP-1 sites is dramatically increased when Jun and Fos are overexpressed by cotransfected expression plasmids; and (c) inhibitors of AP-1 activation also impair transactivation by preS2/St. Besides AP-1, preS2/St was also able to utilize the unrelated transcription factors NF-kappa B and AP-2 for transactivation, suggesting that the gene product of preS2/St acts indirectly through one or several general cellular pathways rather than as a bona fide transcription factor. Because AP-1 conveys induction of a large panel of tumor-relevant genes, its preS2/St-dependent activation implies a possible causative role in hepatitis B virus-associated hepatocarcinogenesis.

ER-localization and functional expression of the HBV transactivator MHBst.

In two recently reported cases, integrated hepatitis B virus (HBV) DNAs cloned from hepatocellular carcinoma were found to express a transcriptional transactivator from 3'-terminally truncated HBV surface (preS/S) genes. In this study, we characterized the transactivator at the protein level. Expression of a 3'-truncated preS2/S gene in Spodoptera frugiperda (Sf9) insect cells resulted in a C-terminally truncated middle surface protein of 76 amino acids (MHBst76), which was found to be associated with membranes of the endoplasmic reticulum and retained from Golgi processing and secretion. Accordingly, the microsome fraction of MHBst76-expressing Sf9 cells displayed transactivator activity after electric field-mediated transfer into Chang liver cells. In contrast to full-length MHBs, MHBst76 is unglycosylated, and glycosylation is not required for transactivation as shown by mutation of the glycosylation site at asparagine-4. Since highly purified MHBst76 derived from an E. coli expression system also showed transactivator activity, it is concluded that unglycosylated MHBst76 protein is the authentic transactivating factor. As the transactivator protein derives from inactive MHbs by rearrangements of integrated HBV DNA, it may be important for HBV-associated liver carcinogenesis.

The hepatitis B virus transactivator HBx causes elevation of diacylglycerol and activation of protein kinase C.

Chronic infection with hepatitis B virus (HBV) is accompanied by an increasing risk of developing hepatocellular carcinoma. There are indications that the HBx protein of HBV is involved in the process of tumour formation. HBx also transactivates several transcription factor binding sites. Recently, we reported that HBx can use a tumour promotor pathway for transactivation. In particular, we found that transactivation of the binding motif for transcription factor AP-1 (JUN/FOS) by HBx is dependent on functional protein kinase C (PKC), as indicated by abolition of the transcriptional stimulation following downregulation or inhibition of the enzyme. Moreover, HBx activates PKC, probably via increasing the endogenous PKC activator sn-1,2-diacylglycerol (DAG). Here we extend these data and report on the time course of PKC activation. We found that activation of PKC by HBx is transient and differs from activation of PKC by the ras oncogene product or phorbol ester in that it does not lead to rapid downregulation of the enzyme subsequent to the activation. Moreover, we provide evidence that an increase in cellular DAG is observable not only as an early event in response to HBx but also in cell lines transformed after transfection with HBV DNA and stably expressing HBx. Besides its important role in the regulation of cellular genes, PKC is also the intracellular receptor for tumour-promoting agents and an activator of proto-oncogenes, suggesting that our observations might provide an explanation for the oncogenic properties of HBx.

Hepatitis B virus transactivator HBx uses a tumour promoter signalling pathway.

The hepatitis B virus (HBV) transactivator protein HBx is enigmatic in that it stimulates a striking variety of promoters which do not share a common cis-regulatory element. As it does not bind to DNA, it has been speculated that HBx acts indirectly through cellular pathways. Under certain conditions HBx can have an oncogenic potential, which may be relevant for HBV-associated liver carcinogenesis, but until now the mechanism for transactivation and cell transformation by HBx was unclear. We report here that HBx uses a complex signal transduction pathway for transactivation. An increase in the endogenous protein kinase C (PKC) activator sn-1,2-diacylglycerol and the subsequent activation of PKC give rise to activation of the transcription factor AP-1 (Jun-Fos). As a result, HBx transactivates through binding sites for AP-1 and other PKC-dependent transcription factors (AP-2, NF-kappa B), thereby explaining the as-yet incomprehensible variety of HBx-inducible genes. As the PKC signal cascade also mediates cell transformation by tumour-promoting agents, the mechanism presented here might account for the oncogenic potential of HBx.

The hepatitis B virus pre-S/S(t) transactivator is generated by 3' truncations within a defined region of the S gene.

Recently, it was reported that 3' truncation of an integrated surface gene (pre-S2/S) cloned from a hepatitis B virus (HBV)-associated hepatoma gave rise to the generation of a C-terminally truncated middle surface protein (MHBst), which surprisingly exerted a transcriptional transactivator function. To define the molecular requirements for the generation of transactivating MHBs(t) proteins, a 3' deletion analysis of the HBV pre-S2/S gene was performed. In cotransfection experiments with reporter plasmid pSV2CAT, full-length pre-S2/S genes or pre-S2/S genes with minor 3'-terminal deletions did not exhibit transactivator activity. In contrast, deletion of C-terminal hydrophobic region III of the S domain generated the transactivator function. Further stepwise 3' deletions, removing hydrophobic region II and both hydrophilic regions of the S domain, did not interfere with the transactivator activity; it was completely abolished, however, after additional deletion of hydrophobic region I. The results of this study define a range within the S open reading frame (between HBV nucleotides 221 and 573), termed the trans-activity-on region, in which 3' deletions give rise to the generation of transactivating MHBs(t) proteins. Within this region, not only 3' deletions but also the introduction of a stop codon activated the transactivator function, indicating that point mutations of integrated HBV DNA also may give rise to the synthesis of transactivating MHBs(t) proteins in vivo.

Trans-activation by hepatitis B virus X protein is mediated via a tumour promoter pathway.

We have studied the c-myc gene as a possible target of HBV X protein in liver carcinogenesis. Our results indicate that trans-activation by X protein occurs via PKC/AP1 signal transduction, suggesting a possible two-step mechanism in HBV related liver carcinogenesis.