High prevalence of HBV/A1 subgenotype in native south Americans may be explained by recent economic developments in the Amazon.

Native American populations present the highest prevalence of Hepatitis B Virus (HBV) infection in the Americas, which may be associated to severe disease outcomes. Ten HBV genotypes (A­J) have been described, displaying a remarkable geographic structure, which most likely reflects historic patterns of human migrations. In this study, we characterize the HBV strains circulating in a historical sample of Native South Americans to characterize the historical viral dynamics in this population. The sample consisted of 1070 individuals belonging to 38 populations collected between 1965 and 1997. Presence of HBV DNA was checked by quantitative real-time PCR, and determination of HBV genotypes and subgenotypes was performed through sequencing and phylogenetic analysis of a fragment including part of HBsAg and Pol coding regions (S/Pol). A Bayesian Skyline Plot analysis was performed to compare the viral population dynamics of HBV/A1 strains found in Native Americans and in the general Brazilian population. A total of 109 individuals were positive for HBV DNA (~ 10%), and 70 samples were successfully sequenced and genotyped. Subgenotype A1 (HBV/A1), related to African populations and the African slave trade, was the most prevalent (66­94%). The Skyline Plot analysis showed a marked population expansion of HBV/A1 in Native Americans occurring more recently (1945­1965) than in the general Brazilian population. Our results suggest that historic processes that contributed to formation of HBV/A1 circulating in Native American are related with more recent migratory waves towards the Amazon basin, which generated a different viral dynamics in this region.

Resistance mutations are rare among protease inhibitor treatment-naive hepatitis C genotype-1 patients with or without HIV coinfection.

BACKGROUND: HCV has a high replication rate and a lack of proofreading activity, leading to a greatly diverse viral population. This diversity may lead to emergence of resistant strains in direct-acting antiviral therapy. The frequency of naturally occurring HCV protease inhibitor (PI) mutations has been addressed in many countries, but there are few data on the prevalence of these mutations in Brazilian patients. METHODS: We evaluated the sequence of HCV NS3 protease gene in 247 patients (135 HCV-monoinfected and 112 HIV-HCV-coinfected patients). HCV RNA was extracted from plasma and a fragment of 765 base pairs from the NS3 region was amplified and sequenced with Sanger-based technology. RESULTS: HIV-HCV-coinfected patients were more likely to be older than 40 years and have an HCV subtype-1a infection. Overall, 21.9% of patients had at least one amino acid substitution in the NS3 region; 14 patients (5.7%) harboured at least one resistance mutation (T54S, V55A, Q80R) and the Q80K mutation was not found in our case series. There was no difference between monoinfected and coinfected patients regarding the frequency of natural polymorphisms and resistance mutations. CONCLUSIONS: Baseline HCV NS3 amino acid substitutions identified herein are considered mostly natural polymorphisms with no clinical impact on PI-based therapy. The identified resistance mutations may be associated with low-level resistance to PIs in vitro. Q80K substitution seems to be a rare event in Brazil. HIV coinfection was not associated with a greater frequency of such substitutions in the studied sample.

Epidemiology of HCC in Brazil: incidence and risk factors in a ten-year cohort.

BACKGROUND AND AIM: The lack of information about hepatocellular carcinoma (HCC) in Brazil weakens health policy in preventing deaths from the illness. The aim of this study was to establish the cumulative incidence and the risk factors for hepatocellular carcinoma development in patients under a surveillance program. MATERIAL AND METHODS: 884 patients with compensated cirrhosis were prospectively followed up for at least five years, from August 1998 until August 2008, with at least one annual ultrasonography liver examination and serum alpha fetoprotein (AFP) measurement. RESULTS: Among 884 patients, 72 (8.1%) developed a tumor with a median follow up of 21.4 months. In the hepatocellular carcinoma group, hepatitis C virus infection was the major etiological factor (65.3%), 56.9% (41/72) were male and the mean average age was 57 ± 10 years. The annual incidence of hepatocellular carcinoma was 2.9%. 79.2% (57/72) of HCCs were detected within Milan Criteria, and the mean survival time was 52.3 months, significantly higher than for those outside Milan, with a mean time of 40.6 months (p = 0.0003). CONCLUSION: The annual incidence of HCC among this large series of Brazilian cirrhotic patients was around 2.9% with a detection rate of 8.1%, or a cumulative incidence rate over five years of 14.3%. The three variables related to HCC risk were low serum albumin [HR: 0.518 (0.46-0.78)], high AFP > 20 ng/mL [HR: 3.16 (1.86-5.38)], and ethnicity (Brazilian-East Asian descendants vs. other mixed Brazilian ethnicities) [HR: 2.86 (1.48-5.53)].

