Antigenic diversity of hepatitis B virus strains of genotype F in Amerindians and other population groups from Venezuela

Hepatitis B virus American genotypes: Pathogenic variants ?

Hepatitis B virus (HBV) chronic infection is responsible for almost 900.000 deaths each year, due to cirrhosis or hepatocellular carcinoma (HCC). Ten HBV genotypes have been described (A-J). HBV genotype F and H circulate in America. HBV genotypes have been further classified in subgenotypes. There is a strong correlation between the genetic admixture of the American continent and the frequency of genotypes F or H: a high frequency of these genotypes is found in countries with a population with a higher ratio of Amerindian to African genetic admixture. The frequency of occult HBV infection in Amerindian communities from Latin America seems to be higher than the one found in other HBV-infected groups, but its association with American genotypes is unknown. There is growing evidence that some genotypes might be associated with a faster evolution to HCC. In particular, HBV genotype F has been implicated in a frequent and rapid progression to HCC. However, HBV genotype H has been associated to a less severe progression of disease. This study reviews the diversity and frequency of autochthonous HBV variants in the Americas and evaluates their association to severe progression of disease. Although no significant differences were found in the methylation pattern between different genotypes and subgenotypes of the American types, basal core promoter mutations might be more frequent in some subgenotypes, such as F1b and F2, than in other American subgenotypes or genotype H. F1b and probably F2 may be associated with a severe presentation of liver disease as opposed to a more benign course for subgenotype F4 and genotype H. Thus, preliminary evidence suggests that not all of the American variants are associated with a rapid progression to HCC.

A novel hepatitis B virus species discovered in capuchin monkeys sheds new light on the evolution of primate hepadnaviruses

BACKGROUND & AIMS

All known hepatitis B virus (HBV) genotypes occur in humans and hominoid Old World non-human primates (NHPs). The divergent woolly monkey HBV (WMHBV) forms another orthohepadnavirus species. The evolutionary origins of HBV are unclear.

METHODS

We analysed sera from 124 Brazilian monkeys collected during 2012-2016 for hepadnaviruses using molecular and serological tools, and conducted evolutionary analyses.

RESULTS

We identified a novel orthohepadnavirus species in capuchin monkeys (capuchin monkey hepatitis B virus [CMHBV]). We found CMHBV-specific antibodies in five animals and high CMHBV concentrations in one animal. Non-inflammatory, probably chronic infection was consistent with an intact preCore domain, low genetic variability, core deletions in deep sequencing, and no elevated liver enzymes. Cross-reactivity of antisera against surface antigens suggested antigenic relatedness of HBV, CMHBV, and WMHBV. Infection-determining CMHBV surface peptides bound to the human HBV receptor (human sodium taurocholate co-transporting polypeptide), but preferentially interacted with the capuchin monkey receptor homologue. CMHBV and WMHBV pseudotypes infected human hepatoma cells via the human sodium taurocholate co-transporting polypeptide, and were poorly neutralised by HBV vaccine-derived antibodies, suggesting that cross-species infections may be possible. Ancestral state reconstructions and sequence distance comparisons associated HBV with humans, whereas primate hepadnaviruses as a whole were projected to NHP ancestors. Co-phylogenetic analyses yielded evidence for co-speciation of hepadnaviruses and New World NHP. Bayesian hypothesis testing yielded strong support for an association of the HBV stem lineage with hominoid ancestors. Neither CMHBV nor WMHBV was likely the ancestor of the divergent human HBV genotypes F/H found in American natives.

CONCLUSIONS

Our data suggest ancestral co-speciation of hepadnaviruses and NHP, and an Old World origin of the divergent HBV genotypes F/H. The identification of a novel primate hepadnavirus offers new perspectives for urgently needed animal models of chronic hepatitis B.

LAY SUMMARY

The origins of HBV are unclear. The new orthohepadnavirus species from Brazilian capuchin monkeys resembled HBV in elicited infection patterns and could infect human liver cells using the same receptor as HBV. Evolutionary analyses suggested that primate HBV-related viruses might have emerged in African ancestors of New World monkeys millions of years ago. HBV was associated with hominoid primates, including humans and apes, suggesting evolutionary origins of HBV before the formation of modern humans. HBV genotypes found in American natives were divergent from those found in American monkeys, and likely introduced along prehistoric human migration. Our results elucidate the evolutionary origins and dispersal of primate HBV, identify a new orthohepadnavirus reservoir, and enable new perspectives for animal models of hepatitis B.

Genotype characteristic and phylogenetic analysis of hepatitis B virus in northeast-Iran

Viral hepatitis is considered as a worldwide health problem and hepatitis B virus (HBV) infection is one of the major health concerns which are annually responsible for more than one million deaths. HBV can be classified into at least eight genotypes, A-H and four major subtypes. Predominant HBV genotype in Mediterranean and Middle East countries is genotype D, but there is a few studies have been performed on the HBV genotype in Iran. The genotype characteristic and phylogenetic analyses were determined in chronic HBV patients in the northeast of Iran. First, seventy-eight patients with chronic HBV infection were enrolled. Demographic features were reviewed and sera samples were collected. HBV genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method, and results were confirmed by sequencing. Finally, a phylogenetic tree was obtained using Geneious software. Sixty-two (79.48%) of patients were males (mean age: 36.82 years). Twelve out of 78 patients (15.4%) were hepatitis B envelope antigen (HBeAg)-reactive. There were no significant differences between the clinical and HBeAg-positive serological data and HBeAb positive individuals. RFLP DNA sequencing and phylogenetic analysis showed that genotype D was the only genotype which observed in Mashhad, northeast of Iran. This is the first report of HBV genotyping in Mashhad. The results revealed that genotype D was the only genotype detected in this area which was consistence with previous studies in the Middle East, Mediterranean countries, southwest and center of Iran.

