Maria-Cristina Navas

Worldwide genetic diversity of HBV genotypes and risk of hepatocellular carcinoma

Hepatitis B viruses (HBV) are responsible for over 50% of the worldwide attributable risk of hepatocellular carcinoma (HCC) and this figure increases even further in regions of high endemicity. Systematic sequencing of HBV genomes has identified that this common virus existed as eight distinct genotypes (denoted A-H), each regrouping variants with less than 8% divergence in their DNA sequence. These genotypes differ by their geographic distribution in populations around the globe. There is evidence that HBV genotypes also differ by their pathogenic properties, including their risk of persistence as chronic infection and their capacity to induce precursor disease or cancer. On the other hand, HBV genes may undergo mutations that become selected during the course of chronic infection and progressive liver disease. The most significant of these mutations in the context of HCC are those occurring in the pre-core (Pre-C) and basal core promoter (BCP) regions. These mutations may upregulate HBV expression and increase its virulence. These mutations may occur in all HBV genotypes but are more common in genotypes associated with more severe disease and cancer, in particular genotype C. Understanding the molecular basis of pathological variations between HBV variants is critical for prediction of disease severity. It will also be important to determine whether differences among genotypes may have an impact on the long-term protective efficacy of universal HBV vaccination.

Hepatitis C virus seroprevalence in multi-transfused patients in Colombia

BACKGROUND Hepatitis C Virus (HCV) infection is a public health problem worldwide, with particular relevance in multi-transfused patients given that HCV is principally transmitted by exposure to infected blood. STUDY DESIGN Between February and September 2003 a cross-sectional study was carried out in four hospital centres in Bogotá and Medellin, Colombia, to determine the risk factors for HCV infection in 500 multi-transfused patients. RESULTS The study population was distributed in five groups: haemophilia, haemodyalsis, acute bleeding, ontological illnesses and sickle cell disease or thalassemia. Serum samples from patients were tested for HCV antibodies (Asxym, Abbott). An overall prevalence (9.0%; 95% confidence interval (CI): 6.4-11.6) (45/500) of HCV infection was found. Anti-HCV antibodies were detected in 32.2% of patients with haemophilia, 6.1% of patients undergoing haemodialysis, 7.1% of patients with sickle cell disease or thalassemia, 2.6% of patients with acute bleeding and 3.4% of patients with ontological or hematological diseases. The main risk factors associated with infection by HCV were: to be hemophilic (odds ratio, OR = 18.03; 95% Cl: 3.96-114.17), having received transfusions before 1995 (OR = 12.27; 95% Cl: 5.57-27.69), and having received more than 48 units of blood components (OR = 6.08; 95% CI: 3.06-12.1). In the multivariate analysis, only the year of transfusions (before 1995) remained significantly associated with risk of infection by HCV. CONCLUSIONS The data show a 3-fold reduction in the infection risk between 1993 and 1995, when the serological screening for HCV in blood donors was being introduced. A reduction greater than 90% was achieved by 1995 when the screening coverage reached 99%.

Etiology and Viral Genotype in Patients with End-Stage Liver Diseases admitted to a Hepatology Unit in Colombia

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are the principal risk factor associated to end-stage liver diseases in the world. A study was carried out on end-stage liver disease cases admitted to an important hepatology unit in Medellin, the second largest city in Colombia. From 131 patients recruited in this prospective study, 71% of cases were diagnosed as cirrhosis, 12.2% as HCC, and 16.8% as cirrhosis and HCC. Regarding the risk factors of these patients, alcohol consumption was the most frequent (37.4%), followed by viral etiology (17.6%). Blood and/or hepatic tissue samples from patients with serological markers for HCV or HBV infection were characterized; on the basis of the phylogenetic analysis of HCV 5′ UTR and HBV S gene, isolates belonged to HCV/1 and HBV/F3, respectively. These results confirm the presence of strains associated with poor clinical outcome, in patients with liver disease in Colombia; additionally, HBV basal core promoter double mutant was identified in HCC cases. Here we show the first study of cirrhosis and/or HCC in Colombian and HBV and HCV molecular characterization of these patients. Viral aetiology was not the main risk factor in this cohort but alcohol consumption.

Analysis of the V3 loop sequences from 12 HIV type 1-infected patients from Colombia, South America.

