Circular Deoxyribonucleic Acid Research Articles

Prevalence of HBV genotypes among patients attending Moi Teaching and Referral Hospital liver clinic.

Hepatitis B virus (HBV) belongs to the genus Orthohepadnavirus, of Hepadnaviridae family, smallest human deoxyribonucleic acid (DNA) virus with 3200 bp in a partially double-stranded circular DNA. Globally, about 2 billion people are infected with over 65 million of the chronically infected residing in Africa. Ten HBV genotypes (A-J) have been reported across the globe. Based on the World Health Organization (WHO) African Regions including Kenya have high HBV prevalence rates yet the data on prevalence rates of the various HBV genotypes and their associated biomarkers is very scanty. A cross-sectional descriptive study with purposive sampling was conducted in which a census of patients with chronic Hepatitis B (CHB) with history >6-month were reviewed for eligibility. Demographics data was abstracted from patient files and blood samples drawn for genotyping, viral load using Rotor gene Q Polymerase Chain Reaction (PCR) equipment, Hepatitis B surface Antigen (HBsAg), Hepatitis B envelope antigen (HbeAg) and Hepatitis B core antibody (Anti-HBc) using Cobas e411 machine. Out of a total of 83 patients, 43 (52%) were eligible; males 29 (67.4%), females 14 (32.6%) with mean ages of 35.1±10.8 and 34.3±9.3 respectively. Genotypes A were 34(79.1%), B were 5(11.6%), C-D were 0 while E-J were 9(20.9%). All cases of genotype B were associated with co-infection of genotype A. Majority were HBeAg negative with HBV DNA >10 IU/ml (81.4% and 86.0% respectively) with distribution among all the genotypes. Across genotypes, viral load mean percentage comparisons were: A vs. A/B = 2600 (p = 0.09), A vs. E-J = 5260 (p = 0.09) and A/B vs. E-J = 200 (p = 0.28). The most prevalent genotype was A followed by mixed co-infection of genotype A/B. Genotype A was associated with HBV DNA viral loads > 10IU/ml and high rates of HBeAg negativity. Genotypes E-J were also detected though not characterized.

Prevalence of HBV genotypes among patients attending Moi Teaching and Referral Hospital liver clinic.

Hepatitis B virus (HBV) belongs to the genus Orthohepadnavirus, of Hepadnaviridae family, smallest human deoxyribonucleic acid (DNA) virus with 3200 bp in a partially double-stranded circular DNA. Globally, about 2 billion people are infected with over 65 million of the chronically infected residing in Africa. Ten HBV genotypes (A-J) have been reported across the globe. Based on the World Health Organization (WHO) African Regions including Kenya have high HBV prevalence rates yet the data on prevalence rates of the various HBV genotypes and their associated biomarkers is very scanty. A cross-sectional descriptive study with purposive sampling was conducted in which a census of patients with chronic Hepatitis B (CHB) with history >6-month were reviewed for eligibility. Demographics data was abstracted from patient files and blood samples drawn for genotyping, viral load using Rotor gene Q Polymerase Chain Reaction (PCR) equipment, Hepatitis B surface Antigen (HBsAg), Hepatitis B envelope antigen (HbeAg) and Hepatitis B core antibody (Anti-HBc) using Cobas e411 machine. Out of a total of 83 patients, 43 (52%) were eligible; males 29 (67.4%), females 14 (32.6%) with mean ages of 35.1±10.8 and 34.3±9.3 respectively. Genotypes A were 34(79.1%), B were 5(11.6%), C-D were 0 while E-J were 9(20.9%). All cases of genotype B were associated with co-infection of genotype A. Majority were HBeAg negative with HBV DNA >10 IU/ml (81.4% and 86.0% respectively) with distribution among all the genotypes. Across genotypes, viral load mean percentage comparisons were: A vs. A/B = 2600 (p = 0.09), A vs. E-J = 5260 (p = 0.09) and A/B vs. E-J = 200 (p = 0.28). The most prevalent genotype was A followed by mixed co-infection of genotype A/B. Genotype A was associated with HBV DNA viral loads > 10IU/ml and high rates of HBeAg negativity. Genotypes E-J were also detected though not characterized.

Hepatitis B e Antigen-Negative Single Hepatocyte Analysis Shows Transcriptional Silencing and Slow Decay of Infected Cells With Treatment.