Distribution of hepatitis B virus subgenotype F2a in São Paulo, Brazil.

BACKGROUND: HBV genotype F is primarily found in indigenous populations from South America and is classified in four subgenotypes (F1 to F4). Subgenotype F2a is the most common in Brazil among genotype F cases. The aim of this study was to characterize HBV genotype F2a circulating in 16 patients from São Paulo, Brazil. Samples were collected between 2006 and 2012 and sent to Hospital Israelita Albert Einstein. A fragment of 1306 bp partially comprising HBsAg and DNA polymerase coding regions was amplified and sequenced. Viral sequences were genotyped by phylogenetic analysis using reference sequences from GenBank (n=198), including 80 classified as subgenotype F2a. Bayesian Markov chain Monte Carlo simulation implemented in BEAST v.1.5.4 was applied to obtain the best possible estimates using the model of nucleotide substitutions GTR+G+I. FINDINGS: It were identified three groups of sequences of subgenotype F2a: 1) 10 sequences from São Paulo state; 2) 3 sequences from Rio de Janeiro and one from São Paulo states; 3) 8 sequences from the West Amazon Basin. CONCLUSIONS: These results showing for the first time the distribution of F2a subgenotype in Brazil. The spreading and the dynamic of subgenotype F2a in Brazil requires the study of a higher number of samples from different regions as it is unfold in almost all Brazilian populations studied so far. We cannot infer with certainty the origin of these different groups due to the lack of available sequences. Nevertheless, our data suggest that the common origin of these groups probably occurred a long time ago.

Epidemiological update of hepatitis B, C and delta in Latin America.

Viral hepatitis B, C and delta still remain a serious problem in Latin America. Data from the 1980s indicated that HBV and HDV infection are the main causes of chronic hepatitis. However, the spread of HBV infection could be controlled through the implementation of immunization programmes. Different countries from Mexico to Argentina display marked differences in terms of HBV genotype distribution. HBV genotype F has been identified as the most frequent in most Latin America countries, except for Mexico and Brazil, where genotypes H and A are the most frequent, respectively. In Latin America, the overall prevalence of HCV antibody is estimated to be 1.5%. Latin American countries have been very proactive in screening their blood supplies, thus minimizing risk of HCV transmission through transfusion. The number of diagnosed and treated patients is still low, thereby increasing the burden of complications such as liver cirrhosis or hepatocellular carcinoma. The most prevalent HCV genotype is 1, which is the genotype with the greatest worldwide spread, but it is a different genotype from other regions like Africa and Asia. HDV is present worldwide but its distribution pattern is not uniform. HDV was recently detected in novel geographic regions, reinforcing that it is a very serious health threat in under-developed countries. The main prevalence areas are the Mediterranean basin, the Middle East, central and northern Asia, western and central Africa, the Amazonian basin (Brazil, Peru, Venezuela and Colombia) and the Pacific islands. Novel strategies to increase HBV immunization in the Latin American population are needed to warrant thorough coverage in the rural areas.

An update on HDV: virology, pathogenesis and treatment.

Hepatitis delta is an inflammatory liver disease caused by infection with HDV. HDV is a single-stranded circular RNA pathogen with a diameter of 36 nm. HDV is classified in the genus Deltavirus and is still awaiting a final taxonomic classification up to the family level. HDV shares similarities with satellite RNA and viroids including a small circular single-stranded RNA with secondary structure that replicates through the 'double rolling circle' mechanism. The HDV RNA genome is capable of self-cleavage through a ribozyme and encodes only one structural protein, the hepatitis delta antigen (HDAg), from the antigenomic RNA. There are two forms of HDAg, a shorter (S; 22 kDa) and a longer (L; 24 kDa) form, the latter generated from an RNA editing mechanism. The S form is essential for viral genomic replication. The L form participates in the assembly and formation of HDV. For complete replication and transmission, HDV requires the hepatitis B surface antigen (HBsAg). Thus, HDV infection only occurs in HBsAg-positive individuals, either as acute coinfection in treatment-naive HBV-infected persons, or as superinfection in patients with pre-existing chronic hepatitis B (CHB). HDV is found throughout the world, but its prevalence, incidence, clinical features and epidemiological characteristics vary by geographic region. There are eight genotypes (1 to 8) distributed over different geographic areas: HDV-1 is distributed worldwide, whereas HDV-2 to 8 are seen more regionally. Levels of HDV viraemia change over the course of HDV infection, being significantly higher in patients with early chronic hepatitis than in cirrhosis. Chronic HDV infection leads to more severe liver disease than chronic HBV monoinfection with an accelerated course of fibrosis progression, an increased risk of hepatocellular carcinoma and early decompensation in the setting of established cirrhosis. Current treatments include pegylated interferon-α and liver transplantation; the latter of which can be curative. Further studies are needed to develop better treatment strategies for this challenging disease.

