Hepatitis E: virología molecular, epidemiología y patogénesis / Hepatitis E: Molecular virology, epidemiology and pathogenesis

La hepatitis E representa una proporción significativa de las enfermedades hepáticas de transmisión entérica y constituye un importante problema de salud pública, especialmente en los países en vías de desarrollo, principalmente asociada a epidemias debidas a la contaminación de los suministros de agua. El virus de la hepatitis E (VHE) es responsable de infecciones hepáticas agudas autolimitadas de transmisión oral-fecal. En países industrializados la hepatitis E aguda es esporádica, detectada en viajeros procedentes de zonas endémicas pero también en casos esporádicos sin factores de riesgo. El VHE es un virus sin envuelta con genoma de ARN de cadena sencilla en el que se han caracterizado 4 genotipos con un único serotipo. Los genotipos 1 y 2 son los predominantes en los países en desarrollo y tan solo infectan a seres humanos, mientras que los 3 y 4, que predominan en los países industrializados, también infectan a otras especies de mamíferos, especialmente el cerdo, y múltiples evidencias clasifican al VHE como un agente zoonótico. Recientemente se han comunicado casos de infección crónica por este virus en pacientes trasplantados hepáticos y renales. La tasa de mortalidad de la infección por VHE es mayor que la de la hepatitis A. Además de la vía oral-fecal se han comunicado transmisiones parenterales de este virus. Diversas vacunas se hallan actualmente en desarrollo. La severidad de esta infección en algunos grupos de pacientes, especialmente en embarazadas, y la presencia de casos de hepatitis crónica incluso con progresión a cirrosis han suscitado el interés por la aplicación de terapias antivirales con interferón y/o ribavirina (AU)

Hepatitis E represents a significant proportion of enteric transmitted liver diseases and poses a major public health problem, mainly associated with epidemics due to contamination of water supplies, especially in developing countries. Hepatitis E virus (HEV) is responsible for self-limiting acute liver oral-faecal infections. In industrialised countries, acute hepatitis E is sporadic, detected in travellers from endemic areas but also in sporadic cases with no risk factors. HEV is a non-enveloped virus with a single-stranded RNA genome classified into 4 genotypes and a single serotype. Genotypes 1 and 2 only infect humans, and are predominant in the developing countries, while 3 and 4 are predominant in industrialised countries, and also infect other species of mammals, especially pigs, and multiple evidence classifies HEV as a (..) (AU)

Ultra-deep pyrosequencing detects conserved genomic sites and quantifies linkage of drug-resistant amino acid changes in the hepatitis B virus genome.

BACKGROUND: Selection of amino acid substitutions associated with resistance to nucleos(t)ide-analog (NA) therapy in the hepatitis B virus (HBV) reverse transcriptase (RT) and their combination in a single viral genome complicates treatment of chronic HBV infection and may affect the overlapping surface coding region. In this study, the variability of an overlapping polymerase-surface region, critical for NA resistance, is investigated before treatment and under antiviral therapy, with assessment of NA-resistant amino acid changes simultaneously occurring in the same genome (linkage analysis) and their influence on the surface coding region. METHODOLOGY/PRINCIPAL FINDINGS: Serum samples obtained from chronic HBV-infected patients at pre-treatment and during sequential NA treatment with lamivudine, adefovir, and entecavir were analyzed by ultra-deep pyrosequencing (UDPS) using the GS-FLX platform (454 Life Sciences-Roche). The pre-treatment HBV quasispecies was not enriched with NA-resistant substitutions. The frequencies of this type of substitutions at pre-treatment did not predict the frequencies observed during lamivudine treatment. On linkage analysis of the RT region studied, NA-resistant HBV variants (except for rtA181T) were present in combinations of amino acid substitutions that increased in complexity after viral breakthrough to entecavir, at which time the combined variant rtL180M-S202G-M204V-V207I predominated. In the overlapping surface region, NA-resistant substitutions caused selection of stop codons in a significant percentage of sequences both at pre-treatment and during sequential treatment; the rtA181T substitution, related to sW172stop, predominated during treatment with lamivudine and adefovir. A highly conserved RT residue (rtL155), even more conserved than the essential residues in the RT catalytic motif YMDD, was identified in all samples. CONCLUSIONS: UDPS methodology enabled quantification of HBV quasispecies variants, even those harboring complex combinations of amino acid changes. The high percentage of potentially defective genomes, especially in the surface region, suggests effective trans-complementation of these variants.

[Hepatitis E: molecular virology, epidemiology and pathogenesis]. / Hepatitis E: virología molecular, epidemiología y patogénesis.

