Strong association between genotype F and hepatitis B virus (HBV) e antigen-negative variants among HBV-infected argentinean blood donors

Hepatitis B virus in Mar del Plata, Argentina: Genomic characterization and evolutionary analysis of subgenotype F1b

The aim is to describe the molecular epidemiology and perform a genomic characterization of hepatitis B virus (HBV) circulating in Mar del Plata and to identify the origin and diversification patterns of the most prevalent genotype. The S gene and the region encompassing the X gene, basal core promoter (BCP), and precore (preC) was analyzed in 56 samples. They were genotyped as: 80% F1b, 9% A2, 7% D3, and 2% D1. A recombinant F4/D2 genome was detected. The double substitution G1764A/A1762T at the BCP (reduced HBeAg expression) was found in 20% F1b, 2% A2, 2% D1, and 2% D3 samples. A unique D3 presented the G1896A substitution at the preC (HBeAg negative phenotype). A 13% of the samples showed mutations at the HBsAg "a" immunodeterminant (escape from neutralizing antibodies). Mutations at the polymerase (antiviral resistance) were found in 52% of the samples. Coalescent analysis of subgenotype F1b, the most prevalent in the city, showed that viral diversification in Mar del Plata started by year 2000. F1b was the most prevalent genotype detected, being a characteristic of actual HBV infections in Mar del Plata. Local HBV exhibit clinically relevant mutations, but a minority of them was shown to be associated to potential vaccination escape or antiviral resistance. Nevertheless, further studies are needed to determine whether any of these mutants could pose a threat to prevention, diagnosis, or treatment.

Genetic variability of hepatitis B virus in Uruguay: D/F, A/F genotype recombinants

Hepatitis B virus (HBV) infection is a serious global health problem. Approximately 2 billion people worldwide have been infected, and approximately 350 million individuals currently suffer from HBV-induced chronic liver infection, which causes 600,000 deaths annually from chronic hepatitis, cirrhosis and hepatocellular carcinoma. HBV is classified in eight genotypes (A-H), and two more have been proposed (I-J). In this paper, complete genome sequences of nine Uruguayan HBV are reported. Five samples belong to genotype F1b and one to genotype A2. Three HBV recombinants were detected: A1/F1b, A2/F1b and D3/F1b. The following mutations were detected: a G1896A substitution, a 33-nucleotide deletion from position 2896 to 2928 in the Pre-S1 region involving Pre-S1 residues 3-13, a 33-nt deletion in the Pre-S1 region involving nt 2913-2945 and Pre-S1 residues 9-19. More F genotypes strains than expected were detected in this study, supporting the hypothesis that there are more people of indigenous origin than declared in our population. Also, one third of the samples analyzed were recombinants. This cannot be explained by the low HBV prevalence in Uruguay, but a high HBV infection rate in drug addicts and dialysis patients could act in favor of multiple-genotype HBV infections that could lead to recombination.

First hepatitis B virus full-length genomic study among blood donors from Argentina: unexpected mutations in the circulating subgenotypes' proteins

Hepatitis B virus (HBV) is a worldwide public health concern. The circulation of strains carrying mutations in the viral proteins implies both clinical and therapeutics challenges. HBV complete genomes (HBV-CGs) were reported from injecting drug users and HBV chronically infected patients from Argentina-including Amerindians-although no studies were conducted in blood donors. Here, we described HBV-CG sequences from the latter population. Some of the HBV sequences classified as B2 and C2 subgenotypes clustering together with Asian isolates, while others, such as D3, F1b, and F4, were homologous to European and Latin America sequences. New substitutions for all analyzed open reading frames and changes in the HBsAg hydrophobicity profiles were detected. Several HBV-CG subgenotypes are described for the first time in this population. Mutations observed in X, PreS, and P proteins have been associated with advanced liver disease, hepatocellular carcinoma, and/or natural resistance to nucleos(t)ide antiviral treatment. It deserves to be highlighted that these substitutions were detected in a population without epidemiological risk factors for viral infection, and most importantly, without any previous antiviral treatment (natural resistance). Regarding the remaining mutations, further research is warranted in order to determine their clinical and therapeutics relevance.