Evolutionary rates and HBV: issues of rate estimation with Bayesian molecular methods.

BACKGROUND: HBV infection is a public health problem affecting approximately 2 billion people and leading to >350 million chronic carriers of the virus worldwide. Phylogenetic analysis can give valuable insight to help in clarifying the history of viral infections around the world and in elucidating routes of transmission of the different viral strains present in the infected host population. These analyses rely on an accurate estimate of the rate of mutations. METHODS: In this study, we investigated the robustness of rate estimations based on Bayesian analysis obtained so far and examined, in particular, the choice of prior for the substitution rate. RESULTS: Most previous studies have concentrated on estimating the parameters of simple demographic models for HBV, such as exponential growth and constant population size. Here, we introduce a method that automatically partitions the genome in components that show a different rate of mutation and fit different substitution models. CONCLUSIONS: In conclusion, we find that, due to inaccuracy in the sampling dates from the samples where viral sequences were obtained, lack of a sufficiently large geographical and time spread of available and trustworthy sample dates, sensitivity to priors and model misspecification and rate estimation based on molecular methods, are not reliable. We suggest that rate estimates taking into account calibration points based on relevant historical events are more robust due to the lack of trustworthy sampling dates. For example, the known history of colonization of the Americas should be used to accurately study the current diversity of genotype F, which is the most frequent genotype in almost all Spanish speaking countries in South America.

Distribution of HBV genotypes in Latin America.

Approximately 2 billion people worldwide are infected with HBV, and 350 million people are chronic carriers. HBV is classified into nine genotypes (A to I). Genotype F is the most prevalent in the Spanish-speaking countries and in the Amerindian population in South America. HBV genotype F was primarily found in indigenous populations from South America and is divided into four subgenotypes (F1 to F4). Subgenotype F1 is further divided into F1a (found in Costa Rica and El Salvador) and F1b (found in in Alaska, Argentina and Chile). Subgenotypes F2 and F3 cocirculate in the north of South America: F2a is found in Brazil and Venezuela, F2b is described only in Venezuela, F3 is frequent in Colombia, Venezuela and Panama, and F4 is reported from the central and south areas of South America, including Bolivia, Argentina and southern Brazil. HBV genotypes and subgenotypes have distinct geographical distributions. It is currently under discussion whether they are associated with different prognoses, considering the patterns of severity of liver diseases in various populations. Furthermore, global human migrations affect the pattern of genotype distribution, introducing genotypes differing from those found in the original inhabitants.

Origin of HBV and its arrival in the Americas--the importance of natural selection on time estimates.

BACKGROUND: The strong geographic structure shown by the global pattern of HBV lineages suggests an ancient origin for this virus; however, estimates based on the molecular clock suggest a very recent origin for the Native American genotypes F and H. In this study, we contribute to this debate by estimating the divergence times of genotypes F and H and by discussing how evolutionary rates estimated from recent samples may underestimate the divergence time of more ancient nodes in HBV phylogenies. METHODS: A total of 108 complete HBV genotype F and H genomes were compared to 44 reference genomes from other genotypes. Time estimates were based on a Bayesian method with evolutionary rates taken from the literature. To assess the pattern of substitutions in recent versus old branches we mapped the phylogenetic distribution of all mutations occurring in genotypes F and H using a maximum likelihood approach and compared the number of synonymous and non-synonymous mutations in young and old branches of HBV genotype F and H phylogeny using a χ² test. RESULTS: Estimated divergence times between genotypes F and H depend heavily on the evolutionary rate. While fast rates suggest a recent separation of these genotypes (approximately 800 years ago), slow rates suggest an earlier divergence (up to approximately 13,000 years ago). There is a clear excess of non-synonymous substitutions in the most recent branches of HBV phylogeny (P=4.87×10⁻¹5), most likely suggesting the action of purifying selection. CONCLUSIONS: These results suggest that rates estimated based on recent samples will overestimate the evolutionary rate and underestimate the coalescence times for ancient nodes in HBV phylogeny.

