Virus-host interplay in hepatitis B virus infection and epigenetic treatment strategies.

Worldwide, chronic hepatitis B virus (HBV) infection is a major health problem and no cure exists. Importantly, hepatocyte intrusion by HBV particles results in a complex deregulation of both viral and host cellular genetic and epigenetic processes. Among the attempts to develop novel therapeutic approaches against HBV infection, several options targeting the epigenomic regulation of HBV replication are gaining attention. These include the experimental treatment with 'epidrugs'. Moreover, as a targeted approach, the principle of 'epigenetic editing' recently is being exploited to control viral replication. Silencing of HBV by specific rewriting of epigenetic marks might diminish viral replication, viremia, and infectivity, eventually controlling the disease and its complications. Additionally, epigenetic editing can be used as an experimental tool to increase our limited understanding regarding the role of epigenetic modifications in viral infections. Aiming for permanent epigenetic reprogramming of the viral genome without unspecific side effects, this breakthrough may pave the roads for an ambitious technological pursuit: to start designing a curative approach utilizing manipulative molecular therapies for viral infections in vivo.

Infección oculta por el virus de la hepatitis B en pacientes sometidos a trasplante hepático / Occult Hepatitis B Virus Infection in Liver Transplant Patients

Introducción: la infección oculta por el virus de la hepatitis B (VHB) se caracteriza por la presencia del genoma viral en suero y/o tejido hepático de individuos negativos para el antígeno de superficie HBsAg. La infección oculta se ha asociado con el desarrollo de cirrosis y carcinoma hepatocelular. Objetivo: identificar casos de infección oculta por el VHB en pacientes con diagnóstico de cirrosis y carcinoma hepatocelular, sometidos a trasplante hepático. Materiales y métodos: entre febrero de 2013 y marzo de 2014 fueron obtenidas muestras de explante hepático provenientes de pacientes con diagnóstico de cirrosis y/o carcinoma hepatocelular. Se detectó el genoma del VHB mediante amplificación de tres regiones del genoma viral (S, Core y X). Las muestras positivas se confirmaron por reacción en cadena de la polimerasa (PCR) en tiempo real para la región S. Resultados: se analizaron 15 muestras de tejido hepático, y en dos (13,3%) se detectó el genoma del VHB mediante PCR anidada para la región S y por PCR semianidada para la región X, resultado confirmado por PCR en tiempo real. Estas muestras provenían de pacientes negativos para los marcadores serológicos de infección por el VHB, anti-HBc y anti-HBs. Conclusión: la frecuencia de infección oculta reportada en este estudio es similar a lo reportado en Brasil en muestras de biopsias obtenidas de pacientes con hepatitis crónica. Estudios adicionales son necesarios para estimar la frecuencia de infección oculta por VHB (OBI) en pacientes con hepatopatías terminales en Colombia

Introduction: Occult hepatitis B virus infection is characterized by the presence of the viral genome in serum and/or liver tissue from individuals who test negative for the HBsAg surface antigen. Occult infection has been associated with the development of cirrhosis and hepatocellular carcinoma. Objective: The objective of this study was to identify cases of occult hepatitis B virus infection in patients with cirrhosis and/or hepatocellular carcinoma undergoing liver transplantation. Materials and methods: Between February 2013 and March 2014 hepatic explant samples were obtained from patients with cirrhosis and/or hepatocellular carcinoma. The hepatitis B virus genome was detected by amplification of three regions of the viral genome (S, Core and X). Positive samples were confirmed by real-time PCR for the S region. Results: Fifteen hepatic tissue samples were analyzed. The genome of the hepatitis B virus was detected in two (13.3%) samples by nested PCR for the S region and by semi-nested PCR for region X. The results were confirmed by real-time PCR. These samples came from patients who had tested negative for anti-HBc and anti-HBs serological markers for hepatitis B virus infection. Conclusion: The frequency of occult infection reported in this study is similar to that reported in Brazil in biopsy specimens obtained from patients with chronic hepatitis. Additional studies are needed to estimate the frequency of occult hepatitis B in patients with end-stage liver disease in Colombia

Analysis of hepatitis B virus genotypes by restriction fragment length polymorphism / Análisis de genotipos del virus de la hepatitis B mediante el análisis de polimorfismos de longitud de fragmentos de restricción