Molecular epidemiology of hepatitis B virus in Córdoba, Argentina

BACKGROUND

The analysis of the genomes of hepatitis B virus (HBV) identifies phylogenetic variants called genotypes, which may lead to distinct biological and clinical behaviors.

OBJECTIVES

The aim of this study was to describe the current molecular epidemiology and genetic diversity of HBV in Córdoba, Argentina.

STUDY DESIGN

A total of 52 HBV samples, 40 from HBV mono-infected and 12 from human immunodeficiency virus (HIV)-HBV co-infected patients, were sequenced in the S gene and in the basal core promoter-precore (BCP-pC) region.

RESULTS

Presence of subgenotypes F1b (35%) and F4 (17.5%), subgenotype A2 (37.5%), C (5.0%) (subgenotype could not be defined) and D (5.0%) (subgenotype D2, and the other could not be defined) were observed among mono-infected patients. The co-infected individuals displayed a different genotype distribution: sub-genotype A2 was the most common (75.0%), followed by subgenotype F1b (25.0%).

CONCLUSIONS

These results showed two epidemiologic scenarios: the mono-infected population may represent the ethnic composition of the current human population of Córdoba, where the Amerindian (genotype F) and European origins (subgenotype A2) account for the 90% of the samples; for the co-infected patients, the high prevalence of subgenotype A2 resemble previous analyses from Buenos Aires. In addition, mutations in hepatitis B surface antigen (HBsAg), polymerase and BCP-pC regions were identified, mainly in chronic or co-infected patients.

Molecular epidemiology and genetic diversity of hepatitis B virus in Mar del Plata city, Argentina

The aim of this work was to describe the current molecular epidemiology and genetic diversity of HBV in Mar del Plata, an important Argentinean touristic city. The phylogenetic analysis of 29 HBV DNA positive serum samples showed that F1b was the predominant subgenotype (sgt, 62.1%), followed by sgt A2 (13.8%) and sgt F4, gt D and gt G (6.9% each). Among anti-HBc IgM positive samples, 75.0% were sgt F1b, followed by sgt F4 (12.5%), sgt A2 (6.25%) and sgt D (6.25%). Three recombinant full length genomes were found: two G/F1b (some of the first gt G detected in Argentina) and one F4/D2. The circulation of clinical important mutations in the city was described. Mutations at the HBsAg were detected in 34.5% of the analyzed samples, associated with laboratory diagnosis and antiviral treatment failures, immune escape and hepatocellular carcinoma. Most of the samples presented wild type BCP/PC sequences. Coalescence analysis for the most prevalent sgt F1b estimated that the diversification mainly occured during mid '90s and the tMRCA was estimated in 1987. Finally, the high presence of the autochthonous sgt F1b, associated with the anti-HBc IgM positive infection and its present-day diversification process, shows the strong impact of internal human migratory movements into the current population of Mar del Plata.

Identification of novel recombinants of hepatitis B virus genotypes F and G in human immunodeficiency virus-positive patients from Argentina and Brazil

Hepatitis B virus (HBV) genotype G (HBV/G) infection is almost always detected along with a co-infecting HBV strain that can supply HBeAg, typically HBV/A2. In this study we describe, in two human immunodeficiency virus (HIV)-positive patients from Argentina and Brazil, the first report of HBV/G infection in Argentina and co-circulation of HBV/G, HBV/F and G/F recombinants in the American continent. HBV isolates carrying the 36 bp insertion of HBV/G were the most prevalent in both patients, with >99 % of colonies hybridizing to a probe specific for this insertion. Phylogenetic analyses of full-length genomes and precore/core fragments revealed that F4 and F1b were the co-infecting subgenotypes in the Brazilian and Argentinian patients, respectively. Bootscanning analysis provided evidence of recombination in several clones from both patients, with recombination breakpoints located mainly at the precore/core region. These data should encourage further investigations on the clinical implications of HBV/G recombinants in HBV/HIV co-infected patients.