Nucleos(t)ide analogues (NUCs) rarely cure chronic hepatitis B (CHB) because they do not eliminate covalently closed circular deoxyribonucleic acid, the stable replication template. In hepatitis B e antigen (HBeAg)-positive CHB during NUCs, HBV-infected cells decline slowly and are transcriptionally silenced. Whether these occur in HBeAg-negative CHB is unknown. Using paired liver biopsies separated by 2.7-3.7 years in 4 males with HIV and HBeAg-negative CHB at both biopsies and 1 male with HIV who underwent HBeAg seroconversion between biopsies, we quantified amounts of viral nucleic acids in hundreds of individual hepatocytes. In the 4 persistently HBeAg-negative participants, HBV-infected hepatocytes ranged from 6.2% to 17.7% (biopsy 1) and significantly declined in 3 of 4 by biopsy 2. In the HBeAg seroconverter, the proportion was 97.4% (biopsy 1) and declined to 81.9% at biopsy 2 (P < .05). We extrapolated that HBV eradication with NUCs would take >100 years. At biopsy 1 in the persistently HBeAg-negative participants, 23%-56.8% of infected hepatocytes were transcriptionally inactive-higher than we observed in HBeAg-positive CHB-and significantly declined in 1 of 4 at biopsy 2. In HBeAg-negative CHB on NUCs, the negligible decline in infected hepatocytes is similar to HBeAg-positive CHB, supporting the need for more potent therapeutics to achieve functional cure.

A Systematic Review on Current Trends in the Treatment of Chronic Hepatitis B to Predict Disease Remission and Relapse.

Despite decreasing the prevalence of chronic hepatitis B (CHB), it is still a major health care challenge. Current antiviral regimens aim to suppress hepatitis B virus (HBV) deoxyribonucleic acid (DNA) activity to prevent the risk of hepatic decompensation, liver cirrhosis, and hepatocellular carcinoma (HCC). Currently, pegylated interferon (Peg-IFN) and nucleos(t)ide analogs (NA) are the first-line choices of drugs. Peg-IFN is now discontinued due to its mode of application and side effects. NA is used once daily to suppress HBV DNA activity but has little effect on covalently closed circular DNA (cccDNA), so continuous long-term therapy is required to suppress HBV DNA. Due to this effect, disease remission, relapse, and even clinical flare are common phenomena after the end of treatment (EOT). This review aimed to analyze the current regimens for treating chronic hepatitis B. Their mode of action, duration of treatment, and events after stopping therapy. The review was performed using the preferred reporting items for systematic reviews and meta-analysis (PRISMA) 2020 guidelines. A search was undertaken in PubMed, PubMed Central, Google Scholar, and ScienceDirect. Screening of articles was carried out to find relevant and appropriate articles. Articles were then quality-checked before inclusion. Our analysis showed that long-term finite therapy with nucleoside analogs could improve clinical outcomes and suppress viral DNA activity. However, a functional cure, loss of hepatitis B surface antigen (HBsAg), is rarely achieved. The decision to end treatment depends on quantitative HBsAg level (qHBsAg), alanine aminotransferase (ALT), HBV DNA (deoxyribonucleic acid), hepatitis B e antigen (HBeAg), and fibrosis assessment. It is concluded that patients with HBeAg negative without cirrhosis can be easily withdrawn from treatment if they have long-term viral remission and a high HBsAg loss rate. However, patients with positive HBeAg should continue treatment because there is a high chance of disease relapse and even acute flare. To predict whether patients will benefit from EOT, some immunomodulatory markers are studied, including interleukin (IL-20, IL-8), fas ligand (FASGL), and IFN gamma. Although these factors are reliable, none pose an independent effect on disease remission. Combination therapy (IFN alpha + oral nucleoside analogs) is promising but has clinical shortcomings.

In vitro and in silico binding studies of phytochemical isochroman with calf thymus DNA using multi-spectroscopic and computational modelling techniques