Hepatitis E represents a significant proportion of enteric transmitted liver diseases and poses a major public health problem, mainly associated with epidemics due to contamination of water supplies, especially in developing countries. Hepatitis E virus (HEV) is responsible for self-limiting acute liver oral-faecal infections. In industrialised countries, acute hepatitis E is sporadic, detected in travellers from endemic areas but also in sporadic cases with no risk factors. HEV is a non-enveloped virus with a single-stranded RNA genome classified into 4 genotypes and a single serotype. Genotypes 1 and 2 only infect humans, and are predominant in the developing countries, while 3 and 4 are predominant in industrialised countries, and also infect other species of mammals, especially pigs, and multiple evidence classifies HEV as a zoonotic agent. Some HEV chronic infections have recently been reported in kidney and liver transplant patients. The mortality rate of HEV infection is greater than hepatitis A. In addition to faecal-oral transmission, parenteral transmission of HEV has also been reported. Several vaccines are currently in development. The severity of this infection in some groups of patients, especially pregnant women, and the occurrence of chronic hepatitis, even with progression to cirrhosis, have raised interest in the application of interferon and/or ribavirin therapy.

Rare alpha-1-antitrypsin variants: are they really so rare?

Alpha-1-antitrypsin (α1-AT) deficiency is mainly evaluated in the diagnostic process of chronic obstructive pulmonary disease (COPD). Around 95% of individuals with severe α1-AT deficiency carry the PI*ZZ genotype. Little is known about the epidemiology of the remaining deficient α1-AT variants, which are called 'rare' due to their low prevalence. The retrospective revision of 3511 α1-AT deficiency determinations performed in Barcelona from 1998 to 2010 detected 1.6% of cases with rare α1-AT alleles, a rate similar to those reported in other European studies. Among these variants, PI*I and PI*Mmalton represented 54% of cases. Hence, the so-called 'rare' α1-AT alleles may not be rare as has been assumed. It would be of interest to implement simple allele-specific molecular biology methods to study the most prevalent rare variants in each region. Augmentation therapy is recommended in patients with emphysema and PI*ZZ genotype, but there is little evidence regarding the implications of rare variants on therapy.

α1-Antitrypsin in fibromyalgia: results of a randomized, placebo-controlled, double-blind and crossover pilot trial.

OBJECTIVE: To assess clinical effect of a human plasma-derived alpha-1 antitrypsin (AAT) concentrate in reducing pain severity of patients with fibromyalgia (FM). METHODS: Thirteen subjects with FM completed a randomized, double-blind, placebo-controlled, crossover study which consisted of 9 weeks trial of AAT or placebo with a washout period of 6 weeks. Primary efficacy endpoint was change on pain severity score, assessed by a daily visual analogue scale (VAS) for pain. Other outcome measures included a tender point score, the Fibromyalgia Impact Questionnaire, (FIQ), the Medical Outcomes Study Short Form 36 (SF-36), the Health Assessment Questionnaire Disability Index (HAQ-DI), the Hospital Anxiety and Depression Scale (HADS) and tiredness score evaluated by VAS. RESULTS: No statistically significant differences were observed in either pain severity or other secondary outcome measures in either of the treatment groups, or between treatment groups in either of the treatment periods. No carryover or order of intervention effect was observed from one treatment to the other. Both investigational interventions were generally well tolerated, and vital signs during the drug infusions were within the respective normal ranges. CONCLUSION: Treatment with a human plasma-derived AAT concentrate did not demonstrate significant improvement over placebo on reducing pain severity and other symptoms of FM. Further research should examine other FM subpopulations and drug doses.

Ultra-deep pyrosequencing analysis of the hepatitis B virus preCore region and main catalytic motif of the viral polymerase in the same viral genome.

Hepatitis B virus (HBV) pregenomic RNA contains a hairpin structure (ε) located in the preCore region, essential for viral replication. ε stability is enhanced by the presence of preCore variants and ε is recognized by the HBV polymerase (Pol). Mutations in the retrotranscriptase domain (YMDD) of Pol are associated with treatment resistance. The aim of this study was to analyze the preCore region and YMDD motif by ultra-deep pyrosequencing (UDPS). To evaluate the UDPS error rate, an internal control sequence was inserted in the amplicon. A newly developed technique enabled simultaneous analysis of the preCore region and Pol in the same viral genome, as well as the conserved sequence of the internal control. Nucleotide errors in HindIII yielded a UDPS error rate <0.05%. UDPS study confirmed the possibility of simultaneous detection of preCore and YMDD mutations, and demonstrated the complexity of the HBV quasispecies and cooperation between viruses. Thermodynamic stability of the ε signal was found to be the main constraint for selecting main preCore mutations. Analysis of ε-signal variability suggested the essential nature of the ε structural motif and that certain nucleotides may be involved in ε signal functions.