Comparative analysis of hepatitis B virus genotype a molecular evolution in patients infected with HBV and in patients co-infected with HBV and HIV

HIV infection has a significant impact on the natural progression of liver disease caused by infection with hepatitis B virus (HBV), but its role in the molecular evolution of HBV is unknown. It is difficult to study the molecular evolution of HBV longitudinally considering its genomic complexity, which implies the analysis of paired samples. This study aimed to analyze the difference in the evolutionary dynamics of HBV among patients with HIV and uninfected individuals. In this study, 17 patients infected chronically with HBV were recruited, 9 of them were co-infected with HIV. Patients were HBe antigen-positive and infected with HBV genotype A. Paired plasma samples were collected from each patient 3 years apart, and they were compared subsequently to each other. The HBV phylogenetic inference among isolates from patients infected with HBV and co-infected with HBV and HIV tends to cluster separately. Likewise, when comparing the HBV evolutionary rate and genetic distances, values were higher in the former in both preC/C and S genomic regions. Intra-host analyses of HBV isolates revealed high diversity and complexity of quasispecies among patients infected with HBV exhibiting high numbers of viral variants and genetic distance. In summary, after studying the HBV molecular evolution among isolates ascribed to genotype A at inter- and intra-host levels, HBV exhibited low quasispecies complexity and diversity as well as low evolutionary rates in the presence of HIV co-infection, suggesting that the co-infection may have an impact on the HBV molecular evolution most likely from the weakened cellular immune response.

Hepatitis B virus in Buenos Aires, Argentina: genotypes, virological characteristics and clinical outcomes

Hepatitis B virus (HBV) is classified into eight major genotypes, A-H, which are geographically distributed worldwide. The aim of this work was to describe the clinical characteristics associated with the HBV genotypes circulating in Buenos Aires city. The study included 139 patients infected with HBV, whose clinical courses were classified as acute symptomatic self-limiting hepatitis, inactive carrier state and chronic active hepatitis (HBV e-antigen (HBeAg)-positive and HBeAg-negative). The HBV genotypes were determined in 128 patients by PCR-restriction fragment length polymorphism and phylogenetic analysis. Biochemical, virological, clinical and histological features were analysed. A differential distribution of genotypes between acute symptomatic and chronic infections was found. Among the acute cases, genotype F was predominant (65.2%, 30/46) and genotype D was rare (4.3%, 2/46), whereas among the chronic infections, a homogeneous distribution of genotypes A (26.8%, 22/82), D (31.7%, 26/82) and F (36.6%, 30/82), with an unusual presence of genotypes B (1.2%, 1/82) and C (3.7%, 3/82), was observed. Regarding the liver histology of chronically infected patients, genotype F tended to display higher histological activity indexes. Mutations related to HBV surface antigen immunoreactivity, antiviral resistance and HBeAg-negative status were studied. This work constitutes, to our knowledge, the first description of the clinical characteristics related to HBV genotypes in Argentina, where the distribution of genotypes in patients with acute infection has not been reported previously. Finally, it was established that genotype F is the prevalent genotype among the acute symptomatic infections in Buenos Aires city, and that it shows a tendency to cause an adverse disease outcome among the chronic cases.

Characterization of the basal core promoter and precore regions in anti-HBe-positive inactive carriers of hepatitis B virus

BACKGROUND

The study of hepatitis B virus (HBV) genomic heterogeneity has become a major issue in investigations aimed at understanding the relationship between HBV mutants and the wide spectrum of clinical and pathological conditions associated with HBV infection. Although most chronically infected HBV patients are inactive carriers, several virological aspects of this state remain unclear.

METHODS

In order to determine the prevalence and clinical significance of mutations in the basal core promoter (BCP) and precore (pC) regions among inactive carriers, the nucleotide sequences from 41 inactive carriers were analyzed and compared with those from 29 individuals with chronic active hepatitis.