A wide range of therapeutic molecules uses deoxyribonucleic acid (DNA) as an intracellular target. The interaction of small molecules to DNA is a key feature in pharmacology and plays a vital role in the development of novel and more efficient drugs with increased selective activity and enhanced therapeutic effectiveness. Isochroman (IC) is a constituent of Olea europea plant, which has been shown to exhibit several beneficial pharmacological activities. At present, its interaction studies using calf thymus DNA (ct-DNA) have not been explained. A set of multi-spectroscopic techniques has been performed to determine the interaction mechanism of isochroman with ct-DNA. Absorption spectra and quenching in fluorescence studies show that isochroman and ct-DNA form a complex. The static mode of quenching was determined by the Stern-Volmer plot. The value of binding constant, Kb = 4.0 × 103 M−1 revealed moderate type of binding. Effects of single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) and ionic strength were studied to examine the isochroman binding to ct-DNA. Potassium iodide (KI) quenching effects and competitive binding studies clearly showed that isochroman binds in the minor groove of ct-DNA. Circular dichroic and DNA melting experiments also confirmed these results. The experimental outputs were further corroborated via in silico computational modelling studies. Lipinski’s rule of 5 and SwissADME showed drug-likeness and oral bioavailability scores. Protox ІІ online software predicts oral and organ toxicity. Communicated by Ramaswamy H. Sarma

DNA Supramolecular Assembly on Micro/Nanointerfaces for Bioanalysis.

Facing increasing demand for precision medicine, materials chemistry systems for bioanalysis with accurate molecular design, controllable structure, and adjustable biological activity are required. As a genetic biomacromolecule, deoxyribonucleic acid (DNA) is created via precise, efficient, and mild processes in life systems and can in turn precisely regulate life activities. From the perspective of materials chemistry, DNA possesses the characteristics of sequence programmability and can be endowed with customized functions by the rational design of sequences. In recent years, DNA has been considered to be a potential biomaterial for analysis and has been applied in the fields of bioseparation, biosensing, and detection imaging. To further improve the precision of bioanalysis, the supramolecular assembly of DNA on micro/nanointerfaces is an effective strategy to concentrate functional DNA modules, and thus the functions of DNA molecules for bioanalysis can be enriched and enhanced. Moreover, the new modes of DNA supramolecular assembly on micro/nanointerfaces enable the integration of DNA with the introduced components, breaking the restriction of limited functions of DNA materials and achieving more precise regulation and manipulation in bioanalysis. In this Account, we summarize our recent work on DNA supramolecular assembly on micro/nanointerfaces for bioanalysis from two main aspects. In the first part, we describe DNA supramolecular assembly on the interfaces of microscale living cells. The synthesis strategy of DNA is based on rolling-circle amplification (RCA), which generates ultralong DNA strands according to circular DNA templates. The templates can be designed with complementary sequences of functional modules such as aptamers, which allow DNA to specifically bind with cellular interfaces and achieve efficient cell separation. In the second part, we describe DNA supramolecular assembly on the interfaces of nanoscale particles. DNA sequences are designed with functional modules such as targeting, drug loading, and gene expression and then are assembled on interfaces of particles including upconversion nanoparticles (UCNPs), gold nanoparticles (AuNPs), and magnetic nanoparticle (MNPs). The integration of DNA with these functional particles achieves cell manipulation, targeted tumor imaging, and cellular regulation. The processes of interfacial assembly are well controlled, and the functions of the obtained bioanalytical materials can be flexibly regulated. We envision that the work on DNA supramolecular assembly on micro/nanointerfaces will be a typical paradigm for the construction of more bioanalytical materials, which we hope will facilitate the development of precision medicine.

Surrogate Markers for Hepatitis B Virus Covalently Closed Circular DNA.

Chronic infection with the hepatitis B virus (HBV) is one of the most common causes of liver disease worldwide. Chronic HBV infection is currently incurable because of the persistence of the viral template for the viral transcripts, covalently closed circular deoxyribonucleic acid (cccDNA). Detecting changes in cccDNA transcriptional activity is key to understanding fundamental virology, determining the efficacy of new therapies, and deciding the optimal clinical management of HBV patients. In this review, we summarize surrogate circulating biomarkers that have been used to infer cccDNA levels and activity in people with chronic hepatitis B. Moreover, we outline the current shortcomings of the current biomarkers and highlight the clinical importance in improving them and expanding their use.

Circle-Seq reveals genomic and disease-specific hallmarks in urinary cell-free extrachromosomal circular DNAs.