Does pre-liver transplant HBV DNA level affect HBV recurrence or survival in liver transplant recipients receiving HBIg and nucleos(t)ide analogues?

BACKGROUND AND AIMS: The risk of recurrent hepatitis B virus (HBV) infection and prognosis of liver transplantation in patients with HBV has dramatically changed with the use of prophylaxis including hepatitis B immune globulin (HBIg) and antiviral agents. METHODS: This study analyzes the prognostic value of HBV DNA level before orthotopic liver transplantation (OLT) and the effect of HBV prophylaxis on rates of HBV recurrence and survival. Between 1988 and 2008, 859 patients underwent OLT in our center; 60 patients had HBV-related liver disease and in 49, HBV DNA was determined by real time-PCR before OLT. Survival and HBV recurrence were analyzed according to preoperative viral load (HBV DNA <10(3) IU/mL vs. HBV DNA ≥10(3)) and prophylaxis regimens (HBIg vs HBIg and antivirals). RESULTS: On multivariate analysis, prophylaxis with HBIg alone, but not HBV-DNA levels was independently associated with poor survival, with a relative risk (RR) of death of 6.5 (95% CI 2.1-19.8, P = 0.001). The risk of HBV recurrence, in this small series, was also associated with monoprophylaxis with HBIg (RR 27, 95% CI 5.2-147.2, P < 0.0001), but not with HBV-DNA levels. CONCLUSIONS: When prophylaxis with HBIg and antiviral agents was administered, survival and HBV recurrence were not influenced by HBV-DNA levels determined by real time-PCR prior to OLT.

HBV core region variability: effect of antiviral treatments on main epitopic regions.

BACKGROUND: Amino acid (AA) changes in specific hepatitis B core antigen (HBcAg) regions were assessed in patients infected with chronic hepatitis B (CHB) after a 12-month untreated period and after receiving antiviral therapy (interferon, lamivudine or adefovir dipivoxil), and in inactive hepatitis B surface antigen-positive carriers. METHODS: Samples corresponding to different time points in 76 CHB cases (64 on-treatment) and 4 inactive carriers were included. The main precore mutation, T-helper immunodominant epitope at AA 50-69 (Th50-69), minor T-helper epitope (Th28-47), B-cell immunodominant epitope (B74-84) and a conserved region of HBcAg at AA 1-11 (AA1-11) were directly sequenced. For comparisons, the average number of AA changes in each region was standardized to 12 months (Av12). RESULTS: AA changes clustered mainly in immunodominant regions (69%). The highest percentage of cases (%n) with changes and highest Av12 changes were detected after interferon treatment (%n=73%, Av12=3.1 in Th50-69 and %n=86%, Av12=2.7 in B74-84). At baseline, immunodominant regions had higher Av12 changes in hepatitis B e antigen-negative patients and those with main precore mutations. Changes in the Th28-47 region were more frequent after nucleoside/nucleotide analogue treatment (40%) than before treatment (9%). Codons 74 and 77 were the most polymorphic, and the double change E64D-N67T was significantly observed. Codon 84 substitutions were mainly associated with interferon treatment (P=0.05). CONCLUSIONS: Natural and treatment-induced substitutions in HBV core protein, occurring especially with interferon treatment, were characterized. Some immune-stimulating activity related to the minor Th28-47 epitope might be associated with nucleoside/nucleotide analogues; this activity was also seen in inactive carriers.

Quantitative longitudinal evaluations of hepatitis delta virus RNA and hepatitis B virus DNA shows a dynamic, complex replicative profile in chronic hepatitis B and D.

