Seroprevalence of hepatitis A virus among people born before and after implementation of universal vaccination in Argentina.

Background: Until 2005, when a single dose of vaccine was implemented in one-year-old children, the Hepatitis A virus (HAV) was responsible for approximately 90% of acute hepatitis cases in the paediatric population in Argentina. However, despite vaccination success, sporadic outbreaks of HAV still occur among adults. This study aimed to assess the seroepidemiology of HAV in Argentina, analysing IgG and IgM antibodies against HAV in a large population, both vaccinated and unvaccinated.

Impact of core protein naturally selected mutants associated with HBeAg-negative status in HBV biosynthesis.

Hepatitis B e antigen (HBeAg) loss represents a late stage of chronic hepatitis B virus (HBV) infection associated with a drastic decrease in HBV-DNA, a lower risk of disease progression, and the occurrence of several mutations in the preCore/core region. However, the underlying mechanisms supporting the downregulation of viral replication have yet to be elucidated. In the present study, the analysis of the frequency of subgenotype D1 core protein (HBc) mutations associated with HBeAg status revealed a higher mutation rate in HBeAg-negative sequences compared to HBeAg-positive ones.

Insights into induction of the immune response by the hepatitis B vaccine.

After more than four decades of hepatitis B virus (HBV) vaccine implementation, its safety and efficacy in preventing HBV infection have been proven and several milestones have been achieved. Most countries have included HBV immunization schedules in their health policies and progress has been made regarding universalization of the first HBV vaccine dose at birth. All of these actions have significantly contributed to reducing both the incidence of HBV infection and its related complications.

Molecular and biological characterization of hepatitis B virus subgenotype F1b clusters: Unraveling its role in hepatocarcinogenesis.

Hepatitis B virus (HBV) subgenotype F1b infection has been associated with the early occurrence of hepatocellular carcinoma in chronically infected patients from Alaska and Peru. In Argentina, however, despite the high prevalence of subgenotype F1b infection, this relationship has not been described. To unravel the observed differences in the progression of the infection, an in-depth molecular and biological characterization of the subgenotype F1b was performed.

Biological Characterization of Hepatitis B virus Genotypes: Their Role in Viral Replication and Antigen Expression.

Hepatitis B virus (HBV) inter-host evolution has resulted in genomic diversification reflected in the existence of nine genotypes (A-I) and numerous subgenotypes. There is growing evidence that genotypes influence HBV natural history, clinical outcomes, and treatment response. However, the biological characteristics underlying these differences have not yet been established.

Hepatitis C virus treatment failure: Clinical utility for testing resistance-associated substitutions.

The hepatitis C virus has a high mutation capacity that leads to the emergence of resistance-associated substitutions (RAS). However, the consequence of resistance selection during new direct-acting antiviral drug (DAA) treatment is not necessarily the therapeutic failure. In fact, DAA treatment has shown a high rate (> 95%) of sustained virological response even when high baseline RAS prevalence has been reported.

Viral hepatitis update: Progress and perspectives.

Viral hepatitis, secondary to infection with hepatitis A, B, C, D, and E viruses, are a major public health problem and an important cause of morbidity and mortality. Despite the huge medical advances achieved in recent years, there are still points of conflict concerning the pathogenesis, immune response, development of new and more effective vaccines, therapies, and treatment. This review focuses on the most important research topics that deal with issues that are currently being solved, those that remain to be solved, and future research directions.

Evolutionary analysis of SARS-CoV-2 spike protein for its different clades.

The spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become the main target for antiviral and vaccine development. Despite its relevance, e information is scarse about its evolutionary traces. The aim of this study was to investigate the diversification patterns of the spike for each clade of SARS-CoV-2 through different approaches.

Seroprevalence of hepatitis B, hepatitis C and HIV infection among patients undergoing haemodialysis in Buenos Aires, Argentina.

Blood-borne infections are a major cause of harm in individuals on haemodialysis (HD). In particular, knowledge about hepatitis B (HBV), hepatitis C (HCV) and human immunodeficiency virus (HIV) status in HD patients is a major concern, since these infections may cause comorbidities in this setting. There is a paucity of data regarding this issue in Argentina.

Phylogenetic analysis of SARS-CoV-2 in the first few months since its emergence.

During the first few months of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) evolution in a new host, contrasting hypotheses have been proposed about the way the virus has evolved and diversified worldwide. The aim of this study was to perform a comprehensive evolutionary analysis to describe the human outbreak and the evolutionary rate of different genomic regions of SARS-CoV-2. The molecular evolution in nine genomic regions of SARS-CoV-2 was analyzed using three different approaches: phylogenetic signal assessment, emergence of amino acid substitutions, and Bayesian evolutionary rate estimation in eight successive fortnights since the virus emergence.

Seroprevalence of hepatitis E virus in Argentinean blood donors.

Background: Hepatitis E virus (HEV) is the main cause of enteric acute viral hepatitis worldwide. In this epidemiological framework, it has become a threat to blood safety and a relevant issue for blood transfusions. However, there is a paucity of data regarding prevalence of HEV infection.

Hepatitis B surface antibodies seroprevalence among people born before and after implementation of universal HBV vaccination.