BackgroundExtrachromosomal circular deoxyribonucleic acid (eccDNA) is evolving as a valuable biomarker, while little is known about its presence in urine.MethodsHere, we report the discovery and analysis of urinary cell‐free eccDNAs (ucf‐eccDNAs) in healthy controls and patients with advanced chronic kidney disease (CKD) by Circle‐Seq.ResultsMillions of unique ucf‐eccDNAs were identified and comprehensively characterised. The ucf‐eccDNAs are GC‐rich. Most ucf‐eccDNAs are less than 1000 bp and are enriched in four pronounced peaks at 207, 358, 553 and 732 bp. Analysis of the genomic distribution of ucf‐eccDNAs shows that eccDNAs are found on all chromosomes but enriched on chromosomes 17, 19 and 20 with a high density of protein‐coding genes, CpG islands, short interspersed transposable elements (SINEs) and simple repeat elements. Analysis of eccDNA junction sequences further suggests that microhomology and palindromic repeats might be involved in eccDNA formation. The ucf‐eccDNAs in CKD patients are significantly higher than those in healthy controls. Moreover, eccDNA with miRNA genes is highly enriched in CKD ucf‐eccDNA.ConclusionsThis work discovers and provides the first deep characterisation of ucf‐eccDNAs and suggests ucf‐eccDNA as a valuable noninnvasive biomarker for urogenital disorder diagnosis and monitoring.

Relationship between Maternal PBMC HBV cccDNA and HBV Serological Markers and its Effect on HBV Intrauterine Transmission

ObjectiveTo investigate the relationship between maternal peripheral blood mononuclear cells (PBMC) hepatitis B virus (HBV) covalenty closed circular deoxyribonucleic acid (cccDNA) and other HBV serological markers and its effects on HBV intrauterine transmission. MethodsWe enrolled 290 newborns and their hepatitis B surface antigen (HBsAg) positive mothers. HBV cccDNA in PBMC and HBV DNA in serum were detected by a real-time PCR-TaqMan probe while HBV serological markers were detected with an electrochemiluminescence immunoassay. ResultsThere was a positive correlation between the levels of PBMC HBV cccDNA and serum HBV DNA and HBeAg (r = 0.436 and 0.403, P < 0.001). The detection rate of pattern A [‘HBsAg (+), HBeAg (+), and anti-HBc (+)’] was significantly higher in the PBMC HBV cccDNA positive group than in the control group (χ2 = 48.48, P < 0.001). There was a significant association between HBV intrauterine transmission and PBMC HBV cccDNA (χ2 = 9.28, P = 0.002). In the presence of serum HBV DNA, HBeAg, and PBMC HBV cccDNA, the risk of HBV intrauterine transmission was three times higher (OR = 3.69, 95% CI: 1.30-10.42) than that observed in their absence. The risk of HBV intrauterine transmission was the greatest (OR = 5.89, 95% CI: 2.35-14.72) when both PBMC HBV cccDNA and pattern A were present. A Bayesian network model showed that maternal PBMC HBV cccDNA was directly related to HBV intrauterine transmission. ConclusionPBMC HBV cccDNA may be a direct risk factor for HBV intrauterine transmission. Our study suggests that serological markers could be combined with PBMC-related markers in prenatal testing.

Viral Biomarkers in Chronic HBeAg Negative HBV Infection.

Viral biomarkers are important tools for monitoring chronic hepatitis B virus (HBV) hepatitis B early antigen (HBeAg) negative infection, both in its natural course as well as during and after treatment. The biomarkers consist of antibodies against viral epitopes, viral proteins, and molecular surrogate markers of the quantity and transcriptional activity of the stable episomal HBV covalently closed circular DNA (cccDNA) which is located in the nuclei of the infected hepatocytes. HBV deoxyribonucleic acid (DNA) or else viral load measurement in plasma or serum is a marker of HBV replication of major clinical importance. HBV DNA is used for staging and treatment monitoring as described in international scientific guidelines. Quantification of HBV antigens, mainly hepatitis B surface antigen (HBsAg) as well as Hepatitis B core related antigen (HBcrAg), play an important yet secondary role, especially in cases of low or undetectable HBV DNA and has been evaluated for the classification of the inactive carrier state, as a predictor of subsequent HBsAg clearance, treatment outcome, and development of hepatocellular carcinoma (HCC). The measurement of the replicative intermediate HBV RNA in serum is currently evaluated and may also prove to be a significant biomarker particularly in patients treated with nucleot(s)ide analogs. This review focuses on the viral biomarkers mentioned above and their role in HBV, HBeAg negative, infection.