BACKGROUND & AIMS: This study presents a real-time reverse-transcription PCR (rt-RT-PCR) assay for hepatitis delta virus (HDV) RNA quantification, designed to clarify the interplay between HDV and hepatitis B virus (HBV) in chronic infection. METHODS: Serum HDV-RNA and HBV-DNA were analysed by rt-RT-PCR in a cross-sectional study of 37 untreated chronic HDV patients, 25 of whom were also longitudinally studied. RESULTS: In the cross-sectional study, both viruses were active in 15 (40.5%) patients and inactive in 4 (10.8%); HDV alone was active in 12 (32.4%) and HBV in 6 (16.2%). The longitudinal study showed seven replication profiles, with considerable fluctuating activity of one or both viruses, including alternating predominance. In 20% of cases, longitudinal HBV/HDV viral loads differed from cross-sectional results, indicating a risk of misinterpreting HBV/HDV interactions when assessing a single determination. Fluctuating HBV replication only increased in the presence of fluctuating HDV activity. HBsAg levels, stable in HBV single infection, fluctuated in HDV chronic infection. The results of both the cross-sectional and longitudinal study call into question the major suppressor effect of HDV over HBV, revealing an important role of HBV. CONCLUSIONS: Longitudinal evaluation of viremia shows a complex interaction between HBV and HDV and is essential to understand the pathophysiology of chronic HDV infection.

Estudio de seroprevalencia de hepatitis B en deportistas de orientación / Seroprevalence study of hepatitis B among orienteers

Fundamento y objetivo: Detectar casos asintomáticos relacionados con un brote, valorar la seroprevalencia de hepatitis B (HB) en deportistas de orientación y establecer recomendaciones. Pacientes y método: Se realizó un estudio transversal de seroprevalencia entre 116 deportistas de orientación que habían competido en las categorías implicadas en un brote previo y una muestra estratificada de 166 corredores del resto de otras categorías de competición. Se analizaron marcadores de HB: antígeno de superficie del virus de la HB (VHB) (HBsAg), anticuerpo contra el antígeno core del VHB (anti-HBc), anticuerpos contra el HBsAg, anti-HBc tipo inmunoglobina M y antecedentes de vacunación. Los resultados se expresan utilizando pesos ponderados. Resultados: La seroprevalencia de HB (anti-HBc positivos) fue del 6,7% (n=12; intervalo de confianza [IC] del 95%: 0,6 a 12,9). No se observó ningún caso de HB aguda o crónica. Todos los marcadores fueron negativos para el 61,1% (n=64; IC del 95%: 46,3 a 75,6), y el 32,3% (n=29; IC del 95%: 18,2 a 46,4) tenía marcadores de inmunidad por vacunación. Entre los sujetos menores de 25 años, el 28,4% estaba sin vacunar a pesar de que entraban en el calendario vacunal. Conclusiones: Los resultados muestran que la seroprevalencia de HB entre deportistas de orientación no difiere de la población general. Sin embargo, es necesario reforzar la vacunación entre adolescentes y adultos jóvenes. Se dan recomendaciones generales para la prevención de HB a las federaciones de orientación (AU)

Background and objective: Our objectives were to detect asymptomatic cases involved in an outbreak of hepatitis B, to assess the seroprevalence of hepatitis B (HB) in orienteers and to establish recommendations. Patients and method: One hundred sixteen orienteers who had competed in the categories involved in the previous outbreak as well as a stratified random sample of 166 of the remaining orienteers in other competition categories were included in a cross-sectional serological prevalence study. HB surface antigen (anti-HBs); total antibody to HB core antigen (total anti-HBc); HB surface antigen (Ag HBs); and antibody IgM to HB core antigen (anti-HBcIgM) along with the history of vaccination for hepatitis B were analyzed. The results were weighted. Results: The seroprevalence of HB (total anti-HBc positive) was 6.7% (n=12, 95%CI 0.6-12.9). No case of acute HB or chronic infection was observed. All the serological markers were negative for 61.1% (n=64, 95%CI 46.3-75.6), and 31.5% (n=29, 95%CI 18.2-46.4) had markers of immunity due to vaccination. Among individuals under 25 years of age, 28.4% were unvaccinated, although they were covered by vaccination programs. Conclusion: Our results suggest that the seroprevalence of HB among orienteers is not different from the general population in Spain. However, it is necessary to reinforce the vaccination among adolescents and young adults. General recommendations for the prevention of HB were made to orienteering federations (AU)

[Seroprevalence study of hepatitis B among orienteers]. / Estudio de seroprevalencia de hepatitis B en deportistas de orientación.