Different patterns of codon usage in the overlapping polymerase and surface genes of hepatitis B virus suggest a de novo origin by modular evolution

The polymerase (P) and surface (S) genes of hepatitis B virus (HBV) show the longest gene overlap in animal viruses. Gene overlaps originate by the overprinting of a novel frame onto an ancestral pre-existing frame. Identifying which frame is ancestral and which frame is de novo (the genealogy of the overlap) is an appealing topic. However, the P/S overlap of HBV is an intriguing paradox, because both genes are indispensable for virus survival. Thus, the hypothesis of a primordial virus without the surface protein or without the polymerase makes no biological sense. With the aim to determine the genealogy of the overlap, the codon usage of the overlapping frames P and S was compared to that of the non-overlapping region. It was found that the overlap of human HBV had two patterns of codon usage. One was localized in the 5′ one-third of the overlap and the other in the 3′ two-thirds. By extending the analysis to non-human HBVs, it was found that this feature occurred in all hepadnaviruses. Under the assumption that the ancestral frame has a codon usage significantly closer to that of the non-overlapping region than the de novo frame, the ancestral frames in the 5′ and 3′ region of the overlap could be predicted. They were, respectively, frame S and frame P. These results suggest that the spacer domain of the polymerase and the S domain of the surface protein originated de novo by overprinting. They support a modular evolution hypothesis for the origin of the overlap.

HBV genotypic variability in Cuba

The genetic diversity of HBV in human population is often a reflection of its genetic admixture. The aim of this study was to explore the genotypic diversity of HBV in Cuba. The S genomic region of Cuban HBV isolates was sequenced and for selected isolates the complete genome or precore-core sequence was analyzed. The most frequent genotype was A (167/250, 67%), mainly A2 (149, 60%) but also A1 and one A4. A total of 77 isolates were classified as genotype D (31%), with co-circulation of several subgenotypes (56 D4, 2 D1, 5 D2, 7 D3/6 and 7 D7). Three isolates belonged to genotype E, two to H and one to B3. Complete genome sequence analysis of selected isolates confirmed the phylogenetic analysis performed with the S region. Mutations or polymorphisms in precore region were more common among genotype D compared to genotype A isolates. The HBV genotypic distribution in this Caribbean island correlates with the Y lineage genetic background of the population, where a European and African origin prevails. HBV genotypes E, B3 and H isolates might represent more recent introductions.

Molecular epidemiology and genotyping of hepatitis B virus of HBsAg-positive patients in Oman

Background

Hepatitis B virus (HBV) infection is a major global health burden with distinct geographic public health significance. Oman is a country with intermediate HBV carrier prevalence; however, little is known about the incidence of HBV variants in circulation. We investigated the HBV genotype distribution, the occurrence of antiviral resistance, and HBV surface antigen (HBsAg) escape mutations in HBsAg-positive patients in Oman.

Methods

Serum samples were collected from 179 chronically HBV-infected patients enrolled in various gastroenterology clinics in Oman. HBV genotypes were determined by sequencing and phylogenetic analysis. Mutations in the HBV polymerase and the HBsAg gene were characterized by mutational analysis.

Results

HBV genotypes D (130/170; 76.47%) and A (32/170; 18.28%) are predominant in Oman. The HBV genotypes C and E were less frequent (each 1.18%), while the HBV genotypes B, G, F, and H were not detected. Four patients revealed HBV genotype mixtures (HBV-A/D and D/C). The analyses of vaccine escape mutations yield that 148/170 (87.06%) HBV sequences were wild type. 22/170 (12.94%) HBV sequences showed mutations in the “a” determinant of the HBsAg domain. Two patients showed the described HBV vaccine escape mutation sP120T. 8/146 (5.48%) HBV isolates harbored mutations in the HBV polymerase known to confer resistance against antiviral therapy. Especially the lamivudine resistance mutations rtL180M/rtM204V and rtM204I were detected.

Conclusion

This study shows the distribution of HBV genotypes, therapy resistance, and vaccine escape mutations in HBV-infected patients in Oman. Our findings will have a major impact on therapy management and diagnostics of chronic HBV infections in Oman to control HBV infection in this intermediate HBV-endemic country.

Molecular epidemiology of hepatitis B and hepatitis delta viruses circulating in the Western Amazon region, North Brazil

Background

Hepatitis B virus (HBV) and hepatitis D virus (HDV) represent important public health problems in the Western Amazon region with reported cases of fulminant hepatitis. This cross sectional study describes HBV and HDV genotypes circulating in the Brazilian Amazon region.

Methods

HBsAg positive individuals (n = 224) were recruited in Manaus/Amazonas State (130 blood donors from the Hematology and Hemotherapy Foundation from Amazonas/HEMOAM; 60 subjects from outpatient clinic) and in Eirunepe city (n = 34) from 2003–2009. Most participants (n = 153) lived in Manaus, 63 were from 20 remote isolated municipalities, 8 lived outside Amazonas State. Genotyping was based on PCR products: HBV genotype A-F specific primers, restricted length polymorphism for HDV. HDV isolates were directly sequenced (delta antigen 405 nucleotide fragment) and phylogenetic analysis performed (MEGA; neighbor-joining, Kimura’s two parameter).

Results

Most participants were young adult males and HBV mono-infection predominated (70.5%, 158/224). Among blood donors, outpatient subjects and individuals from Eirunepe, HBV/A prevailed followed by HBV/D and F (p > 0.05). HBV/A was more frequent in blood donors (p < 0.05). HBV-HDV coinfection rate was 8.5% in blood donors (11/130), 65.0% (39/60) in outpatient subjects and 47.0% (16/34) in individuals from Eirunepe. Compared to blood donors, coinfection was higher in outpatient subjects (65.0% versus 8.5%; RR = 5.0; CI 3.4-7.9; p < 0.0001) and in subjects from Eirunepe (47.0% versus 8.5%; RR = 5.5; CI 3.0-9.9; p < 0.0001). HBV-HDV coinfection rates were higher in patients from highly endemic remote cities. Only HDV genotype 3 was detected, HBV/F-HDV/3 predominated (20/38; 52.7%), followed by HBV/A-HDV/3 (31.6%; 12/38) and HBV/D-HDV/3 (15.8%; 6/38).

Conclusions

The description of HBV and HDV genotypes circulating in the western Amazon can contribute to a better understanding of their relevance on the regional epidemics. These infections are highly endemic in the Amazon where their control is challenged by its vast territorial dimension with small, hard-to-reach municipalities dispersed into the jungle and populated by diverse ethnic groups.