Detection of HBV DNA and antigens in HBsAg-positive patients with primary hepatocellular carcinoma

Hepatitis B virus (HBV) markers include HBV deoxyribonucleic acid (DNA) and HBV antigens. The former involves HBV covalently closed circular DNA (cccDNA) as well as total HBV DNA, whereas the latter involves HBsAg, HBcAg, and HBx. Samples of tumor and adjacent non-tumor liver tissue were collected from 28 HBV-associated HCC patients. Intrahepatic total HBV DNA and cccDNA were measured using the real-time PCR Taqman assay. HBV antigens in hepatocytes were detected using immunohistochemical staining. Intrahepatic levels of total HBV DNA or cccDNA in HCC patients with different intrahepatic HBV antigen expression patterns were compared, and the correlation between serum HBV DNA and intrahepatic HBV DNA was analyzed. No significant differences in intrahepatic cccDNA levels were observed between tumor and non-tumor liver tissue (median -3.00 vs. -2.30 log copies/cell, P=0.298). However, the tumor tissue had significantly higher levels of total HBV DNA (median -0.60 vs. -1.24 log copies/cell, P=0.045) but significantly lower proportion of intrahepatic HBV DNA in the form of cccDNA (median 0.25% vs. 4%, P=0.023) than the corresponding values in the non-tumor tissue. Also, HBV antigen levels were lower in the tumor tissue than in the non-tumor tissue. Analysis of the correlation between serum HBV DNA and intrahepatic HBV DNA indicated that the viral status in the tumor tissue was more complicated in HBV-HCC patients-the detected serum HBV DNA failed to accurately reflect intrahepatic viral load. HBV DNA may play an important role in hepatocarcinogenesis, and cccDNA was not the predominant form of HBV DNA in the tumor tissue.

Symmetries of deoxyribonucleic acid (DNA) and related molecules

The basic groups and some atomic groups in polynucleotide long-chains of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) have been used as the basic structural unit to analyze their molecular symmetry. The basic groups have been treated as the same structural unit in spite of the fact that they have very different intrinsic characteristics. In this paper, we developed bi-double-valued H- and P-representations to distinguish between the various structural units in DNA and RNA. We simulated their molecular symmetries based on our earlier work on the symmetry analysis of cylinder and torus carbon nanotubes. The symmetric and antisymmetric components of some gene segments with some transformations have been calculated in the bi-double-valued HP-representation space. By analyzing the genetic code table, we investigated the distributive features of codons in corresponding H- and P-representations. The results indicate that some characteristics of H- and P-representation carry messages of the corresponding genetic processes in DNA. In addition, we analyzed some topologic features and Mobius twists of torus groups for circular DNA.

Synthesis, Characterization and DNA Cleavage of Copper(II) Complex with D,L-Dithiothreitol

Purpose: To study deoxyribonucleic acid (DNA) shearing capability of copper(II) complex of dithiothreitol (DTT) and to fevaluate its potential application in cancer therapy. Methods: A parrot green complex was synthesized by grinding copper acetate monohydrate and DTT in 1:2 molar ratio in a mortar until no fumes of acetic acid were observed. The complex was characterized using attenuated total reflectance-Fourier transform infra-red (ATR-FTIR), and x-ray diffraction (XRD) techniques. Further information was also collected through Karl Fischer titration, thermogravimetric analysis (TGA) and (magnetic moment. Cleavage of DNA was determined by agarose gel electrophoresis. The gel was then stained, analyzed and photographed under ultraviolet (UV) light. Results: ATR-FTIR confirmed the formation of copper(II) complex with DTT by binding through thiol group based on the disappearance of the thiol (-SH) stretching peak at 2545 cm -1 . The crystalline structure was elucidated by a sharp intense peak at 38.520 in XRD spectrum while the octahedral geometry of complex was inferred from a magnetic moment of 1.72 B.M. The results for water content obtained by Karl Fischer titration and TGA revealed that water molecules are not part of the coordination sphere of the complex. Cleavage study of DNA showed that the complex completely sheared the circular DNA compared to pure DTT. Conclusion: Solvent free synthesis of Copper(II)-DTT complex has been successfully achieved, and an anhydrous complex with octahedral geometry obtained. The complex has a greater potential to shear DNA molecule than pure DTT. Keywords: DNA shearing, Copper(II) complex, Dithiothreitol, Attenuated total reflectance-Fourier transform infra-red, Karl Fischer titration, Magnetic moment

Relationship between the expression of HBV DNA, HBV cccDNA in human ovary tissues and the HBV intrauterine infection