BACKGROUND AND OBJECTIVE: Our objectives were to detect asymptomatic cases involved in an outbreak of hepatitis B, to assess the seroprevalence of hepatitis B (HB) in orienteers and to establish recommendations. PATIENTS AND METHOD: One hundred sixteen orienteers who had competed in the categories involved in the previous outbreak as well as a stratified random sample of 166 of the remaining orienteers in other competition categories were included in a cross-sectional serological prevalence study. HB surface antigen (anti-HBs); total antibody to HB core antigen (total anti-HBc); HB surface antigen (Ag HBs); and antibody IgM to HB core antigen (anti-HBcIgM) along with the history of vaccination for hepatitis B were analyzed. The results were weighted. RESULTS: The seroprevalence of HB (total anti-HBc positive) was 6.7% (n=12, 95% CI 0.6-12.9). No case of acute HB or chronic infection was observed. All the serological markers were negative for 61.1% (n=64, 95% CI 46.3-75.6), and 31.5% (n=29, 95% CI 18.2-46.4) had markers of immunity due to vaccination. Among individuals under 25 years of age, 28.4% were unvaccinated, although they were covered by vaccination programs. CONCLUSION: Our results suggest that the seroprevalence of HB among orienteers is not different from the general population in Spain. However, it is necessary to reinforce the vaccination among adolescents and young adults. General recommendations for the prevention of HB were made to orienteering federations.

Use of the novel INNO-LiPA line probe assay for detection of hepatitis B virus variants that confer resistance to entecavir therapy.

A line probe assay (INNO-LiPA DR, version 3) for the detection of hepatitis B virus mutations that confer resistance to entecavir therapy was evaluated. The INNO-LiPA DR assay is a highly sensitive assay that is easily applicable for the detection and monitoring of entecavir resistance-conferring mutations and is more sensitive than sequencing for the detection of mixed sequences.

[Molecular virology of the hepatitis B virus]. / Virología molecular del virus de la hepatitis B.

The hepatitis B virus (HBV) belongs to the hepadnavirus family. The genome of the virus, formed by a small DNA molecule with 3,200 base pairs, has 4 strongly overlapping protein coding regions: ORF preS/S, corresponding to the envelope proteins that constitute the HBV surface antigen (HBsAg); ORF preC/C, which encodes the viral capsid component (core antigen or HBcAg) and a non-structural protein that, after postranslation modification, is secreted and constitutes the "e" antigen (HBeAg); ORF P, which encodes the viral polymerase (polyprotein with DNA polymerase activity, reverse transcriptase and RNAase), and ORF X, which encodes a protein that acts as a multifunctional regulator for both the viral and cell cycles. HBV has a mutation rate of 1.4-3.2 x 105 substitutions/nucleotide/year. As a result of this variability, the virus circulates as a complex mixture of genetic variants, constituting a semi-species, that evolves throughout the infection depending on the evolutionary pressure of factors such as the immune response and antiviral treatments. Based on this variability, HBV has been classified into 8 genotypes (A-H) defined by a difference of more than 8% in the sequences of the complete viral genome. This variability is also responsible for HBV resistance to antiviral treatments with nucleotide and nucleoside analogs. Diagnosis of HBV infection includes determination of virological markers: viral antigens (HBsAg, HBeAg), specific antibodies (anti-HBc, anti-HBe, anti-HBs) and study of HBV-DNA for its detection and quantification and determination of genotypes and viral variants.

Analysis of hepatitis B genotype changes in chronic hepatitis B infection: Influence of antiviral therapy.

BACKGROUND/AIMS: The frequency of mixed hepatitis B virus (HBV) genotypes in chronic HBV (CHB) and genotype changes during natural disease evolution and as a result of antiviral therapy were investigated. METHODS: Serum samples from 103 CHB patients were included in a cross-sectional study. Longitudinal study of HBV genotypes was performed in 22 patients, 17 of them under antiviral therapy (lamivudine and/or adefovir). HBV genotyping was done by the INNO-LiPA HBV assay. RESULTS: Genotypes observed in the cross-sectional study: A 32% of cases, D 42%, C 2%, F 2%, and mixed genotypes 22% (mainly A/D, followed by A/G). Genotype G was found in 7% of patients, always combined with other genotypes. In the longitudinal study, genotype changes were observed only in treated patients (9 cases). Genotype A strains were positively selected in 6 of them, mainly as mixed A/D. In 6 patients, selection coincided with a decrease in HBV-DNA levels. CONCLUSIONS: A high frequency of mixed HBV genotypes was observed in our setting. Selection of genotype A strains during treatment is likely an indication that sensitivity to therapy differs between genotypes A and D. The absence of changes in untreated patients suggests that HBV genotype is stable without external factors.