Molecular characterisation of hepatitis B virus in the resident Chinese population in Panama City

Despite the effectiveness of current hepatitis B virus (HBV) vaccines, it is estimated that 350 million individuals suffer from chronic HBV infection and more than 50% of these affected individuals live on the Asian continent. Panama is a country with a great diversity of foreign groups; the Chinese community is a large example of this phenomenon. There is an urgent need to perform studies that evaluate the prevalence and the genetic diversity of HBV in this community. This study aimed to evaluate the prevalence of HBV and its genotypes and mutant variants in the Chinese population residing in Panama. In total, 320 subjects were enrolled in the study. Forty-two subjects (13.1%) were positive for HBsAg and HBV-DNA from 18 subjects revealed the presence of genotypes B2 and C1. Secondary mutations associated with drug resistance at positions rtV207L and rtN239T of the reverse transcriptase gene were identified. Additionally, the mutation pair A1762T/G1764A was found in three samples and the mutation G1896A was detected in an HBeAg-negative subject. In conclusion, to our knowledge, this is the first study to report high HBV prevalence rates in resident ethnic Chinese in Central America and the presence of genotypes B2 and C1 in this region.

Molecular characterisation of hepatitis B virus in the resident Chinese population in Panama City

Despite the effectiveness of current hepatitis B virus (HBV) vaccines, it is estimated that 350 million individuals suffer from chronic HBV infection and more than 50% of these affected individuals live on the Asian continent. Panama is a country with a great diversity of foreign groups; the Chinese community is a large example of this phenomenon. There is an urgent need to perform studies that evaluate the prevalence and the genetic diversity of HBV in this community. This study aimed to evaluate the prevalence of HBV and its genotypes and mutant variants in the Chinese population residing in Panama. In total, 320 subjects were enrolled in the study. Forty-two subjects (13.1%) were positive for HBsAg and HBV-DNA from 18 subjects revealed the presence of genotypes B2 and C1. Secondary mutations associated with drug resistance at positions rtV207L and rtN239T of the reverse transcriptase gene were identified. Additionally, the mutation pair A1762T/G1764A was found in three samples and the mutation G1896A was detected in an HBeAg-negative subject. In conclusion, to our knowledge, this is the first study to report high HBV prevalence rates in resident ethnic Chinese in Central America and the presence of genotypes B2 and C1 in this region.

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.

Phylogeography and evolutionary history of hepatitis B virus genotype F in Brazil

Background

Hepatitis B virus (HBV) genotype F (HBV/F) is considered to be indigenous to the Americas, but its emergence and spread in the continent remain unknown. Previously, only two HBV/F complete genome sequences from Brazil were available, limiting the contribution of Brazilian isolates to the phylogenetic studies of HBV/F. The present study was carried out to assess the proportion and geographic distributions of HBV/F subgenotypes in Brazil, to determine the full-length genomic sequences of HBV/F isolates from different Brazilian geographic regions, and to investigate the detailed evolutionary history and phylogeography of HBV/F in Brazil.

Methods

Complete HBV/F genomes isolated from 12 Brazilian patients, representing the HBV/F subgenotypes circulating in Brazil, were sequenced and analyzed together with sequences retrieved from GenBank, using the Bayesian coalescent and phylogeographic framework.

Results

Phylogenetic analysis using all Brazilian HBV/F S-gene sequences available in GenBank showed that HBV/F2a is found at higher frequencies countrywide and corresponds to all sequences isolated in the Brazilian Amazon Basin. In addition, the evolutionary analysis using complete genome sequences estimated an older median ancestral age for the Brazilian HBV/F2a compared to the Brazilian HBV/F1b and HBV/F4 subgenotypes, suggesting that HBV/F2a represents the original native HBV of Brazil. The phylogeographic patterns suggested a north-to-south flow of HBV/F2a from Venezuela to Brazil, whereas HBV/F1b and HBV/F4 strains appeared to have spread from Argentina to Brazil.

Conclusions

This study suggests a plausible route of introduction of HBV/F subgenotypes in Brazil and demonstrates the usefulness of recently developed computational tools for investigating the evolutionary history of HBV.

Molecular characterization of the hepatitis B virus in autochthonous and endogenous populations in the Western Brazilian Amazon

INTRODUCTION

Hepatitis B virus (HBV) infection is a serious public health issue worldwide. Hepatitis B virus is classified into eight genotypes, varying from A to H, with distinct geographical distributions. In Brazil, the most frequent genotypes are A, D, and F.

METHODS

This study aimed to characterize the HBV genotypes in cases of hepatitis B virus and hepatitis D virus (HDV) co-infections in an endemic area in the Western Brazilian Amazon. We analyzed 86 serum samples reactive for HBsAg from indigenous and non-indigenous populations obtained from previous serological surveys.

RESULTS

Of the 86 reactive serum samples, 39 were found to be HBV-DNA-positive by semi-nested PCR. The genotypes were established by sequencing the amplified S gene region. We obtained 20 sequences classified into three genotypes: A, D, and F. Genotype A was the most frequent (60%), followed by D (35%) and F (5%).

CONCLUSIONS

The distribution of the HBV genotypes reflected the pattern of historical occupation of the region.

Dynamics of hepatitis D (delta) virus genotype 3 in the Amazon region of South America

Hepatitis delta virus (HDV) is widely distributed and associated with fulminant hepatitis epidemics in areas with high prevalence of HBV. Several studies performed in the 1980s showed data on HDV infection in South America, but there are no studies on the viral dynamics of this virus. The aim of this study was to conduct an evolutionary analysis of hepatitis delta genotype 3 (HDV/3) prevalent in South America: estimate its nucleotide substitution rate, determine the time of most recent ancestor (TMRCA) and characterize the epidemic history and evolutionary dynamics. Furthermore, we characterized the presence of HBV/HDV infection in seven samples collected from patients who died due to fulminant hepatitis from Amazon region in Colombia and included them in the evolutionary analysis. This is the first study reporting HBV and HDV sequences from the Amazon region of Colombia. Of the seven Colombian patients, five were positive for HBV-DNA and HDV-RNA. Of them, two samples were successfully sequenced for HBV (subgenotypes F3 and F1b) and the five samples HDV positive were classified as HDV/3. By using all HDV/3 available reference sequences with sampling dates (n=36), we estimated the HDV/3 substitution rate in 1.07 × 10(-3) substitutions per site per year (s/s/y), which resulted in a time to the most recent common ancestor (TMRCA) of 85 years. Also, it was determined that HDV/3 spread exponentially from early 1950s to the 1970s in South America. This work discusses for the first time the viral dynamics for the HDV/3 circulating in South America. We suggest that the measures implemented to control HBV transmission resulted in the control of HDV/3 spreading in South America, especially after the important raise in this infection associated with a huge mortality during the 1950s up to the 1970s. The differences found among HDV/3 and the other HDV genotypes concerning its diversity raises the hypothesis of a different origin and/or a different transmission route.