Universal vaccination is the most effective strategy to control hepatitis B virus (HBV) infection. In Argentina, vaccination against HBV was incorporated in year 2000 for newborns and in 2003 for 11 years old children. However, there is a paucity of data about protection levels against HBV infection.

Hepatitis B Virus X Gene Differentially Modulates Subgenotype F1b and F4 Replication.

Hepatitis B virus (HBV) is classified into ten genotypes and numerous subgenotypes (sgt). In particular, sgt F1b and sgt F4, native of Latin America, have been associated with differences in clinical and virological characteristics. Hepatitis B virus X protein (HBx) is a multifunctional regulatory protein associated with the modulation of viral transcription and replication.

Molecular epidemiology of hepatitis B virus mutants associated with vaccine escape, drug resistance and diagnosis failure.

The massive implementation of the vaccine and antiviral agents against hepatitis B virus (HBV), targeting the envelope and viral polymerase genes, induces a selection pressure that might lead to the emergence of variants that impair the effectiveness of the vaccine, diagnostic methods and antiviral therapy. The aim of this study was to evaluate the prevalence of HBV vaccine escape mutants (VEMs), diagnostic failure mutants (DFMs) and treatment resistance mutants (ARMs) among individuals from Buenos Aires, Argentina. HBV surface antigen and polymerase sequences obtained from serum samples of 530 HBV-infected individuals were analysed.

Analysis of fitness differences of hepatitis B virus genotypes D and F using a cotransfection assay.

Hepatitis B virus (HBV) circulates as a collection of genetically related variants that evolve throughout the chronic infection. Those viral variants that have the greatest fitness are fixed. We recently showed different fitness for HBV variants involved in two epidemiological situations.

HBV subgenotypes F1b and F4 replication induces an incomplete autophagic process in hepatocytes: Role of BCP and preCore mutations.

Hepatitis B virus (HBV) genotypes and mutants have been associated with differences in clinical and virological characteristics. Autophagy is a cellular process that degrades long-lived proteins and damaged organelles. Viruses have evolved mechanisms to alter this process to survive in host cells.

Human hepatocytes apoptosis induced by replication of hepatitis B virus subgenotypes F1b and F4: Role of basal core promoter and preCore mutations.

In the context of pathogenesis of HBV infection, HBV genotypes and mutants have been shown to affect the natural course of chronic infection and treatment outcomes. In this work, we studied the induction of apoptosis by the replication of HBV subgenotypes F1b and F4, and the naturally occurring mutants BCP and preCore. Both subgenotypes F1b and F4 HBV genome transfections induced cell death by apoptosis in human hepatocytes.

HBV DNA genome co-transfection procedure for the evaluation of relative fitness.

Hepatitis B virus (HBV) has a high mutation rate and exists as a mixture of genetically different but closely related variants. We present a HBV DNA co-transfection fitness assay and use it to evaluate the relative fitness of different HBV variants in two scenarios: seroconversion process and occupation of an ecological niche. In the seroconversion experiment, subgenotype D1 (sgtD1) deletion (1763-1770) had significantly lower fitness comparing with both sgtD1 wild type and sgtD1mut G1896A, while, in the case of occupation of ecological niche experiment, the results showed the same relative fitness between all of the genotype combinations, except F1b-F4.

Analysis of the Molecular Evolution of Hepatitis B Virus Genotypes in Symptomatic Acute Infections in Argentina.

Hepatitis B virus (HBV) is a globally distributed human pathogen that leads to both self-limited and chronic infections. At least eight genotypes (A-H) with distinct geographical allocations and phylodynamic behaviors have been described. They differ substantially in many virological and probably some clinical parameters.

Molecular epidemiology of hepatitis B virus in Misiones, Argentina.

Hepatitis B virus (HBV) infection is a major public health problem worldwide. The aims of this study were to describe the molecular epidemiology of HBV in the Province of Misiones, Argentina and estimate the phylodynamic of the main groups in a Bayesian coalescent framework. To this end, partial or complete genome sequences were obtained from 52 blood donor candidates.

Compartmentalization of hepatitis C virus variants in patients with hepatocellular carcinoma.

Chronic Hepatitis C Virus (HCV) infection is a major risk for hepatocellular carcinoma (HCC) development. HCV Core protein has been associated with the modulation of potentially oncogenic cellular processes and E2 protein has been useful in evolutive studies to analyze the diversity of HCV. Thus, the aim of this study was to evaluate HCV compartmentalization in tumoral, non-tumoral liver tissue and serum and to identify viral mutations potentially involved in carcinogenesis.

Identification of a new clade of hepatitis B virus genotype F.

Hepatitis B virus (HBV) is classified into eight main genotypes (A-H) and several subgenotypes. Here, three new genotype F complete genome sequences isolated from patients from Buenos Aires city are reported. The new sequences form a separate monophyletic group from the previously known subgenotype F4 strains.

Prevalence and trends of markers of hepatitis B virus, hepatitis C virus and human Immunodeficiency virus in Argentine blood donors.

Background: Transfusion-transmitted infections are a major problem associated with blood transfusion. The aim of this study was to determine prevalence and trends of HBV, HCV and HIV in blood donors in Argentina.

Methods: A retrospective study was carried out in blood donors of 27 transfusion centers covering the whole country over a period of eight years (2004-2011).