RESULTS

Genotypes A (24.3%), D (37.1%), F1b (12.9%), and F4 (18.6%) were the most prevalent. Mutations in the BCP/pC regions were observed in most of the inactive carriers (92.7%) and in most of the patients with chronic active hepatitis (93.1%). The prevalence of mutation 1764(A) was significantly higher in patients with chronic active hepatitis (65.5%) than in inactive carriers (36.6%) (p=0.038), whereas the prevalences of mutations at the other positions analyzed were not significantly different. Older patients (>50 years) showed BCP/pC patterns with a higher number of substitutions. Mutations were found to be biased by genotype: the 1896(A) mutation was highly prevalent in genotypes D and F4, while alternative substitutions in the pC region were more prevalent in genotypes A and F1b.

CONCLUSIONS

Mutations in the BCP/pC regions are the hallmark of chronic anti-HBe-positive individuals; nevertheless, the even distribution of mutations in active and inactive carriers suggests that BCP/pC mutations may occur during HBV infection not strictly related to the HBV infection activity.

Geographical and genetic diversity of the human hepatitis B virus

Hepatitis B virus (HBV) is one of the most widely distributed viruses that infect humankind. Distinct clinical and virological characteristics of the HBV-infection have been reported in different geographical parts of the world and are increasingly associated with genetic diversity of the infecting virus. HBV is classified into genotypes and subgenotypes that are associated with ethnicity and geography. The genetic diversity of HBV in its various aspects has been the subject of extensive investigations during the last few decades. Since molecular epidemiology research tools have become widely available, the number of new publications in this field has grown exponentially. This review summarises the recent publications on the geographical distribution of genetic variants of HBV, and proposes updated criteria for the identification of new genotypes and subgenotypes of the virus.

Hepatitis B precore/core promoter mutations in isolates from HBV-monoinfected and HBV-HIV coinfected patients: a 3-yr prospective study

BACKGROUND

The course of chronic HBV infection is modified by HIV-coexistence.

OBJECTIVE

To analyze the role of HBV genomic heterogeneity in basal core promoter (BCP) and precore (Pc) genomic regions.

STUDY DESIGN

In a 3-yr prospective study, 39 HBV infected patients (20 monoinfected and 19 HIV-coinfected) were included. Eighty-two HBV isolates were studied at quasispecies level in the BCP/Pc genomic region. Clinical records obtained include data on lamivudine therapy and resistance mutations, HBV and HIV-viral load.

RESULTS

HBV isolates were predominantly ascribed to genotype (Gt) A2 among HBV-monoinfected and HIV-coinfected patients. BCP mutations in isolates from monoinfected patients were significantly more frequent than in those from coinfected ones, irrespective of the HBe expression pattern (p<0.0001). Regardless of the HIV-coexistence, the Pc mutation at G1896A only barely appeared among clone-derived sequences of GtF1 isolates, mainly from HBe(-) HBV-monoinfected patients.

CONCLUSIONS

HBV isolates characterized from HIV-coinfected patients seem to be more prone to exhibit a wild type genomic pattern at BCP regulatory region with respect to those from HBV-monoinfected ones. Besides, mutations at Pc region might be genotype-dependent in their frequency but not on HIV co-presence related.

Subgenotypes of hepatitis B virus genotype D (D1, D2, D3 and D5) in India: differential pattern of mutations, liver injury and occult HBV infection