New perspectives on the evolutionary history of hepatitis B virus genotype F

Hepatitis B virus (HBV) is a globally distributed human pathogen. The aim of this work was to analyze the evolutionary history of HBV genotype F, emphasizing on the study of subgenotypes prevalent in the Southern area of South America. Complete genomes of HBV genotype F from 36 samples from Argentina and Chile were sequenced and analyzed by phylogenetic and Bayesian coalescent methods along with sequences obtained from GenBank database. The phylogeography separated not only Central American from South American isolates but also revealed that different subgenotypes are distributed in constrained although not exclusive areas of the continent. The result obtained with time-stamped complete genomes failed to explain the wide geographical distribution and the clustering observed in this genotype. Conversely, the use of Bayesian coalescent analyses with substitution rates as priors, instead of the co-estimation of tMRCA and substitution rate, allowed us to propose a far origin for the HBV genotype F based on the phylogeographical and epidemiological data.

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.

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.

Diversity of hepatitis B and C viruses in Chile

Although there is a low prevalence rate (around 1% of the population) of infection with hepatitis B virus (HBV) and hepatitis C virus (HCV) in Chile, little is known about the diversity and molecular characteristics of the circulating viruses. In the present study, 40 HBV and 57 HCV samples from Santiago City, Chile, were examined. The phylogenetic analysis of HBV samples showed the autochthonous genotype F as the most represented genotype in the study (67.5%), while genotypes A, B, C, and D were less frequent (7.5%, 5%, 7.5%, and 12.5%, respectively). The frequency of circulation of HBV genotypes observed is in accordance with the genetic background of the Chilean population. Most of the HCV samples tested belonged to subtype 1b (82%). The coalescent analysis conducted for both the NS5A and NS5B regions of the HCV strains showed similar population growth rates, with a most recent common ancestor estimated to date between 1893 and 1901. This result may indicate that genotype 1b strains circulating in Chile have epidemiological features similar to those described for HCV genotype 1b in Brazil and the United States. However, the most recent common ancestor for Chile is older than that reported recently for genotype 1b in Argentina.

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.

Genetic study of hepatitis B virus in Indonesia reveals a new subgenotype of genotype B in east Nusa Tenggara

The hepatitis B virus (HBV) genotype is associated with viral anthropological history, clinical outcome of disease and response to treatment. This study examines the HBV genotypes in Indonesia. HBV genotypes were determined by whole-genome sequencing and from the sequence of the Pre-S2 and S regions in a larger series. Two HBV genotypes, B (HBV/B) and C (HBV/C), were predominant. Three previously reported HBV/B subgenotypes were identified, with certain population association: HBV/B2 (HBV/Ba) was found mostly in Indonesians of Chinese ethnic origin, HBV/B3 was dominant among the Javanese, and HBV/B5, reported earlier from the Philippines, was also discovered, albeit at low frequency. Two other subgenotypes, HBV/B4 from Vietnam and HBV/B6, recently reported from the Arctic region, were not found. A novel subgenotype, HBV/B7, was recognized, associated with populations of the Nusa Tenggara islands in eastern Indonesia. Characteristic differences in HBsAg serotype and single nucleotide polymorphisms (SNPs) in the Pre-S2 region distinguish HBV/B7 from other HBV/B subgenotypes and further establish the new HBV subgenotype.

Novel subgenotypes of hepatitis B virus genotypes C and D in Papua, Indonesia

Eight genotypes (A to H) and nine subtypes (adw2, adw4, ayw1, ayw2, ayw3, ayw4, adrq+, adrq-, and ayr) of hepatitis B virus (HBV) have been identified worldwide. They appear to be associated with geographical distribution, virological characteristics, and possibly clinical outcomes. We performed sequence analysis of part of the S gene and the entire precore/core gene of HBV isolates obtained from HBsAg-positive blood donors in Papua Province, Indonesia. Phylogenetic analysis of the S gene sequences revealed that 23 (85.2%) of the 27 HBV isolates tested belonged to genotype C (HBV/C) and 2 (7.4%) each to HBV/B and HBV/D. Interestingly, 19 (82.6%) of the 23 isolates of HBV/C clustered in a branch that was distinct from the previously reported subgenotypes C1 to C5 (HBV/C1 to HBV/C5). Similarly, two isolates of HBV/D clustered in a branch distinct from the reported subgenotypes HBV/D1 to HBV/D5. Phylogenetic analysis of the entire precore/core gene confirmed the consistent presence of the distinct branches in HBV/C and HBV/D. We therefore propose novel subgenotypes designated HBV/C6 and HBV/D6. The majority of HBV/C6 isolates in Papua had alanine at positions 159 and 177 (A159/A177) in the HBsAg. A159/A177 is different from the determinants for adrq+ (A159/V177), found throughout Asia, and adrq- (V159/A177), found in New Caledonia and Polynesia, possibly representing a unique antigenic group (provisionally referred to as adrq indeterminate). In conclusion, we have identified two novel HBV subgenotypes, HBV/C6 and HBV/D6, the first of which is the most prevalent subgenotype of HBV in Papua, Indonesia.

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.

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.

A new algorithm for deduction of hepatitis B surface antigen subtype determinants from the amino acid sequence

OBJECTIVE

We have reexamined hepatitis B virus subtypes to determine the role of specific HBsAg amino acids in serologic reactivity because of problematic genotype/subtype associations seen in a set of geographically diverse serum specimens.

METHODS

We obtained DNA sequences for 491 HBsAg-positive specimens from geographically distinct locations, determined their genotypes through phylogenetic analysis, and subtyped the specimens using an algorithm derived from published data on the molecular basis of HBsAg subtype reactivity. Problematic samples were subtyped serologically to resolve conflicts based on the amino acid sequence alone.

RESULTS

Three isolates were found to have unusual genotype/subtype associations. Examination of the isolates' amino acid sequences suggested amino acid positions 122, 127, 140, 159 and 160 can be used to determine subtype reactivity from HBsAg amino acid sequences, while position 134, previously thought to play a role, is no longer important.