Introduction: Ten viral genotypes (A-J) distributed in all continents have been described for hepatitis B virus (HBV). One of the methodologies for determining the viral genotype is the restriction fragment length polymorphism (RFLP) technique, a simple and relatively inexpensive method, albeit with some limitations. Objective: The initial objective of the project was to identify the HBV genotypes by RFLP in serum samples obtained from patients and blood donors. However, due to the discrepancies of RFLP patterns it was also necessary to perform phylogenetic genotyping and in silico analysis of HBV sequences. Materials and methods: We obtained 56 serum samples. DNA extraction was followed by PCR amplification of a fragment of HBV ORF S. We analyzed PCR products by RFLP with Alw I, Bsr I, Cfr I, Hpa II and Sty I, and we sequenced some. We compared the patterns obtained with those in previous reports. We also performed RFLP analysis in silico since we found differences between the patterns expected and those obtained. Results: We identified genotypes A and F, subgenotype F3, in the samples. This result is in agreement with those of previous studies carried out in Colombia; indeed, subgenotype F3 is the most frequent in the Andean region of the country, while genotype A is the most frequent HBV genotype in the western region (department of Chocó). Based on the in silico analysis of 229 HBV sequences from GenBank and 11 sequences of this study, we identified the RLFP pattern for genotype F, subgenotype F3, and we described some modifications of genotype A RFLP patterns. Conclusions: We identified the single nucleotide polymorphism pattern for genotype F, subgenotype F3, by in silico analysis and sequencing. Further robust in silico analyses are necessary to validate the RFLP patterns of HBV genotype and subgenotypes.

Introducción. Se han descrito diez genotipos (A-J) del virus de la hepatitis B (HBV) que están distribuidos en todos los continentes. Una de las técnicas utilizadas para determinar el genotipo viral es el análisis del polimorfismo de longitud de los fragmentos de restricción, un método simple y económico, pero con algunas limitaciones. Objetivo. El objetivo inicial del estudio fue identificar el genotipo del HBV mediante RFLP en muestras de suero obtenidas de pacientes y donantes de sangre. Sin embargo, por las discrepancias observadas en los patrones de RFLP fue necesario realizar análisis filogenéticos y un análisis in silico de secuencias del HBV. Materiales y métodos. Se obtuvieron 56 muestras de suero. Tras la extracción de ADN, se amplificó un fragmento del ORF S del HBV mediante reacción en cadena de la polimerasa, cuyos productos se analizaron por RFLP con las enzimas Alw I, Bsr I, Cfr I, Hpa II y Sty I, y algunos se secuenciaron. Los patrones obtenidos se compararon con los reportados previamente. Se efectuó un análisis in silico de RFLP en consideración de las diferencias entre los patrones esperados y los observados. Resultados. Se identificaron los genotipos A y F, subgenotipo F3, en las muestras. Este resultado coincide con lo descrito en estudios previos en los que se ha demostrado que el genotipo F, subgenotipo F3, es prevalente en la población de la región andina del país, en tanto que el genotipo A predomina en el occidente (departamento del Chocó). Con base en el análisis in silico de 229 secuencias virales obtenidas del GenBank y las 11 secuencias de este estudio, se caracterizó un nuevo patrón de RFLP específico para el genotipo F, subgenotipo F3, y se describieron algunas modificaciones en el patrón de RFLP del genotipo A, subgenotipo A1. Conclusiones. Se caracterizó el patrón de genotipificación del genotipo F, subgenotipo F3, del HBV mediante RFLP, análisis in silico y secuenciación. Se requieren nuevos análisis in silico con un número mayor de secuencias para validar los patrones de RFLP de los genotipos y subgenotipos del VHB.

Analysis of hepatitis B virus genotypes by restriction fragment length polymorphism.

INTRODUCTION: Ten viral genotypes (A-J) distributed in all continents have been described for hepatitis B virus (HBV). One of the methodologies for determining the viral genotype is the restriction fragment length polymorphism (RFLP) technique, a simple and relatively inexpensive method, albeit with some limitations. OBJECTIVE: The initial objective of the project was to identify the HBV genotypes by RFLP in serum samples obtained from patients and blood donors. However, due to the discrepancies of RFLP patterns it was also necessary to perform phylogenetic genotyping and in silico analysis of HBV sequences. MATERIALS AND METHODS: We obtained 56 serum samples. DNA extraction was followed by PCR amplification of a fragment of HBV ORF S. We analyzed PCR products by RFLP with AlwI, BsrI, CfrI, HpaII and StyI, and we sequenced some. We compared the patterns obtained with those in previous reports. We also performed RFLP analysis in silico since we found differences between the patterns expected and those obtainedResults: We identified genotypes A and F, subgenotype F3, in the samples. This result is in agreement with those of previous studies carried out in Colombia; indeed, subgenotype F3 is the most frequent in the Andean region of the country, while genotype A is the most frequent HBV genotype in the western region (department of Chocó). Based on the in silico analysis of 229 HBV sequences from GenBank and 11 sequences of this study, we identified the RLFP pattern for genotype F, subgenotype F3, and we described some modifications of genotype A RFLP patterns. CONCLUSIONS: We identified the single nucleotide polymorphism pattern for genotype F, subgenotype F3, by in silico analysis and sequencing. Further robust in silico analyses are necessary to validate the RFLP patterns of HBV genotype and subgenotypes.