Virología molecular del virus de la hepatitis B / Molecular virology of the hepatitis B virus

El virus de la hepatitis B (VHB) pertenece a la familia de los hepadnavirus. El genoma del virus, formado por una pequeña molécula de ADN de 3.200 pares de bases, consta de 4 regiones codificantes de proteínas (ORF) fuertemente solapadas: ORF preS/S, correspondiente a las proteínas de la envuelta que constituyen el antígeno de superficie del VHB (HBsAg); ORF preC/C, que codifica el componente de la cápside viral (antígeno core o HBcAg) y una proteína no estructural que tras su modificación postraduccional es secretada y constituye el denominado antígeno ®e» (HBeAg); ORF P, que codifica la polimerasa viral (poliproteína con actividad ADN polimerasa, transcriptasa reversa y ARN-asa) y la ORF X, que codifica una proteína que actúa como regulador multifuncional, tanto para el ciclo viral como para el celular. El VHB presenta una tasa de mutación de 1,4-3,2 105 sustituciones/nucleótido/año. Como consecuencia de esta variabilidad, el virus circula como una mezcla compleja de variantes genéticas, constituyendo una quasiespecie, que evoluciona a lo largo de la infección dependiendo de la presión evolutiva de factores como la respuesta inmunológica y los tratamientos antivirales. Sobre la base de esta variabilidad, el VHB se ha clasificado en 8 genotipos (A-H) definidos por una diferencia > 8% en las secuencias del genoma viral completo. Esta variabilidad es, además, la causante de la resistencia del VHB a los tratamientos antivirales con análogos de nucleótidos y nucleósidos. El diagnóstico de la infección por VHB incluye la determinación de marcadores virológicos: antígenos víricos (HBsAg, HBeAg), anticuerpos específicos (anti-HBc, anti-HBe, anti-HBs) y el estudio del ADN-VHB para su detección, cuantificación y determinación de genotipos y variantes víricas(AU)

The hepatitis B virus (HBV) belongs to the hepadnavirus family. The genome of the virus, formed by a small DNA molecule with 3,200 base pairs, has 4 strongly overlapping protein coding regions: ORF preS/S, corresponding to the envelope proteins that constitute the HBV surface antigen (HBsAg); ORF preC/C, which encodes the viral capsid component (core antigen or HBcAg) and a non-structural protein that, after postranslation modification, is secreted and constitutes the ®e» antigen (HBeAg); ORF P, which encodes the viral polymerase (polyprotein with DNA polymerase activity, reverse transcriptase and RNAase), and ORF X, which encodes a protein that acts as a multifunctional regulator for both the viral and cell cycles. HBV has a mutation rate of 1.4-3.2 x 105 substitutions/nucleotide/year. As a result of this variability, the virus circulates as a complex mixture of genetic variants, constituting a semi-species, that evolves throughout the infection depending on the evolutionary pressure of factors such as the immune response and antiviral treatments. Based on this variability, HBV has been classified into 8 genotypes (A-H) defined by a difference of more than 8% in the sequences of the complete viral genome. This variability is also responsible for HBV resistance to antiviral treatments with nucleotide and nucleoside analogs. Diagnosis of HBV infection includes determination of virological markers: viral antigens (HBsAg, HBeAg), specific antibodies (anti-HBc, anti-HBe, anti-HBs) and study of HBV-DNA for its detection and quantification and determination of genotypes and viral variants(AU)

Virología molecular del virus de la hepatitis B / Molecular virology of the hepatitis B virus

El virus de la hepatitis B (VHB) pertenece a la familia de los hepadnavirus. El genoma del virus, formado por una pequeña molécula de ADN de 3.200 pares de bases, consta de 4 regiones codificantes de proteínas (ORF) fuertemente solapadas: ORF preS/S, correspondiente a las proteínas de la envuelta que constituyen el antígeno de superficie del VHB (HBsAg); ORF preC/C, que codifica el componente de la cápside viral (antígeno core o HBcAg) y una proteína no estructural que tras su modificación postraduccional es secretada y constituye el denominado antígeno «e» (HBeAg); ORF P, que codifica la polimerasa viral (poliproteína con actividad ADN polimerasa, transcriptasa reversa y ARN-asa) y la ORF X, que codifica una proteína que actúa como regulador multifuncional, tanto para el ciclo viral como para el celular. El VHB presenta una tasa de mutación de 1,4-3,2 105 sustituciones/nucleótido/año. Como consecuencia de esta variabilidad, el virus circula como una mezcla compleja de variantes genéticas, constituyendo una quasiespecie, que evoluciona a lo largo de la infección dependiendo de la presión evolutiva de factores como la respuesta inmunológica y los tratamientos antivirales. Sobre la base de esta variabilidad, el VHB se ha clasificado en 8 genotipos (A-H) definidos por una diferencia > 8% en las secuencias del genoma viral completo. Esta variabilidad es, además, la causante de la resistencia del VHB a los tratamientos antivirales con análogos de nucleótidos y nucleósidos. El diagnóstico de la infección por VHB incluye la determinación de marcadores virológicos: antígenos víricos (HBsAg, HBeAg), anticuerpos específicos (anti-HBc, anti-HBe, anti-HBs) y el estudio del ADN-VHB para su detección, cuantificación y determinación de genotipos y variantes víricas