CONCLUSIONS

This re-examination of hepatitis B virus subtypes shows the involvement of amino acid positions 122, 127, 140, 159 and 160 in HBsAg reactivity. While d, y, and r reactivities are controlled by single amino acid changes, w reactivity is determined by positions 122, 127, 140, and 159.

Expertise of laboratories in viral load quantification, genotyping, and precore mutant determination for hepatitis B virus in a multicenter study

A national evaluation study was performed in 14 specialized laboratories with the objective of assessing their capacities to provide (i) hepatitis B virus (HBV) viral loads (VL), (ii) HBV genotypes, and(iii) identification of precore/core mutants. The panel consisted of 12 HBV DNA-positive samples with VLs from 2.8 to 9.1 log(10) copies/ml, different HBV genotypes (A to F), and 3 mutant and 9 wild-type samples at nucleotide 1896. The coefficients of variation of the mean VLs ranged from 2.4% to 10.4% with the Cobas HBV Monitor assay, from 1.8% to 5.5% with the Cobas TaqMan 48, from 1.5 to 26.2% with RealArt HBV PCR, and from 0 to 7% with branched DNA (bDNA). The Cobas Monitor assay underestimated the VLs of genotype F samples, with differences ranging from 1.4 to 2.4 log(10) copies/ml. The accuracies of genotype determinations ranged from 33% to 100%, and those of precore mutant determinations ranged from 25 to 100%. This study showed some drawbacks of two widely used assays: (i) Cobas Monitor has a narrow dynamic range and underestimates genotype F sample VLs and (ii) bDNA shows poor sensitivity and may fail to identify patients with low VLs. With higher performance in terms of analytical sensitivity combined with a larger dynamic range and an ability to quantify the main genotypes equally, real-time PCR methods appear more appropriate for accurate monitoring of HBV DNA quantification. Furthermore, the clinical implications of HBV genotyping and the determination of precore/core mutants need to be clearly stated to justify the standardization of these methods.

Diagnostic impact of the genetic variability of the hepatitis B virus surface antigen gene

The genetic variability of hepatitis B virus (HBV) represents a challenge for the sensitivity of immunologic and molecular based assays. Genotyping studies show that the genetic diversity of HBV is very high even in industrialized countries. The analytical sensitivity of HBsAg and anti-HBs assays may be dependent on HBV genotype or subtype and could possibly lead to false negative results in samples with low-level HBsAg. It is possible that the recognition of genotypes E and F may be impaired. Immunoassays based on polyclonal capture antibody show the highest sensitivity for the recognition of recombinant mutants or serum samples harboring mutant forms of HBsAg. However, they do not guarantee full sensitivity, especially for the detection of the G145R mutation and amino acid insertions or substitutions in positions 120-123. Detection of HBsAg needs to be improved by the introduction of new HBsAg assays able to recognize so far described S gene mutants and with a lower detection threshold than current immunoassays in order to detect smallest amounts of HBsAg in low level carriers. There is also a need for more complete epidemiological data on the prevalence of HBsAg mutants especially for G145R and assays for the (differential) screening of mutants need to be developed and evaluated.

Unusual naturally occurring humoral and cellular mutated epitopes of hepatitis B virus in a chronically infected argentine patient with anti-HBs antibodies

Serum hepatitis B virus (HBV) DNA was extracted from a chronically infected patient with cocirculation of hepatitis B surface antigen (HBsAg) and anti-HBs antibodies. Direct PCR and clone-derived sequences of the S and overlapped P genes were obtained. DNA sequences and phylogenetic analysis ascribed this isolate to genotype A (serotype adw2). Five of six HBV DNA clones exhibited point mutations inside and outside the major hydrophilic region, while the sixth clone exhibited a genotype A "wild-type" amino acid sequence. Observed replacements included both humoral and/or cellular (major histocompatibility complex class I [MHC-I] and MHC-II) HBV mutated epitopes, such as S45A, P46H, L49H, C107R, T125A, M133K, I152F, P153T, T161S, G185E, A194T, G202R, and I213L. None of these mutants were individually present within a given clone. The I213L replacement was the only one observed in the five clones carrying nonsynonymous mutations in the S gene. Some of the amino acid substitutions are reportedly known to be responsible for the emergence of immune escape mutants. C107R replacement prevents disulfide bonding, thus disrupting the first loop of the HBsAg. Circulation of some of these mutants may represent a potential risk for the community, since neither current hepatitis B vaccines nor hyperimmune hepatitis B immune globulin are effectively prevent the liver disease thereto associated. Moreover, some of the recorded HBsAg variants may influence the accuracy of the results obtained with currently used diagnostic tests.

Distribution of hepatitis B virus genotypes among patients with chronic infection

Hepatitis B virus (HBV) can be classified into at least eight genotypes, A-H. We evaluated the distribution HBV genotypes among patients with chronic infection.

METHODS

We consecutively evaluated adult patients with chronic HBV infection from Salvador, Brazil. Patients were classified according to HBV infection chronic phases based on HBV-DNA levels and presence of serum HBV markers. HBV-DNA was qualitatively and quantitatively detected in serum by polymerised chain reaction (PCR). Isolates were genotyped by comparison of amino acid mutations and phylogenetic analysis.

RESULTS

One-hundred and fourteen patients were evaluated. HBV-DNA was positive in 96 samples. HBV genotype was done in 76. Mean age was 36 +/- 11.3. In 61 of 76 cases subjects were classified as inactive HBsAg carriers. Their mean HBV serum level was 1760 copies/ml and 53 of 61 were infected with HBV genotype A, seven with HBV genotype F and one with genotype B. Twelve of the 76 patients had detectable hepatitis B e-antigen (HBeAg) in serum. Ten were infected with HBV genotype A and two with genotype F; most had increased alanine aminotransferase and high HBV-DNA levels. Three patients were in the immunotolerant phase, two were infected with HBV genotype A and one with genotype F. HBV subtyping showed subtypes adw2 and adw4.

CONCLUSIONS

HBV genotype A adw2 and genotype F adw4 were the most prevalent isolates found. We could not find differences in genotype distribution according to HBV clinical phases and DNA levels. We did not detect HBV genotype D in contrast to a previous study in our center with acute hepatitis B. All inactive HBsAg carriers had low HBV-DNA levels.