Hepatitis B genotype D (HBV/D) is the most widespread genotype and exists as at least five subgenotypes (HBV/D1-D5). However, little is known about the association of virological characteristics with clinical differences among HBV/D subgenotypes. To investigate the virological characteristics of these subgenotypes and their clinical implications, we selected a cohort of 109 genotype D infected individuals from the state of West Bengal, India, including 68 HBsAg positive patients and 41 with occult HBV infection. Among the HBsAg positive subjects 28 had chronic hepatitis B virus infection, 40 were asymptomatic carriers based on clinical examination, liver function test and ultrasonograph results. Overall, HBV/D1 was found in 17%, HBV/D2 in 29%, HBV/D3 in 34% and HBV/D5 in 20% of the cases. HBV/D1 was significantly associated with chronic liver disease (P = 0.01), and in this subgenotype A1896 (PreC mutations) were most common. Although BCP mutations (A/C1753 and T1762/A1764) were found to be frequently associated with HBV/D2 (33% and 33%) and D5 (47% and 59%), no apparent clinical correlation was observed. On the other hand, occult HBV infection was significantly associated with HBV/D3 infection, along with low level of BCP and PreC mutations and several non-synonymous substitutions in the catalytic reverse transcriptase (RT) domain of polymerase gene. Similar nucleotide substitutions in the surface (S) gene region were observed from both northern and eastern Indian HBV/D3 isolates. In conclusion, HBV/D subgenotypes differ in their mutational patterns in the S, polymerase and the BCP/PreC regions that may influence their clinical outcomes.

Two simultaneous hepatitis B virus epidemics among injecting drug users and men who have sex with men in Buenos Aires, Argentina: characterization of the first D/A recombinant from the American continent

Previous studies have revealed that hepatitis B virus (HBV)/D and HBV/F predominate among blood donors from Buenos Aires, Argentina. In the present study, blood samples from two high-risk groups were analysed: 160 corresponding to street- and hospital-recruited injecting drug users [81.2% showing the 'anti-hepatitis B core antigen (anti-HBc) only' serological pattern] and 20 to hepatitis B surface antigen (HBsAg)(+)/anti-HBc(+) men who have sex with men. HBV genotypes were assigned by polymerase chain reaction amplification followed by restriction fragment length polymorphism and confirmed by nucleotide sequencing of two different coding regions. HBV DNA was detected in 27 injecting drug users (16.9%, occult infection prevalence: 7.7%), and 14 men who have sex with men (70%). HBV/A prevailed among injecting drug users (81.8%) while HBV/F was predominant among men who have sex with men (57.1%). The high predominance of HBV/A among injecting drug users is in sharp contrast to its low prevalence among blood donors (P = 0.0006) and men who have sex with men (P = 0.0137). Interestingly, all HBV/A S gene sequences obtained from street-recruited injecting drug users encoded the rare serotype ayw1 and failed to cluster within any of the known A subgenotypes. Moreover, one of the HBV strains from a hospital-recruited injecting drug user was fully sequenced and found to be the first completely characterized D/A recombinant genome from the American continent. Data suggest that two simultaneous and independent HBV epidemics took place in Buenos Aires: one spreading among injecting drug users and another one sexually transmitted among the homosexual and heterosexual population.

A new clade of hepatitis B virus subgenotype F1 from Peru with unusual properties

There are eight genotypes A-H of hepatitis B virus (HBV). Most genotypes are further divided into subgenotypes. Genotypes and subgenotypes influence the natural course of infection and therapy. We analysed nine sera from HBV carriers from Peru. Using the small hepatitis B surface protein HBs, all samples could be grouped to genotype F. Sequencing of three complete Peruvian genomes showed that HBV from Peru belongs to subgenotype F1. Two of the genomes from HBeAg positive carriers coded surprisingly for a stop codon in the polymerase-ORF leading to a translational stop after 213 and 214 aa, respectively. The third isolate from an HBe Ag positive carrier had three deletions: aa 1-53 and aa 111-142 in preS. In addition nt. 2002-2087 in the HBc-ORF were deleted, leading to an HBc starting at aa 66.

Hepatitis B virus genotypes circulating in Brazil: molecular characterization of genotype F isolates

Background

Hepatitis B virus (HBV) isolates have been classified in eight genotypes, A to H, which exhibit distinct geographical distributions. Genotypes A, D and F are predominant in Brazil, a country formed by a miscegenated population, where the proportion of individuals from Caucasian, Amerindian and African origins varies by region. Genotype F, which is the most divergent, is considered indigenous to the Americas. A systematic molecular characterization of HBV isolates from different parts of the world would be invaluable in establishing HBV evolutionary origins and dispersion patterns. A large-scale study is needed to map the region-by-region distribution of the HBV genotypes in Brazil.