To investigate the relationship between hepatitis B virus (HBV) deoxyribonucleic acid (DNA) and HBV covalently closed circular DNA (cccDNA) in the ovary and HBV intrauterine infection. HBV DNA and HBV cccDNA were assayed in the ovaries of 33 pregnant women who were positive for HBV DNA, tested by Fluorescent quantitative polymerase chain reaction (FQ-PCR). The level of HBV mark (HBVM) and the content of HBV DNA in peripheral blood of infants were measured by chemoluminescence and FQ-PCR methods respectively. The overall positive rate for both HBV DNA and HBV cccDNA in ovarian samples was 51.52% (17/33). The rate on intrauterine infection among infants was 12.12% (4/33) and all the 4 infected infants were delivered from mothers with normal hepatic function. When HBV DNA and HBV cccDNA were both positive, the rate of intrauterine infection in infants was significantly higher than those who were with both negative results (P < 0.05). Levels of HBV cccDNA and the rate of positive samples were significantly higher in mothers with infants who appeared to have had intrauterine infection than those did not (P < 0.01 and < 0.05, respectively). HBV infection could be discovered in the human ovary and might be transmitted to the filial generation via ovum.

English

Division of the ancestral prokaryotic genome into two circular double-stranded deoxyribonucleic acid (DNA) molecules by genetic recombination, is a basis for the future separate evolution of the nuclear and mitochondrial gene compartment. This suggests monophyletic origin of both mitochondrion and nucleus. Presumed organism which genome undergoes genetic recombination has to be searched among an aerobic, oxygen non-producing archaeon with no rigid cell wall, but a plasma membrane, probably an crenarchaeota containing functional bacteriochlorophyll a synthase gene and histones. In this proposal, origin of eukaryotes occur by a three-steps. First, replication fork pauses and collapses generating a breakage in the genome of archaeal ancestor of eukaryotes. Second, the double-strand break can be repaired intergenomically by complementary strands invasion. Third, this duplicated genome can be fissioned into two compartments by reciprocal genetic recombination. Scenario is accomplished by aberrant fission of the inner membane surrounding separately those two compartments. Key words: Origin of nucleus, origin of mitochondrion.

Inhibition of hepatitis B virus and human immunodeficiency virus (HIV-1) replication by Warscewiczia coccinea (Vahl) Kl. (Rubiaceae) ethanol extract

The primary objective of this study was to search for natural products capable of inhibiting hepatitis B virus (HBV) replication. The research design, methods and procedures included testing hydro-alcoholic extracts (n = 66) of 31 species from the Venezuelan Amazonian rain forest on the cell line HepG2 2.2.15, which constitutively produces HBV. The main outcomes and results were as follows: the species Euterpe precatoria, Jacaranda copaia, Jacaranda obtusifolia, Senna silvestris, Warscewiczia coccinea and Vochysia glaberrima exerted some degree of inhibition on HBV replication. The leaves of W. coccinea showed a significant antiviral activity: 80% inhibition with 100 µg mL−1 of extract. This extract also exerted inhibition on covalently closed circular deoxyribonucleic acid (cccDNA) production and on HIV-1 replication in MT4 cells (more than 90% inhibition with 50 µg mL−1 of extract). Initial fractionation using organic solvents of increasing polarity and water showed that the ethanol fraction was responsible for most of the antiviral inhibitory activities of both the viruses. It was concluded that Warscewiczia coccinea extract showed inhibition of HBV and HIV-1 replication. Bioassay-guided purification of this fraction may allow the isolation of an antiviral compound with inhibitory activity against both viruses.

Serum hepatitis B virus DNA before liver transplantation correlates with HBV reinfection rate even under successful low-dose hepatitis B immunoglobulin prophylaxis