HBV epidemiology in Latin America

In Latin America, despite the paucity of population studies, hepatitis B is considered endemic. The western Amazonia is a highly endemic area where hepatitis D is also prevalent. In this area, outbreaks of fulminant hepatitis due to H13V and HDV are frequently reported. Non-safe sexual activity seems to be the most important transmission route, but intrafamilial transmission, during early childhood, is extremely significant in Amazonia. The H13V genotype distribution is heterogeneous with a high prevalence of genotype F in the Amazonian region and genotype A in all other areas. In the region where Asian and Italian immigration occurred, genotypes B, C and D are also described.

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.

Significance of hepatitis B virus genotypes A to E in a cohort of patients with chronic hepatitis B in the Seine Saint Denis District of Paris (France)

The aim of this study was to examine the genetic variability of the hepatitis B virus (HBV) and its significance. HBV genotypes, core promoter and precore mutants were characterized in 109 consecutive patients with biopsy-proven HBV chronic hepatitis. Genotypes A (26.6%), B (12.8%), C (18.3%), D (18.3%), and E (14.7%) indicate a wide genotypic distribution. Patients were from Asia (30.3%), Europe (28.4%), Sub Saharan Africa (23.9%), the Caribbean (10.1%), North Africa (5.5%), and Madagascar (1.8%). HBV genotypes A and D (HBV/A and /D) infected all subgroups except Asian patients. HBV/B or /C were found in 97% of Asian patients, whereas HBV/E only infected sub-Saharan African and Caribbean patients. Differences according to genotypes were: an increased prevalence of anti-HBe antibodies in patients infected with HBV/D (P = 0.003), higher serum transaminases in patients infected with HBV/A and/D (P = 0.043), more severe liver fibrosis in patients infected with HBV/A, /C and/D (P = 0.02). Precore and core promoter mutants were found in 87% of anti-HBe positive patients, and were associated with HBV/D (P = 0.04) and severe liver fibrosis (P = 0.002). It is concluded that HBV genotypes A, B, C, D, and E circulate in the Seine Saint Denis District, reflecting the geographical origin of patients. HBV/A, /C and/D seem to be associated with more severe hepatic disease.

Hepatitis B virus genotyping, core promoter, and precore/core mutations among Afghan patients infected with hepatitis B: A preliminary report

In spite of hepatitis B virus (HBV) vaccination, HBV infection remains an important public health problem worldwide. Although the HBV genotype distribution has been determined in some parts of South Central Asia, no survey has been conducted to determine the HBV genotype in Afghanistan. Twelve Afghan patients infected with HBV living in Afghanistan were enrolled in this study. Partial HBsAg and basic core promoter, precore, and core (BCP/preC/C) regions were amplified and subjected for direct sequencing. In parallel, precore G1896A mutation was also determined by an amplification-created restriction site method. Results revealed HBV genotype D (95% bootstrap value), sub-genotype D1 (98% bootstrap value), and subtype ayw2 in all Afghan isolates. Afghan isolates clustered in a separate branch in the D1 sub-genotype called D1', while supported by 82% bootstrap value. The percentage of intra-genotypic distance among Afghan isolates was 1.05% and inter-genotypic distance with the other genotype D was 2.87% and with other genotypes was 7.50%-11.1%. The wild-type, mixed infection, and precore mutant were found in six, two, and four HBV isolates, respectively. The A1762T/G1764A BCP dual mutation was found in one isolate. Three isolates presented single mutation in the BCP dual mutation region, whereas two showed a novel G1764T mutation. In conclusion, this preliminary study revealed HBV genotype D, sub-genotype D1, and subtype ayw2 of HBV among hepatitis B infected patients from Afghanistan. Further investigation should be carried out.

Classifying genotype F of hepatitis B virus into F1 and F2 subtypes

AIM: To explore the propriety of providing hepatitis B virus (HBV) genotypes F and H with two distinct genotypes.

METHODS: Eleven HBV isolates of genotype F (HBV/F) were recovered from patients living in San Francisco, Japan, Panama, and Venezuela, and their full-length sequences were determined. Phylogenetic analysis was carried out among them along with HBV isolates previously reported.

RESULTS: Seven of them clustered with reported HBV/F isolates in the phylogenetic tree constructed on the entire genomic sequence. The remaining four flocked on another branch along with three HBV isolates formerly reported as genotype H. These seven HBV isolates, including the four in this study and the three reported, had a sequence divergence of 7.3-9.5% from the other HBV/F isolates, and differed by >13.7% from HBV isolates of the other six genotypes (A-E and G). Based on a marked genomic divergence, falling just short of >8% separating the seven genotypes, these seven HBV/F isolates were classified into F2 subtype and the former seven into F1 subtype provisionally. In a pairwise comparison of the S-gene sequences among the 7 HBV/F2 isolates and against 47 HBV/F1 isolates as well as 136 representing the other six genotypes (A-E and G), two clusters separated by distinct genetic distances emerged.

CONCLUSION: Based on these analyses, classifying HBV/F isolates into two subtypes (F1 and F2) would be more appropriate than providing them with two distinct genotypes (F and H).

Hepatitis B virus infection in isolated Afro-Brazilian communities

The prevalence and genotypes of hepatitis B virus (HBV) have distinct geographical distribution. In Brazil, some African-descendants have been maintained as small isolated communities since the slavery period. In this study, HBV infection among these communities of African origin was examined. Individuals (1,058) living in 12 communities were interviewed and serum samples screened for the presence of HBV markers. HBsAg-positive sera were tested for HBV DNA by PCR and positive samples were genotyped by restriction fragment length polymorphism (RFLP). The overall prevalence of HBV infection was 19.8% (95% CI: 17.5-22.3), ranging from 5.5% to 42.4%, depending on the communities studied. Multivariate analysis of risk factors showed that increasing age, family history of hepatitis, and sexual activity were associated significantly with this infection. HBsAg was detected in 23/1,058 (2.2%) individuals. HBV DNA was present in 2/2 of HBeAg-positive serum samples and in 18/21 (85.7%) anti-HBe-positive samples. All HBV isolates belonged to genotype A, subtype Aa. Three RFLP patterns were identified: AI (17 isolates), AIV (1 isolate), and AVI (2 isolates). These findings suggest a common introduction of HBV during the slave trade from Africa to Brazil.

