The Hepatitis B Virus Ribonuclease H Is Sensitive to Inhibitors of the Human Immunodeficiency Virus Ribonuclease H and Integrase Enzymes

Nucleos(t)ide analog therapy blocks DNA synthesis by the hepatitis B virus (HBV) reverse transcriptase and can control the infection, but treatment is life-long and has high costs and unpredictable long-term side effects. The profound suppression of HBV by the nucleos(t)ide analogs and their ability to cure some patients indicates that they can push HBV to the brink of extinction. Consequently, more patients could be cured by suppressing HBV replication further using a new drug in combination with the nucleos(t)ide analogs. The HBV ribonuclease H (RNAseH) is a logical drug target because it is the second of only two viral enzymes that are essential for viral replication, but it has not been exploited, primarily because it is very difficult to produce active enzyme. To address this difficulty, we expressed HBV genotype D and H RNAseHs in E. coli and enriched the enzymes by nickel-affinity chromatography. HBV RNAseH activity in the enriched lysates was characterized in preparation for drug screening. Twenty-one candidate HBV RNAseH inhibitors were identified using chemical structure-activity analyses based on inhibitors of the HIV RNAseH and integrase. Twelve anti-RNAseH and anti-integrase compounds inhibited the HBV RNAseH at 10 μM, the best compounds had low micromolar IC50 values against the RNAseH, and one compound inhibited HBV replication in tissue culture at 10 μM. Recombinant HBV genotype D RNAseH was more sensitive to inhibition than genotype H. This study demonstrates that recombinant HBV RNAseH suitable for low-throughput antiviral drug screening has been produced. The high percentage of compounds developed against the HIV RNAseH and integrase that were active against the HBV RNAseH indicates that the extensive drug design efforts against these HIV enzymes can guide anti-HBV RNAseH drug discovery. Finally, differential inhibition of HBV genotype D and H RNAseHs indicates that viral genetic variability will be a factor during drug development. © 2013 Tavis et al

Comparability of localization data in transnasal and transoral esophagogastroduodenoscopy

<p>Abstract</p> <p>Background</p> <p>Esophagogastroduodenoscopy is an often-used and safe diagnostic method in gastroenterology. Transnasal esophagogastroduodenoscopy is now an established addition to the endoscopic instrumentarium. Although the two examination methods can be used alongside each other, there is a lack of studies on the comparability of the localization data obtained with the transoral and transnasal methods.</p> <p>Methods</p> <p>In 135 adult patients presenting for routine outpatient esophagogastroduodenoscopy, transoral esophagogastroduodenoscopy (TOG) was carried out after transnasal esophagogastroduodenoscopy (TNG), and the distance from the naris or incisors, respectively, to the esophagogastric junction was measured.</p> <p>Results</p> <p>The data for 135 patients were analyzed. With the transoral access route, the distance from the upper incisors to the cardia was a mean of 40.5 cm (SD ± 3.4 cm). In the transnasal examinations, the mean distance between the naris and the cardia was 45.6 cm (SD ± 3.5 cm). The correlation analysis showed a very close correlation between the peroral and transnasal data, with a correlation coefficient of <it>r </it>= 0.925. On the basis of the regression line calculated using these data, the formula TNG (cm) = 1.1 × TOG (cm) was developed. Using this formula, localization details obtained with one method can be converted into those for the other method.</p> <p>Conclusions</p> <p>There is a strong correlation between the localization details obtained with the transnasal and transoral examination methods. The formula for converting localization details from one method to the other, presented here for the first time, is practicable for everyday use and allows rapid conversion.</p