PurposeThe combination of hepatitis B immunoglobulin (HBIg) and nucleos(t)ide analogues has been accepted as the best treatment to control hepatitis B recurrence after orthotopic liver transplantation (OLT). However, the optimal dose of HBIg remains unclear. We have previously reported that high-dose HBIg in the early period followed by low-dose HBIg with nucleos(t)ide analogues offers reliable and cost-effective control of hepatitis B recurrence. The aim of this study was to investigate intrahepatic hepatitis B virus (HBV) reinfection status with our clinically successful protocol.MethodsWe quantified levels of intrahepatic HBV covalently closed circular (ccc) deoxyribonucleic acid (DNA) and serum hepatitis B core-related antigen (HBcrAg), a new serological marker that can estimate intrahepatic cccDNA levels. Nucleos(t)ide analogues were administered in all cases.ResultsNo patients showed recurrence of hepatitis B surface antigen (HBsAg) or HBV-DNA. However, HBV, cccDNA, and HBcrAg were positive in 57% and 48% of patients after OLT, respectively. Pre-OLT serum HBV-DNA and HBcrAg levels correlated linearly with post-OLT cccDNA levels (r = 0.534, P < 0.05, and r = 0.634, P < 0.05, respectively). High serum HBV-DNA and HBcrAg levels, particularly with >3 log10 copies/mL and >4 log10 IU/mL, respectively, at the time of OLT, were associated with high levels of post-OLT cccDNA. Even with our successful protocol, nearly half of patients showed HBV reinfection.ConclusionsPatients with high serum HBV-DNA and HBcrAg levels before OLT (particularly >3 log10 copies/mL and >4 log10 IU/mL, respectively) should be followed with care for HBV recurrence.

Finding of a zero linking number topoisomer

It is generally assumed that native deoxyribonucleic acid (DNA) is a right-handed double helix. A reasonable deduction is that during replication, the two parental strands have to unwind very quickly. However, this surmised quick unwinding is problematic and has never been proven experimentally. It is hypothesized that the two strands of DNA are winding with each other ambidextrously rather than plectonemically. The successful assembling and disassembling of a zero linking number topoisomer supports this hypothesis. It was further proven by quick separation of singly nicked DNA. The new DNA model was also verified by the “figure 8” structure, which is the annealing product of two single-stranded circular DNA with a 2 kb complementary insert in opposite directions. These experimental results are hard to be explained by the traditional Watson–Crick model. The significance of this finding in the understanding of DNA replication is briefly discussed.

Nonlinear current-voltage characteristics measured across circular deoxyribonucleic acid (DNA) molecule bundles

We measured current-voltage characteristics of circular deoxyribonucleic acid (DNA) bundle samples embedded in a water mantle lying on a nylon porous membrane between vacuum-evaporated gold electrodes. The nonlinear behavior observed at room temperature on samples of different molecular sizes and variable concentration was interpreted as a long-range conduction mechanism that takes place by means of charge hopping through the network of molecules. A tunneling process acting as an additional transport channel inside single molecules between energetically appropriate bases was inferred. Our data also suggest at low bias a thermionic emission mechanism by means of which the charges move from one electrode, overcoming a potential barrier. Characteristic energies involved in the transport were reproducibly measured.

Presence of intrahepatic (total and ccc) HBV DNA is not predictive of HBV recurrence after liver transplantation

Previous studies reported that hepatitis B virus (HBV) deoxyribonucleic acid (DNA) can be detected in livers of patients who received transplants for hepatitis B despite the absence of serological markers of HBV recurrence. Quantification of HBV DNA was not performed and presence of covalently closed circular (ccc) DNA was not analyzed in most studies. We aimed to quantify total and ccc HBV DNA in explant liver and post-orthotopic liver transplantation (OLT) biopsies and to correlate the values with HBV recurrence post-OLT. Frozen liver tissue from 34 patients (9 with explant liver only, 9 with explant liver and post-OLT liver biopsies, and 16 with post-OLT biopsies only) in the National Institutes of Health HBV-OLT study was examined using real-time polymerase chain reaction (PCR). Among the 18 patients with explant liver, 7 were hepatitis B e antigen (HBeAg)-positive, 8 had detectable serum HBV DNA, and 10 received antiviral therapy prior to OLT. Total and ccc HBV DNA was detected in explant livers of 17 and 16 patients, respectively. Of the 10 patients who received antiviral therapy pre-OLT, serum HBV DNA was undetectable in 8 at transplantation but 7 had detectable total and ccc HBV DNA in their explant liver. Of the 25 patients with post-OLT biopsies, total HBV DNA was detected in 83% and ccc DNA in 17% of 47 biopsies, although only 2 patients had HBV recurrence. In conclusion, total and ccc HBV DNA could be detected in explant livers of most patients despite antiviral therapy pre-OLT. Total but not ccc HBV DNA could be detected in post-OLT liver biopsies of most patients despite undetectable serum HBV DNA and hepatitis B surface antigen (HBsAg). Our findings suggest that occult HBV reinfection occurs in most HBV patients after OLT and continued administration of appropriate prophylactic therapy is important in preventing overt HBV recurrence.