1141 E IG HTEEN Y EA RS after the first report of infections by human immunodeficiency virus (HIV), the causative agent of AIDS, the virus continues to spread around the world. Nowadays the HIV epidem ic consists of multiple smaller epidemics, each with its own pattern of transmission routes and dynamic. In Latin America, it has been estimated that there are 1.4 million adults with HIV/AIDS infection. While the infection was present at a low level in the 1980s, most of the Latin American countries had well-established epidemics by 1997. This region can be classified in two groups on the basis of the adult prevalence rate (APR): the first group, with a prevalence between 0.5 and 2.0%, includes most of the countries, among them Brazil, Peru, Venezuela, Argentina, and Honduras; the second group has a prevalence between 0.13 and 0.5%, and includes Colombia, Mexico, Chile, Ecuador, and Nicaragua. Bolivia is the country that presents the lowest prevalence rate (0.0–0.03%). Furthermore, these values could be underestimated since in some countries the systematic surveillance system is limited.1,2 HIV-1 strains with widely divergent nucleotide sequences and biological properties have been isolated from different geographic regions. On the basis of phylogenetic sequence analyses of env and gag genes, HIV-1 can be divided into three groups: a major group M and two minor groups N and O. Group M can be further subdivided into 10 genetic subtypes designated A to J.3,4 The molecular characterization carried out in South America has shown that subtype B is prevalent, as it is in North America and Europe.5–7 In addition, subtypes F, C, D, and A have been reported in this region. Finally, some recom binant strains between subtypes B and F have been identified in Brazil and Argentina.9–12 The first case of AIDS in Colombia was described in 1983 and, since that time, 8433 cases of AIDS have been reported, a number likely to be underestimated. By the end of 1997, the World Health Organization (WHO, Geneva, Switzerland) has estimated in Colombia 72,000 adults, 15–49 years of age, with HIV infection (APR of 0.36% ).2 During the early phases of the epidemic in Colombia, HIV1 infection was common among homosexual men and blood product recipients. More than 10 years later, reported HIV infections are still associated with homosexual transmission in Bogota and the central–western region, but in the northeastern region some reports indicate an increase in heterosexual transmission.13 In this study, we describe the first HIV-1 sequences from Colombia, obtained from 12 asymptom atic patients. Between November 1993 and April 1995, a cross-sectional study was carried out to determine the prevalence and risk factors of HIV infection in a group of 434 men (58.3% ) and 310 women (41.7%) who participated in voluntary testing, and came from (1) two prisons, (2) the Public Laboratory for Sexually Transmitted Diseases (STD), (3) the harbor, and (4) a bar frequented by homosexual and bisexual men. The prevalence of HIV infection was 2.14% in the total population and (1) 2.5%, (2) 0.7%, (3) 0.5%, and (4) 12.3%, respectively. Only six blood samples from HIV-infected participants in this study (37.5% of positives) could be included in the molecular characterization of the C2V3 region of the env gene because of the inherent difficulties in getting samples, particularly from subjects in prisons and bars, and also because of technical problems in DNA extraction at the local laboratory. Six other blood samples from participants in a serosurvey test carried out by the Health Ministry in September 1994 were included (Table 1). Buffy coats were collected and frozen ( 2 80°C). DNA was extracted and polymerase chain reaction (PCRs) were carried out as described by Chaix et al..14 A fragment encoding the C2–V3 region of the env gene was sequenced and analyzed after cloning. Owing to the lack of amplification with V5–V3 primers in two cases (isolates 693 and 694), DNA was amplified with the ES7/ES8 primers before cloning.15 The sequencing reactions were carried out with the Prism Ready Reaction Amplitaq FS dye terminator (Perkin-Elmer, Norwalk, CT) on an automated DNA sequencer (Applied Biosystems 373A; Foster City, CA).

Molecular characterization of hepatitis c virus in multi-transfused Colombian patients

BackgroundHepatitis C virus (HCV) infects 170 million persons worldwide and is a public health problem. Considering that HCV is principally transmitted by exposure to infected blood, multi-transfused patients constitute one of the most important risk groups in developing countries. To explore the dynamics of this infection in Colombia, we performed a study to determine the genotypes of HCV in a cohort of multi-transfused patients.ResultsThe serum samples from patients positive for anti-HCV were evaluated for HCV RNA by nested-PCR of the 5’untranslated region (5’UTR). Viral genotype was determined by RFLP and/or automated sequencing. HCV subtype 1b was found in eight cases (66.7%) and subtype 1a in two cases (16.7%); seven isolates of subtype 1b were obtained from patients who had received the first transfusion before 1986. Either genotypes 2b (8.3%) or 3a (8.3%) were found in the remaining positive specimens.ConclusionsThis is the first HCV genotyping study developed in multi-transfused patients in Colombia where HCV subtype 1b was the most prevalent. The mutation G235A in the 5’UTR of three isolates generated an additional restriction site and an RFLP pattern different from those previously described for genotype 1.