The hepatitis B virus (HBV) belongs to the hepadnavirus family. The genome of the virus, formed by a small DNA molecule with 3,200 base pairs, has 4 strongly overlapping protein coding regions: ORF preS/S, corresponding to the envelope proteins that constitute the HBV surface antigen (HBsAg); ORF preC/C, which encodes the viral capsid component (core antigen or HBcAg) and a non-structural protein that, after postranslation modification, is secreted and constitutes the «e» antigen (HBeAg); ORF P, which encodes the viral polymerase (polyprotein with DNA polymerase activity, reverse transcriptase and RNAase), and ORF X, which encodes a protein that acts as a multifunctional regulator for both the viral and cell cycles. HBV has a mutation rate of 1.4-3.2 x 105 substitutions/nucleotide/year. As a result of this variability, the virus circulates as a complex mixture of genetic variants, constituting a semi-species, that evolves throughout the infection depending on the evolutionary pressure of factors such as the immune response and antiviral treatments. Based on this variability, HBV has been classified into 8 genotypes (A-H) defined by a difference of more than 8% in the sequences of the complete viral genome. This variability is also responsible for HBV resistance to antiviral treatments with nucleotide and nucleoside analogs. Diagnosis of HBV infection includes determination of virological markers: viral antigens (HBsAg, HBeAg), specific antibodies (anti-HBc, anti-HBe, anti-HBs) and study of HBV-DNA for its detection and quantification and determination of genotypes and viral variants (AU)

Adefovir for chronic hepatitis B treatment: identification of virological markers linked to therapy response.

BACKGROUND: HBV variants rtA181V/T, rtN236T and rtl233V, which confer resistance to adefovir dipivoxil (ADV), are not detected in many non-responding patients. Virological characteristics useful for predicting response have not been clearly elucidated. We determined pretreatment virological markers to predict non-response and possible emergence of new variants during therapy. METHODS: This longitudinal study included 41 patients with chronic hepatitis B virus (HBV) infection receiving ADV monotherapy or ADV plus lamivudine (3TC). A fragment of HBV polymerase including catalytic domains was analysed for ADV-resistant variants. RESULTS: Complete virological response (CVR; HBV DNA < 2.5 log10 copies/ml) was observed in 15 (36.6%) patients and partial virological response (PVR; HBV DNA < 4 log, copies/ml) in 23 (56.1%) patients. On multivariate analyses, hepatitis B e antigen (HBeAg) status was independently associated with CVR (hazard ratio [HR] = 0.27, P = 0.002) and PVR (HR = 0.21, P < 0.001) and viral genotype with CVR (HR = 0.13, P = 0.01). Predictive values for HBeAg were 88% for PVR in HBeAg-negative and 79% for non-CVR in HBeAg-positive patients. Predictive values for viral genotype were 93% for non-CVR and 72% for non-PVR for genotype A. On sequencing, variant rt217R (associated with subgenotype A2) was predictive of non-CVR (100%) and non-PVR (72.7%); the rtS219A variant emerged during therapy in three non-PVR patients. Both positions are located in a region likely to be related to the substrate union site, as predicted by our structural model of the HBV polymerase. CONCLUSIONS: Virological pretreatment characteristics (HBeAg, viral genotype and rtL217R polymorphism) are potentially associated with ADV response. HBV polymerase structural modelling has provided a hypothesis to explain the molecular mechanism for ADV resistance associated with rtR217.

[Adefovir dipivoxil compassionate use program in Spain: efficacy and resistance analysis]. / Programa de uso compasivo con adefovir dipivoxil en España: valoración de su eficacia y estudio de las resistencias.