Phylogenetic analysis of complete genome sequences of hepatitis B virus from an Afro-Colombian community: presence of HBV F3/A1 recombinant strain.

BACKGROUND: Hepatitis B virus (HBV) infection is one of the most prevalent viral infections in humans and represents a serious public health problem. In Colombia, our group reported recently the presence of subgenotypes F3, A2 and genotype G in Bogotá. The aim of this study was to characterize the HBV genotypes circulating in Quibdó, the largest Afro-descendant community in Colombia. Sixty HBsAg-positive samples were studied. A fragment of 1306 bp (S/POL) was amplified by nested PCR. Positive samples to S/POL fragment were submitted to PCR amplification of the HBV complete genome. FINDINGS: The distribution of HBV genotypes was: A1 (52.17%), E (39.13%), D3 (4.3%) and F3/A1 (4.3%). An HBV recombinant strain subgenotype F3/A1 was found for the first time. CONCLUSIONS: This study is the first analysis of complete HBV genome sequences from Afro-Colombian population. It was found an important presence of HBV/A1 and HBV/E genotypes. A new recombinant strain of HBV genotype F3/A1 was reported in this population. This fact may be correlated with the introduction of these genotypes in the times of slavery.

Distribution and molecular characterization of hepatitis C virus (HCV) genotypes in patients with chronic infection from Pernambuco State, Brazil.

Hepatitis C virus (HCV) is a public health problem throughout the world and 3% of the world population is infected with this virus. It is estimated that 3-4 millions individuals are being infected every year. It has been estimated that around 1.5% of Brazilian population is anti-HCV positive and the Northeast region showed the highest prevalence in Brazil. The aim of this study was to characterize HCV genotypes circulating in Pernambuco State (PE), Brazil, located in the Northeast region of the country. This study included 85 anti-HCV positive patients followed up between 2004 and 2011. For genotyping, a 380bp fragment of HCV RNA in the NS5B region was amplified by nested PCR. Phylogenetic analysis was conducted using Bayesian Markov chain Monte Carlo simulation (MCMC) using BEAST v.1.5.3. From 85 samples, 63 (74.1%) positive to NS5B fragment were successfully sequenced. Subtype 1b was the most prevalent in this population (42-66.7%), followed by 3a (16-25.4%), 1a (4-6.3%) and 2b (1-1.6%). Twelve (63.1%) and seven (36.9%) patients with HCV and schistosomiasis were infected with subtypes 1b and 3a, respectively. Brazil is a large country with many different population backgrounds; a large variation in the frequencies of HCV genotypes is predictable throughout its territory. This study reports HCV genotypes from Pernambuco State where subtype 1b was found to be the most prevalent. Phylogenetic analysis suggests the presence of the different HCV strains circulating within this population.

Analysis of hepatitis C virus intrahost diversity across the coding region by ultradeep pyrosequencing.

Hepatitis C virus (HCV) is the leading cause of liver disease worldwide. In this study, we analyzed four treatment-naïve patients infected with subtype 1a and performed Roche/454 pyrosequencing across the coding region. We report the presence of low-level drug resistance mutations that would most likely have been missed using conventional sequencing methods. The approach described here is broadly applicable to studies of viral diversity and could help to improve the efficacy of direct-acting antiviral agents (DAA) in the treatment of HCV-infected patients.

Hepatitis delta in HIV/HBV co-infected patients in Brazil: is it important?