Results

Genotyping by PCR-RFLP of 303 HBV isolates from HBsAg-positive blood donors showed that at least two of the three genotypes, A, D, and F, co-circulate in each of the five geographic regions of Brazil. No other genotypes were identified. Overall, genotype A was most prevalent (48.5%), and most of these isolates were classified as subgenotype A1 (138/153; 90.2%). Genotype D was the most common genotype in the South (84.2%) and Central (47.6%) regions. The prevalence of genotype F was low (13%) countrywide. Nucleotide sequencing of the S gene and a phylogenetic analysis of 32 HBV genotype F isolates showed that a great majority (28/32; 87.5%) belonged to subgenotype F2, cluster II. The deduced serotype of 31 of 32 F isolates was adw4. The remaining isolate showed a leucine-to-isoleucine substitution at position 127.

Conclusion

The presence of genotypes A, D and F, and the absence of other genotypes in a large cohort of HBV infected individuals may reflect the ethnic origins of the Brazilian population. The high prevalence of isolates from subgenotype A1 (of African origin) indicates that the African influx during the colonial slavery period had a major impact on the circulation of HBV genotype A currently found in Brazil. Although most genotype F isolates belonged to cluster II, the presence of some isolates belonging to clusters I (subgroup Ib) and IV suggests the existence of two or more founder viral populations of genotype F in Brazil.

Epidemiology of hepatitis virus B and C

Hepatitis B and C virus infections constitute a significant health problem in Latin America. Approximately 400,000 new cases of hepatitis B per year and 10 million people infected with hepatitis C are estimated to occur. HBV and HCV genotype distribution may reflect the different patterns of migration to the Americas: Genotype F and H of HBV correspond to the Amerindian genotype. Overall, Genotype 1 is the most prevalent HCV genotype in the Caribbean and in South and Central America. Hepatitis B and C epidemiology needs to be considered in the context of dissimilar social and economic aspects among the countries of the region. Behaviors, cultural and ethical aspects, as well as environmental and organizational processes affect directly the way these diseases are approached in their diagnosis, treatment and prevention.

Chronic hepatitis B: a global health problem requiring coherent worldwide treatment strategies

Chronic hepatitis B virus infection, a major cause of end-stage liver disease and hepatocellular carcinoma, is a worldwide health concern. While the past two decades have brought major advances in the availability of treatments to help delay or prevent these outcomes, treatment of chronic hepatitis B remains a serious challenge, not least due to the ability of the virus to remain in hepatocyte nuclei as a source of potential reactivation-hence the term chronic hepatitis B infection. This article reviews the current treatments available and suggests a framework for a rational approach to managing the disease.

Hepatitis B virus genotype distribution and its lamivudine-resistant mutants in HIV-coinfected patients with chronic and occult hepatitis B

Hepatitis B virus (HBV) genotypes were examined in HIV-infected patients with chronic and occult HBV infection. From a total population of 593 HIV-infected patients, 22 individuals (prevalence 3.7%) were found to be HBsAg while 72 (12.1%) were found to be anti-HBc alone. From them, 20 and 4 were HBV DNA positive, respectively. These last four patients are therefore considered to be HBV infected in an occult form. The genotypes could be determined in all 24 HBV-infected patients. HBV-A was the most common (20/24; 83.3%), followed by HBV-D (2/24; 8.3%) and HBV-F (1/24; 4.2%). The remaining sample exhibited mixed infection involving genotypes A and D as pure ones, thus also forming part of three intergenotypic recombinant forms exhibiting different mosaic S gene patterns. The sexual route of transmission was predominant among HBV genotype A-infected patients. Among the 24 HBV DNA-positive patients, point mutations related to lamivudine resistance were found in four strains. These viral strains showed a methionine-to-valine substitution at codon 204 (rtM204V) in association with an upstream B-domain change at rtL180M. Additionally, two of them exhibited the additional rtV173L mutation. The value of HBV molecular monitoring including both HBV viral genomic characterization and genotypic resistance profile in HIV-HBV-coinfected individuals is discussed.