Mutations in TP53 and CTNNB1 in Relation to Hepatitis B and C Infections in Hepatocellular Carcinomas from Thailand

Hepatocellular carcinoma (HCC) may develop according to two major pathways, one involving HBV infection and TP53 mutation and the other characterized by HCV infection and CTNNB1 mutation. We have investigated HBV/HCV infections and TP53/CTNNB1 mutations in 26 HCC patients from Thailand. HBV DNA (genotype B or C) was detected in 19 (73%) of the cases, including 5 occult infections and 3 coinfections with HCV. TP53 and CTNNB1 mutations were not mutually exclusive, and most of TP53 mutations were R249S, suggesting a significant impact of aflatoxin-induced mutagenesis in HCC development.

Occult Hepatitis B virus infection Among blood donors in Colombia

BackgroundHepatitis B virus (HBV) surface antigen (HBsAg) screening in blood banks reduced the risk of HBV transmission through transfusion. However, the detection of occult HBV infection among blood donors is imperative for improving blood safety. The aim of this study was to determine the frequency of occult hepatitis B virus infection among blood donors in Medellin, North West Colombia and to characterize the viral genotypes and mutations.MethodsSerum samples from blood donors with the serological profile HBsAg-/Anti-HBc+ were evaluated by nested or hemi-nested PCR for HBV genome ORF C, ORF S and ORF X. A pairwise analysis was carried out with deduced amino acids sequence of overlapping S/P region.ResultsA total of 302 serum samples HBsAg-/Anti-HBc+ from donors recruited in a blood bank in Medellin were evaluated by PCR for the HBV genome. Six samples (1.98%) were identified as occult HBV infection. The cases were confirmed by sequencing and viral load analysis. All HBV strains were genotype F, subgenotype F3. The amino acid substitutions sY100H, sV184A, and sK141N were detected in ORF S and rtL108P, rtR110G, rtL180M, rtR192C, rtT150S, and rtL187V in ORF P.ConclusionsThis is the first report and characterization of OBI cases in blood donors in Colombia. Six from 302 donors HBsAg-/Anti-HBc+ were identified. The mutations rtL108P, rtR110G, rtR192C, rtT150S and rtI187V were characterized for the first time in these samples. Further studies are necessary to explore if these mutations could potentially impair HBsAg production.

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.

Hepatitis B and Hepatitis C Infection Biomarkers and TP53 Mutations in Hepatocellular Carcinomas from Colombia

Hepatocellular Carcinoma (HCC) is a leading cause of cancer-related death worldwide. Globally, the most important HCC risk factors are Hepatitis B Virus (HBV) and/or Hepatitis C Virus (HCV), chronic alcoholism, and dietary exposure to aflatoxins. We have described the epidemiological pattern of 202 HCC samples obtained from Colombian patients. Additionally we investigated HBV/HCV infections and TP53 mutations in 49 of these HCC cases. HBV biomarkers were detected in 58.1% of the cases; HBV genotypes F and D were characterized in three of the samples. The HCV biomarker was detected in 37% of the samples while HBV/HCV coinfection was found in 19.2%. Among TP53 mutations, 10.5% occur at the common aflatoxin mutation hotspot, codon 249. No data regarding chronic alcoholism was available from the cases. In conclusion, in this first study of HCC and biomarkers in a Colombian population, the main HCC risk factor was HBV infection.

Hepatitis E Virus Genotype 3 in Colombia: Survey in Patients with Clinical Diagnosis of Viral Hepatitis.

Background Hepatitis E virus is a major cause of outbreaks as well as sporadic hepatitis cases worldwide. The epidemiology of this enterically transmitted infection differs between developing and developed countries. The aims of this study were to describe HEV infection in Colombian patients and to characterize the genotype. Methods A prospective study was carried out on 40 patients aged over 15 with a clinical diagnosis of viral hepatitis, recruited from five primary health units in the city of Medellin, Colombia. Fecal samples obtained from the 40 consecutives cases were analyzed for HEV RNA using nested reverse transcription PCR for both ORF1 and ORF2-3. The amplicons were sequenced for phylogenetic analyses. Results Nine (22.5%) cases of HEV infection were identified in the study population. Three HEV strains obtained from patients were classified as genotype 3. No significant association was found between cases of Hepatitis E and the variables water drinking source, garbage collection system and contact with pigs. Conclusions This is the first prospective study of hepatitis E in Colombian patients. The circulation of the genotype 3 in this population is predictable considering the reports of the region and the identification of this genotype from pigs in the state of Antioquia, of which Medellin is the capital. Further studies are necessary to establish whether zoonotic transmission of HEV is important in Colombia.