OBJECTIVES: This study was carried out to evaluate the prevalence of hepatitis delta virus (HDV) among human immunodeficiency virus (HIV)/hepatitis B virus (HBV) co-infected patients from São Paulo, in the Southeast Region of Brazil. METHODS: A total of 3259 HIV patients with serological markers for HBV were initially enrolled in the study. Among these patients, 154 (4.7%) were hepatitis B surface antigen (HBsAg)-reactive. Serum samples were obtained from 86 HBsAg-positive patients and were submitted to anti-HDV serological assay. RESULTS: One (1.2%) HIV/HBV patient was found to be anti-HDV-positive, and the HDV infection was confirmed by PCR. Phylogenetic analysis showed that this HDV sequence grouped with other HDV genotype 1 sequences from Mediterranean European countries, suggesting that this virus has a common ancestor with HDV from that region. This patient was probably infected by sexual transmission, as he reported unprotected sexual intercourse with multiple partners over the course of many years but denied intravenous drug use or any travel to the Brazilian Amazon, an area known to have a high HDV prevalence. CONCLUSIONS: HDV infection is infrequent in the Southeast Region of Brazil, however there have been a few cases in this region. HIV/HBV patients are at potential risk for HDV infection, therefore investigations for the presence of HDV infection must be carried out in these patients.

Detection of Hepatitis B virus subgenotype A1 in a Quilombo community from Maranhão, Brazil.

BACKGROUND: The Brazilian population is mainly descendant from European colonizers, Africans and Native Americans. Some Afro-descendants lived in small isolated communities since the slavery period. The epidemiological status of HBV infection in Quilombos communities from northeast of Brazil remains unknown. The aim of this study was to characterize the HBV genotypes circulating inside a Quilombo isolated community from Maranhão State, Brazil. METHODS: Seventy-two samples from Frechal Quilombo community at Maranhão were collected. All serum samples were screened by enzyme-linked immunosorbent assays for the presence of hepatitis B surface antigen (HBsAg). HBsAg positive samples were submitted to DNA extraction and a fragment of 1306 bp partially comprising HBsAg and polymerase coding regions (S/POL) was amplified by nested PCR and its nucleotide sequence was determined. Viral isolates were genotyped by phylogenetic analysis using reference sequences from each genotype obtained from GenBank (n = 320). Sequences were aligned using Muscle software and edited in the SE-AL software. Bayesian phylogenetic analyses were conducted using Markov Chain Monte Carlo (MCMC) method to obtain the MCC tree using BEAST v.1.5.3. RESULTS: Of the 72 individuals, 9 (12.5%) were HBsAg-positive and 4 of them were successfully sequenced for the 1306 bp fragment. All these samples were genotype A1 and grouped together with other sequences reported from Brazil. CONCLUSIONS: The present study represents the first report on the HBV genotypes characterization of this community in the Maranhão state in Brazil where a high HBsAg frequency was found. In this study, we reported a high frequency of HBV infection and the exclusive presence of subgenotype A1 in an Afro-descendent community in the Maranhão State, Brazil.

Phylogenetic analysis of hepatitis B virus genotype F complete genome sequences from Chilean patients with chronic infection.

Molecular epidemiological data concerning the hepatitis B virus (HBV) in Chile are not known completely. Since the HBV genotype F is the most prevalent in the country, the goal of this study was to obtain full HBV genome sequences from patients infected chronically in order to determine their subgenotypes and the occurrence of resistance-associated mutations. Twenty-one serum samples from antiviral drug-naive patients with chronic hepatitis B were subjected to full-length PCR amplification, and both strands of the whole genomes were fully sequenced. Phylogenetic analyses were performed along with reference sequences available from GenBank (n = 290). The sequences were aligned using Clustal X and edited in the SE-AL software. Bayesian phylogenetic analyses were conducted by Markov Chain Monte Carlo simulations (MCMC) for 10 million generations in order to obtain the substitution tree using BEAST. The sequences were also analyzed for the presence of primary drug resistance mutations using CodonCode Aligner Software. The phylogenetic analyses indicated that all sequences were found to be the HBV subgenotype F1b, clustered into four different groups, suggesting that diverse lineages of this subgenotype may be circulating within this population of Chilean patients.

Frequency and genotypic distribution of GB virus C (GBV-C) among Colombian population with Hepatitis B (HBV) or Hepatitis C (HCV) infection.