Advances in the researches on hepatitis B virus genotyping and its clinical significance

The genotyping of hepatitis B virus (HBV) is a highlight of the studies associated with chronic hepatitis B inside and outside the country nowadays. HBV infection can lead to chronic carriage of the virus and progressive liver disease, including liver cirrhosis and hepatocellular carcinoma. The serological heterogeneity of HBsAg has been well established. HBV isolates have been classified into 10 different subtypes according to the antigenic determinants of their HBsAg. However, the classification of HBV by serologic subtyping is not rational because a single point mutation at the S gene may result in a change in subtype. Therefore, worldwide HBV isolates have been classified into eight genotypes: A, B, C, D, E, F, G and H, based on the comparison of complete HBV genomes, which is the gold standard for genotyping. The eight genotypes have a distinct characteristic geographical distribution and an HBV genotypic difference in HBV pathogenicity. It has been reported that there are remarkable differences in the clinical and virologic characteristics between the patients with different genotypes. Studies have revealed the association of HBV genotypes with the severity and outcome of chronic liver disease, but the results including the influence of genotypes on therapeutic responses are not consistent.

Hepatitis B virus genetic diversity in Latin America

Hepatitis B virus (HBV) infection is still a significant health concern in Latin America, where around 11 million persons are infected. Amerindian populations exhibit the highest prevalences of infection in the region. HBV exhibits a degree of variability intermediate between DNA and RNA viruses. This plasticity leads to the generation of several mutants and genotypic variability. Eight HBV genotypes (A-H) have been described, based on a minimum divergence of 8% of the complete genome sequences. HBV genotype F is the most divergent of the HBV genotypes, is autochthonous to South America and is highly predominant in the Northern region of South America. The recently described HBV genotype H is closely related to genotype F and seems to be restricted to Central and North America. Recombination among different HBV strains seems to be frequent, although it has not been described yet between American genotypes. Inside HBV genotype F, four subgenotypes have been described, which exhibit a geographic pattern of distribution. The clinical and biologic importance of the genotypic diversity of HBV is of major concern at the present moment and has been studied in Asia and Europe. In contrast, it is not known whether infection with the American HBV genotypes F and H is associated with a rapid or slow development of disease. The origin of HBV is still an open question. Depending on the model used for the phylogenetic analysis, an Asian or an American origin of HBV has been proposed. By revisiting the genotypic diversity of HBV, an alternative explanation is that human HBV genotypes might have emerged by several zoonotic introductions, both in the Old and the New World.

Detection of hepatitis B virus (HBV) genotype E carried--even in the presence of high titers of anti-HBs antibodies--by an Argentinean patient of African descent who had received vaccination against HBV

Genotype E hepatitis B virus (HBV) was detected in two Argentine sisters exhibiting an African mitochondrial lineage. One of them (who had been vaccinated against HBV) exhibited anti-HBs cocirculating antibodies without HBsAg escape mutants, while her unvaccinated sister showed a D144A HBsAg escape mutant without anti-HBs antibodies. Both sisters carried an unusual L209V substitution within HBsAg.

Dynamics of a hepatitis B virus e antigen minus population ascribed to genotype F during the course of a chronic infection despite the presence of anti-HBs antibodies

The in vivo evolution of genotype F HBV variants was recorded in a chronically infected patient throughout a 3-year observation period. Fluctuating levels of HBs Ag and anti-HBs antibodies were recorded, both of them cocirculating in peripheral blood samples at given times. Fifty S gene derived clones were sequenced and phylogenetically analyzed. As expected, some amino acid replacements within the S ORF were also observed within the P ORF while others were silent for the former. Such change was statistically significant for both S and P overlapping genes, which clearly indicates the appearance of a positive selection pressure. Supporting this notion, amino acid replacements were documented at both B and T cell epitopes in samples from 1997 and 1998. Several mutations were documented within and outside the "a" determinant in the major hydrophilic region. Such substitutions might have resulted from the attempt of HBV to evade both humoral and/or cellular immune response. To the best of our knowledge this unusual profile of HBV variants in presence of usually "neutralizing" anti-HBs antibodies was examined in vivo for the first time.