Influence of HLA-DRB1 alleles and HBV genotypes on interferon-α therapy for chronic hepatitis B

AIM: To investigate the influence of HLA-DRB₁ alleles and HBV genotypes on interferon-α therapy for chronic hepatitis B.

METHODS: HLA-DRB1*03, *07, *09, *12, *15 alleles were determined using polymerase chain reaction/sequence specific primer (PCR/SSP) technique in 126 patients with chronic hepatitis B and 76 normal control subjects in Shandong Province, and HBV genotypes were determined by nested-PCR analysis using type-specific primers in 126 patients.

RESULTS: The positivity of HLA-DRB1*07 allele in chronic hepatitis B group was significantly higher than that in normal control group (χ² = 6.33, P < 0.025, RR = 2.37). Among the 126 patients, genotype B was found in 38 (30.2%), genotype C in 69 (54.8%), and mixed genotype (B+C) in 19 (15.0%), genotypes D-F were not found. Among the 46 DRB1*07(+) patients, 7 were responders and 39 were non-responders among them (χ² = 6.71, P < 0.05). The positivity of HLA-DRB1*07 and prevalence of HBV genotype C were significantly higher in non-responders than in responders.

CONCLUSION: High positivities of HLA-DRB1 ^*07 allele and HBV genotype C are closely associated with the lower response to interferon-α therapy for chronic hepatitis B.

Genotypic variability of hepatitis viruses associated with chronic infection and the development of hepatocellular carcinoma

At least five hepatitis viruses are known to date. Infection by enterically transmitted viruses (HAV and HEV) is generally benign compared with the disease caused by parenterally transmitted viruses (HBV, HCV, and HDV). Chronic infection by HBV is common and may evolve to cirrhosis and hepatocellular carcinoma (HCC). Eight HBV genotypes (A-H) have been described, with the South American genotype F being the most divergent. Seven clades of HDV have been described; among them, the South American genotype III is associated to a high frequency of fulminant hepatitis. HCV infection leads to a high rate of chronicity and HCC. From the six HCV genotypes, infection with genotype 1 might have the worst prognostic. Chronic infection by HCV and HBV is the major risk factor for HCC, which occurs, in the majority of the cases, as a consequence of cirrhosis. However, there is growing evidence that some HBV and HCV proteins might contribute to the generation of HCC. Some HBV and HCV variants and specific mutations within the viral genomes might be more frequently associated with the evolution to HCC. Although more studies are needed, emerging evidence indicates that it might be important to address the genetic variability of these viruses and their contribution to the development of HCC.

Molecular epidemiology of hepatitis B virus in Spain: identification of viral genotypes and prediction of antigenic subtypes by limited sequencing

The hepatitis B virus (HBV) genotypes were studied by a line probe assay (LiPA) and by direct sequencing of a 339 nucleotide fragment from the S region of the viral genome in samples from 269 carriers living in Spain, either native to Spain (231) or immigrants from Africa, Asia, and Eastern Europe (38). The sequences were also used to predict the HBV surface antigen (HBsAg) subtype on the basis of the amino acids specified at selected positions of the HBsAg molecule. Agreement between the two genotyping methods was found in most cases (98.1%) and a HBV genotype could be assigned to all samples. The viral groups D/ayw2 (30.1%), D/ayw3 (28.6%), and A/adw2 (21.2%) were prevalent, with an additional participation of the groups D/ayw4 (4.8%), F/adw4q- (1.9%), A/ayw1 (1.9%), and D/adw3 (0.7%), all of them present among the autochthonous carriers. Strains from genotypes B and C were found exclusively among Chinese immigrants. Genotype E strains were found in immigrants from Central Africa and in one patient native of Spain. Point mutations leading to amino acid changes of residues involved in the expression of the HBsAg subtype determinants were found in 12 samples (4.5%). Some mutations would predict the putative novel genotype-subtype associations A/adw4q+, A/ayr, D/ayr, and E/ayw1, while others would suggest the loss of subtype-specific determinants. The finding of HBV strains characteristic for Africa among the autochthonous carriers confirms the emergence of African HBV strains in Spain.

[Hepatitis B and D virus infection within Amerindians ethnic groups in the Brazilian Amazon: epidemiological aspects]

Several studies describe very high prevalence rates of infection and disease of hepatitis B and D within Native American population. This is a review of what has been described among Amerindians of Brazilian Amazon. Some groups show low prevalence rates of HBsAg, whereas, others of the same region reveal high endemic pattern, even among individuals less then 10 years of age. HDV is only found in groups of Amazonas province. Transmission may occur by interfamilial dissemination or sexual contact among young adults. Socio-cultural, genetic, and ecological factors are described as determinants of this unique pattern. Nevertheless, the origin of these two viruses is yet to be disclosed. Amerindians population and their genetic memory are a live experiment, which demands a broad investigation, weighting with modern tools, as molecular biology, the influence of historical, genetic, medical and anthropological factors.

Hepatitis B virus genotypes

Eight genotypes of hepatitis B virus (A-H) are currently recognized, and subgenotypes have recently been described in four of these genotypes (A, B, C and F). The genotypes show a distinct geographical distribution between and even within regions, and are proving to be an invaluable tool in tracing the molecular evolution and patterns and modes of spread of hepatitis B virus. Structural and functional differences between genotypes can influence the severity, course and likelihood of complications, and response to treatment of hepatitis B virus infection and possibly vaccination against the virus. Although the number of studies on these genotypes has increased dramatically during recent years, much remains to be learnt about their full implications.

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

A number of reports have indicated an increased risk of cirrhosis and hepatocellular carcinoma in hepatitis B virus (HBV)-infected individuals carrying HBV e antigen (HBeAg)-negative variants. Although distinct core promoter and precore mutations distributed according to geographical locality and viral genotype have been reported, epidemiological data from South America are still scarce. The prevalences of HBV genotypes and core promoter and precore polymorphisms in 75 HBeAg-negative Argentinean blood donors were surveyed. The observed frequencies of HBV genotypes were 64.0% for genotype F, 17.3% each for genotypes A and D, and 1.3% for genotype C. Genotype F strains were widely distributed and significantly more prevalent in the northern region of the country (P < 0.001). An overall high proportion of a stop codon mutation (UAG) at precore codon 28 (66.7%) was observed. Wild-type codon 28 (UGG) was present in 29.3% of the samples, and the remaining 4.0% of samples had mixed variants. The combination of A at nucleotide (nt) 1762 and G at nt 1764 of the core promoter was found in 58.7% of the samples. The variant profiles--T at nt 1762 and A at nt 1764 or A at nt 1762 and A at nt 1764--were detected in 28.0 and 1.3% of the samples, respectively. The observed core promoter polymorphisms could not be related to the ratio of HBeAg to anti-HBeAg antibody, HBV genotype, or precore codon 28 status. Nevertheless, a clear association of genotype F and a precore stop codon mutation was found (P < 0.05). In conclusion, HBV genotype F and mutant codon 28 strains predominated and were strongly associated in a geographically broad Argentinean blood donor population.