BACKGROUND: GB virus C (GBV-C) is an enveloped positive-sense ssRNA virus belonging to the Flaviviridae family. Studies on the genetic variability of the GBV-C reveals the existence of six genotypes: genotype 1 predominates in West Africa, genotype 2 in Europe and America, genotype 3 in Asia, genotype 4 in Southwest Asia, genotype 5 in South Africa and genotype 6 in Indonesia. The aim of this study was to determine the frequency and genotypic distribution of GBV-C in the Colombian population. METHODS: Two groups were analyzed: i) 408 Colombian blood donors infected with HCV (n = 250) and HBV (n = 158) from Bogotá and ii) 99 indigenous people with HBV infection from Leticia, Amazonas. A fragment of 344 bp from the 5' untranslated region (5' UTR) was amplified by nested RT PCR. Viral sequences were genotyped by phylogenetic analysis using reference sequences from each genotype obtained from GenBank (n = 160). Bayesian phylogenetic analyses were conducted using Markov chain Monte Carlo (MCMC) approach to obtain the MCC tree using BEAST v.1.5.3. RESULTS: Among blood donors, from 158 HBsAg positive samples, eight 5.06% (n = 8) were positive for GBV-C and from 250 anti-HCV positive samples, 3.2%(n = 8) were positive for GBV-C. Also, 7.7% (n = 7) GBV-C positive samples were found among indigenous people from Leticia. A phylogenetic analysis revealed the presence of the following GBV-C genotypes among blood donors: 2a (41.6%), 1 (33.3%), 3 (16.6%) and 2b (8.3%). All genotype 1 sequences were found in co-infection with HBV and 4/5 sequences genotype 2a were found in co-infection with HCV. All sequences from indigenous people from Leticia were classified as genotype 3. The presence of GBV-C infection was not correlated with the sex (p = 0.43), age (p = 0.38) or origin (p = 0.17). CONCLUSIONS: It was found a high frequency of GBV-C genotype 1 and 2 in blood donors. The presence of genotype 3 in indigenous population was previously reported from Santa Marta region in Colombia and in native people from Venezuela and Bolivia. This fact may be correlated to the ancient movements of Asian people to South America a long time ago.

Distribution of hepatitis c virus (hcv) genotypes in patients with chronic infection from Rondônia, Brazil.

BACKGROUND: Hepatitis C virus (HCV) is an important human pathogen affecting around 3% of the human population. In Brazil, it is estimated that there are approximately 2 to 3 million HCV chronic carriers. There are few reports of HCV prevalence in Rondônia State (RO), but it was estimated in 9.7% from 1999 to 2005. The aim of this study was to characterize HCV genotypes in 58 chronic HCV infected patients from Porto Velho, Rondônia (RO), Brazil. METHODS: A fragment of 380 bp of NS5B region was amplified by nested PCR for genotyping analysis. Viral sequences were characterized by phylogenetic analysis using reference sequences obtained from the GenBank (n = 173). Sequences were aligned using Muscle software and edited in the SE-AL software. Phylogenetic analyses were conducted using Bayesian Markov chain Monte Carlo simulation (MCMC) to obtain the MCC tree using BEAST v.1.5.3. RESULTS: From 58 anti-HCV positive samples, 22 were positive to the NS5B fragment and successfully sequenced. Genotype 1b was the most prevalent in this population (50%), followed by 1a (27.2%), 2b (13.6%) and 3a (9.0%). CONCLUSIONS: This study is the first report of HCV genotypes from Rondônia State and subtype 1b was found to be the most prevalent. This subtype is mostly found among people who have a previous history of blood transfusion but more detailed studies with a larger number of patients are necessary to understand the HCV dynamics in the population of Rondônia State, Brazil.

Characterization of hepatitis B virus (HBV) genotypes in patients from Rondônia, Brazil.

BACKGROUND: Hepatitis B virus (HBV) can be classified into nine genotypes (A-I) defined by sequence divergence of more than 8% based on the complete genome. This study aims to identify the genotypic distribution of HBV in 40 HBsAg-positive patients from Rondônia, Brazil. A fragment of 1306 bp partially comprising surface and polymerase overlapping genes was amplified by PCR. Amplified DNA was purified and sequenced. Amplified DNA was purified and sequenced on an ABI PRISM® 377 Automatic Sequencer (Applied Biosystems, Foster City, CA, USA). The obtained sequences were aligned with reference sequences obtained from the GenBank using Clustal X software and then edited with Se-Al software. Phylogenetic analyses were conducted by the Markov Chain Monte Carlo (MCMC) approach using BEAST v.1.5.3. RESULTS: The subgenotypes distribution was A1 (37.1%), D3 (22.8%), F2a (20.0%), D4 (17.1%) and D2 (2.8%). CONCLUSIONS: These results for the first HBV genotypic characterization in Rondônia state are consistent with other studies in Brazil, showing the presence of several HBV genotypes that reflects the mixed origin of the population, involving descendants from Native Americans, Europeans, and Africans.