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Molecular epidemiology of hepatitis B virus in Latin America

Hepatitis B virus (HBV) is an etiological agent of acute and chronic liver disease existing throughout the world. The high genetic variability of HBV is reflected by eight genotypes (A to H), each one with a particular geographical prevalence. The global pattern of HBV genotypes is associated with the distribution of human populations among the different continents and may reflect the patterns of human migrations. Genotypes F and H are considered indigenous to Latin America. The most prevalent genetic group of Central and South America, genotype F, is subdivided into two subtypes and five clusters associated with defined geographic areas. Genotype H has been described in Mexico and Central America. This pattern provides a tool to reconstruct the initial immigration of ancestral Amerindians from Asia and their further spread through Central and South America. Other HBV genotypes found in different Latin American countries may reflect migration from other geographical areas into the region. Genotypes A and D are the signature of the European colonization that started in the sixteenth century, including slave trade from Africa. Genotypes B and C indicate the arrival of people from Southeast Asia. The impact of HBV genotypes on the natural course of HBV infection and response to treatment has been studied recently and controversial results have been obtained. The majority of the current information concerns with genotypes B and C. In contrast, very few data are available on the Latin American HBV genotypes F and H. It has been reported that liver failure and death may be more frequent in patients infected with genotype F. More studies are needed to assess the association between H13V genotypes and clinical course of infection, especially in Latin America.

Correlations of HBV genotypes, mutations affecting HBeAg expression and HBeAg/ anti-HBe status in HBV carriers

This study was carried out to determine the effects of hepatitis B virus genotypes, core promoter mutations (A1762G1764-->T1762A1764) as well as precore stop codon mutations (TGG-->TAG) on HBeAg expression and HBeAg/ anti-HBe status. Study was also performed on the effects of codon 15 variants (C1858/ T1858) on the predisposition of precore stop codon mutations (TGG-->TAG). A total of 77 sera samples were analyzed. Fifty one samples were successfully genotyped of which the predominant genotype was genotype B (29/ 51, 56.9 %), followed by genotype C (16/ 51, 31.4 %). Co-infections by genotypes B and C were observed in four samples (7.8 %). To a lesser degree, genotypes D and E (2.0 % each) were also observed. For core promoter mutations, the prevalence was 68.8 % (53/ 77) for A1762G1764 wild-type and 14.3 % (11/ 77) for T1762A1764 mutant while 9.1 % (7/ 77) was co-infected by both strains. The prevalence of codon 15 variants was found to be 42.9 % (33/ 77) for T1858 variant and 16.9 % (13/ 77) for C1858 variant. No TAG mutation was found. In our study, no associations were found between genotypes (B and C) and core promoter mutations as well as codon 15 variants. Also no correlation was observed between HBeAg/ anti-HBe status with genotypes (B and C) and core promoter mutations.

Genomic characterization of HBV genotype F in Bolivia: genotype F subgenotypes correlate with geographic distribution and T(1858) variant

Hepatitis B virus (HBV) strains were classified into eight genotypes from A to H. Genotype F, an indigenous genotype in Central and South America, has been classified into subgenotypes. An in-depth phylogenetic analysis was performed using two full-length Bolivian HBV sequences and other genotype F strains from the database. A novel nomenclature of subgenotypes of genotype F was proposed, in which Bolivia strains belonged to subgenotype F4. This subgenotype had both Leu(45) and Ile(110) in the S gene, and linked to the T(1858) in the precore. This novel nomenclature demonstrated the relation between variability of the HBV genome and the restricted geographical distribution of the virus in some parts of Central and South America.