Search

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 mechanisms of HBV is crucial for developing new drugs, which—in combination with immune modulators—may contribute to potential cures. This review will explore the current knowledge of HBV intracytoplasmic and nuclear transport, as well as genome repair processes, while drawing comparisons to other viruses with nuclear replication. [ABSTRACT FROM AUTHOR]

Background Hepatitis B virus (HBV) DNA may become integrated into the human genome of infected human hepatocytes. Expression of integrations can produce the surface antigen (HBsAg) that is required for synthesis of hepatitis D virus (HDV) particles and the abundant subviral particles in the blood of HBV- and HDV-infected subjects. Knowledge about the extent and variation of HBV integrations and impact on chronic HDV is still limited. Methods We investigated 50 pieces of liver explant tissue from 5 patients with hepatitis D-induced cirrhosis, using a deep-sequencing strategy targeting HBV RNA. Results We found that integrations were abundant and highly expressed, with large variation in the number of integration-derived (HBV/human chimeric) reads, both between and within patients. The median number of unique integrations for each patient correlated with serum levels of HBsAg. However, most of the HBV reads represented a few predominant integrations. Conclusions The results suggest that HBV DNA integrates in a large proportion of hepatocytes, and that the HBsAg output from these integrations vary >100-fold depending on clone size and expression rate. A small proportion of the integrations seems to determine the serum levels of HBsAg and HDV RNA in HBV/HDV coinfected patients with liver cirrhosis. [ABSTRACT FROM AUTHOR]

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 (7.71 vs. 7.73 and 7.77 log copies/mL, p <.001). On average 80% of the nucleic acid was DNA by quantification in core. The core DNA/RNA ratio was associated with viral load and genotype. In individual patients, the relations between RNA levels in core, S and X were stable over time (n = 29; p =.006). The results suggest that pregenomic RNA is completely reverse transcribed to minus DNA in ≈75% of the virus particles, whereas the remaining 25% contain both RNA and DNA of lengths that reflect variable progress of the polymerase. [ABSTRACT FROM AUTHOR]

Hepatitis B virus (HBV) DNA and RNA were quantified by digital PCR assays in 20-30 tissue pieces from each of 4 liver explants with cirrhosis caused by HBV. The within-patient variability of HBV RNA levels between pieces was up to a 1000-fold. Core RNA and S RNA levels were similar and correlated strongly when replication was high, supporting that transcription was from covalently closed circular DNA (cccDNA). By contrast, enhanced expression of S RNA relative to cccDNA and core RNA in patients with medium-high or low replication supports that HBV surface antigen (HBsAg) can be expressed mainly from integrated HBV DNA in such patients. [ABSTRACT FROM AUTHOR]

Background: Hepatitis B virus (HBV) integration has implications for cancer development and surface antigen (HBsAg) production, but methods to quantify integrations are lacking. The aim of this study was to develop a droplet digital PCR (ddPCR) assay discriminating between circular and integrated HBV DNA, and to relate the distribution between the two forms to other HBV markers.Methods: ddPCR with primers spanning the typical linearization breakpoint in the HBV genome allowed for quantification of the absolute copy numbers of total and circular HBV DNA, and calculation of linear HBV DNA.Results: Analysis of 70 liver biopsies from patients with chronic HBV infection revealed that the fraction of linear HBV DNA, which includes integrations, was higher in HBeAg-negative patients than HBeAg-positive. The ratio between HBsAg and HBV DNA levels in serum correlated with the intrahepatic proportion of linear HBV DNA. Furthermore, ddPCR experiments on serum samples and experiments with nuclease indicated the contribution of encapsidated double-stranded linear DNA and replication intermediates to be limited.Conclusions: The degree of integration of intrahepatic HBV DNA in the HBeAg-negative stage may be higher than previously anticipated, and integrated DNA may explain the persistence of high HBsAg serum levels in patients with low HBV DNA levels. [ABSTRACT FROM AUTHOR]

Detailed knowledge regarding norovirus transmission within hospitals is limited. We investigated a norovirus hospital outbreak affecting 65 patients at five different wards. PCR showed that 61 (94%) of the patients were infected with genotype II.4 strains. Successful Ion Torrent deep sequencing of GII.4 positive samples from 59 patients followed by phylogenetic analysis revealed that all sequences but two clustered into four distinct clades. Two of the clades belonged to GII.4 Sydney 2012, while the other two belonged to GII.4 New Orleans 2009. One of the clades was predominant at two wards, while two clades were predominant at one ward each. The fourth clade was found in sporadic cases at several wards. Thus, at four out of five wards, variants from one clade were predominant. At one ward, a single clade accounted for all cases, while at three wards the predominant clade accounted for 60%-71% of cases. Analysis of quasispecies variation identified positions that could further discriminate between variants from separate wards. The results illustrate a complex transmission of healthcare-associated norovirus infections and show that sequencing can be used to discriminate between related and unrelated cases., Competing Interests: The authors declare no conflict of interest.

Quartz crystal microbalance with dissipation monitoring and total internal reflection fluorescence microscopy have been used to investigate binding of norovirus-like particles (noroVLPs) to a supported (phospho)lipid bilayer (SLB) containing a few percent of H or B type 1 glycosphingolipid (GSL) receptors. Although neither of these GSLs spontaneously form domains, noroVLPs were observed to form micron-sized clusters containing typically up to about 30 VLP copies, especially for B type 1, which is a higher-affinity receptor. This novel finding is explained by proposing a model implying that VLP-induced membrane deformation promotes VLP clustering, a hypothesis that was further supported by observing that functionalized gold nanoparticles were able to locally induce SLB deformation. Because similar effects are likely possible also at cellular membranes, our findings are interesting beyond a pure biophysicochemical perspective as they shed new light on what may happen during receptor-mediated uptake of viruses as well as nanocarriers in drug delivery.