BACKGROUND AND OBJECTIVE: The extended treatment with lamivudine in patients with chronic hepatitis B is associated with the emergence of resistances. Patients with resistance to lamivudine show a loss of biochemical and virological responses and a higher progression of their liver disease. Adefovir dipivoxil, an analogue of the nucleotides, is effective for the treatment of patients with resistance to lamivudine. The aim of this study was to evaluate the efficacy, safety and resistance of adefovir dipivoxil in patients with chronic hepatitis B refractory to treatment with lamivudine. PATIENTS AND METHOD: One hundred and twenty hepatits B virus patients refractory to lamivudine were treated with adefovir dipivoxil. Seventy-four patients were followed up during two years. In all cases, the hepatitis B virus-DNA was determined by polymerase chain reaction, and in those cases without response to treatment, the presence of resistances to adefovir and lavimudine were studied. RESULTS: At the second year of treatment, we observed a biological response of 54.1%, a biochemical response of 62.2%, while an elimination of hepatitis B e antigen was seen in 21% cases. 20% patients developed resistance to adefovir dipivoxil, and the most frequent detected mutations were: A181V, A181T and N236T. Drug safety was excellent; in fact, only one adverse effect related to the drug was detected. CONCLUSIONS: Treatment with adefovir dipivoxil for 2 years in mono-therapy in patient who are previously non-responders to lavimudine is associated with a high biochemical and virologycal response with an excellent safety. At the second year of treatment, the adefovir dipivoxil resistance rate is 20%.

Programa de uso compasivo con adefovir dipivoxil en España: valoración de su eficacia y estudio de las resistencias / Adefovir dipivoxil compassionate use program in Spain: efficacy and resistance analysis

Fundamento y objetivo: El tratamiento prolongado con lamivudina de los pacientes con hepatitis B crónica se asocia a la emergencia de resistencias. Los pacientes con resistencia a la lamivudina presentan una pérdida de la respuesta tanto bioquímica como virológica y una mayor progresión de la enfermedad hepática. El adefovir dipivoxil, un análogo de los nucleótidos, es eficaz en el tratamiento de los pacientes con resistencia a la lamivudina. El objetivo de este estudio ha sido evaluar la eficacia, la seguridad y las resistencias del adefovir dipivoxil en pacientes con hepatitis B crónica refractarios al tratamiento con lamivudina. Pacientes y método: Se ha incluido a 120 pacientes afectados de hepatitis B crónica y refractarios al tratamiento con lamivudina que recibieron tratamiento con adefovir dipivoxil. En 74 de ellos se realizó seguimiento durante 2 años. En todos los casos se determinó el ADN del virus de la hepatitis B por reacción en cadena de la polimerasa, y en los casos sin respuesta al tratamiento se estudió la presencia de resistencias a adefovir dipivoxil y lamivudina. Resultados: A los 2 años de tratamiento se observó respuesta virológica en el 54,1% de los pacientes, respuesta bioquímica en el 62,2% y eliminación del antígeno e de la hepatitis B en el 21%. Se detectaron resistencias a adefovir dipivoxil en el 20% de los casos, y las mutaciones detectadas con mayor frecuencia fueron A181V, A181T y N236T. La seguridad del fármaco fue excelente, pues se detectó sólo un efecto adverso relacionado con el tratamiento. Conclusiones: El tratamiento durante 2 años con adefovir dipivoxil en monoterapia en pacientes previamente refractarios a lamivudina se asocia a una alta tasa de respuesta bioquímica y virológica, con una seguridad excelente. La tasa de resistencias al adefovir dipivoxil a los 2 años fue del 20%

Background and objective: The extended treatment with lamivudine in patients with chronic hepatitis B is associated with the emergence of resistances. Patients with resistance to lamivudine show a loss of biochemical and virological responses and a higher progression of their liver disease. Adefovir dipivoxil, an analogue of the nucleotides, is effective for the treatment of patients with resistance to lamivudine. The aim of this study was to evaluate the efficacy, safety and resistance of adefovir dipivoxil in patients with chronic hepatitis B refractory to treatment with lamivudine. Patients and method: One hundred and twenty hepatits B virus patients refractory to lamivudine were treated with adefovir dipivoxil. Seventy-four patients were followed up during two years. In all cases, the hepatitis B virus-DNA was determined by polymerase chain reaction, and in those cases without response to treatment, the presence of resistances to adefovir and lavimudine were studied. Results: At the second year of treatment, we observed a biological response of 54.1%, a biochemical response of 62.2%, while an elimination of hepatitis B e antigen was seen in 21% cases. 20% patients developed resistance to adefovir dipivoxil, and the most frequent detected mutations were: A181V, A181T and N236T. Drug safety was excellent; in fact, only one adverse effect related to the drug was detected. Conclusions: Treatment with adefovir dipivoxil for 2 years in mono-therapy in patient who are previously non-responders to lavimudine is associated with a high biochemical and virologycal response with an excellent safety. At the second year of treatment, the adefovir dipivoxil resistance rate is 20%