Molecular and serological evaluation of surface antigen negative hepatitis B virus infection in blood donors from Venezuela

Surface antigen negative hepatitis B virus (HBV) infection was evaluated in Venezuela, by molecular characterization of blood samples positive for antibodies to core antigen (anti-HBc) and negative for surface antigen (HBsAg) in blood donors (residual infections). HBV DNA was found in 11/258 samples (4.3%), and was significantly associated with high levels of anti-HBc antibodies (>25 UI/ml, P < 0.05), while no correlation was found between the presence of HBV DNA and the levels of anti-HBs. Synonymous and non-synonymous mutations were found in the HBV surface region (but not vaccine escape mutants) and in the precore/core region (precore mutants in 2/7 samples and 33-45 bp deletions near the N-terminal core region in 4/19 samples). While HBV genotype F prevails among HBsAg positive samples from blood donors in Venezuela, residual infection isolates were mainly genotypes A and D. Phylogenetic analysis of viral surface and core region revealed discrepancies in genotype designation in 6/9 samples, suggesting the presence of mixed infection or recombination. In conclusion, HBV residual infection in Venezuela does not seem to be frequently observed in HBV genotype F. This type of infection is frequently associated with variants exhibiting mutations in the surface gene that might be affecting the correct recognition by commercial tests, with precore mutants and with core internal deletions. These variants do not seem to cause severe liver disease, and on the contrary, were found circulating at low viremia.

Clade analysis and surface antigen polymorphism of hepatitis B virus American genotypes

Eight genotypes (A-H) of hepatitis B virus (HBV) have been described, HBV genotypes F and H being autochthonous to America. HBV genotype F has been classified in four clusters. The objective of this study was to gain insight into the molecular epidemiology of HBV American genotypes, as well as to analyze the genotype-related polymorphism in some functional domains of the surface proteins. The sequences of the S region of 106 isolates genotype F and H were analyzed, out of which 47 isolates genotype F circulated in different Venezuelan populations. Most of the Venezuelan isolates genotype F were grouped in cluster III (n = 39) and 7 in cluster II. One isolate obtained from a blood donor could not be classified in any clade and harbored amino acid substitutions characteristic of a vaccine escape mutant (G145R) and a stop codon in the surface antigen. Amino acid analysis of the PreS and S gene products showed unique genetic characteristics in genotype F and H sequences in some important domains involved in the early steps of infection. Out of 30 available sequences, two complete genome sequences of HBV genotype F from Venezuela were obtained. Phylogenetic analysis of these complete genomes confirmed the presence of four clusters inside genotype F, differing in more than 4% nucleotide divergence. Our extended analysis showed that genotype F clades Ia, III, and IV exhibit a restricted geographic distribution (Central America, the North and the South of South America, respectively) while clades Ib and II are found in all the Americas except in the Northern South America and North America respectively.

Genotype and subtype analyses of hepatitis B virus (HBV) and possible co-infection of HBV and hepatitis C virus (HCV) or hepatitis D virus (HDV) in blood donors, patients with chronic liver disease and patients on hemodialysis in Surabaya, Indonesia

Four subtypes (adw, adr, ayw, and ayr ) and eight genotypes (A to H) of the hepatitis B virus (HBV) have been identified. They appear to be associated with particular geographic distribution, ethnicity, and possibly clinical outcomes. In this study, hepatitis B surface antigen (HBsAg) subtyping and HBV genotyping were carried out on sera obtained from HBsAg-positive HBV carriers, including healthy blood donors; patients with acute hepatitis, chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma; and patients on hemodialysis all located in Surabaya, Indonesia. We report here that all HBV isolates tested in Surabaya belonged to genotype B, with more than 90% of them being classified into subtype adw. Our results also revealed that prevalence of hepatitis C virus (HCV) co-infection among HBV carriers in Surabaya was approximately 10% for healthy blood donors and patients with chronic liver disease, and approximately 60% for patients on maintenance hemodialysis. Interestingly, HBsAg titers were lower in HBV carriers with HCV co-infection than in those without HCV co-infection. We also found that prevalence of hepatitis D virus (HDV) co-infection was < 0.5% among HBV carriers in Surabaya.

[Basis, types and application of DNA arrays in clinical microbiology]

The DNA microarrays or microchips are sets of DNA probes bound to a solid support in a prefixed and regular disposition. The target nucleic acid that can be detected is either DNA or RNA, which is previously labeled with a fluorochrome or a radioactive compound. The main advantage with respect to other molecular biological tools, such as polymerase chain reaction, is that thousands of genes can be detected in a single procedure. The application of the DNA arrays in the field of clinical microbiology is so far scarce. Among the specific applications we can point out: 1. Investigation of bacterial pathogenesis; 2. Analysis of bacterial evolution and molecular epidemiology; 3. Study of the mechanisms of action and resistance to antimicrobial agents and 4. Microbiological diagnostic of the infectious diseases. This methodology is still in an embryonic phase with respect to its application in clinical microbiology. However, it presents a series of advantages that make it very attractive and in the future it may become a valuable tool for the diagnosis of infectious diseases.

Distribution of hepatitis B viral genotypes and mutations in the core promoter and precore regions in acute forms of liver disease in patients from Chiba, Japan

BACKGROUND

Although it has been reported that different hepatitis B virus (HBV) genotypes induce different clinical characteristics in patients with chronic liver diseases (CLD), there have been few reports that have detailed the distribution of HBV genotypes in acute forms of liver disease.

METHODS

HBV genotypes were determined in 61 patients who had acute forms of liver disease (45 had acute self limited hepatitis (AH) and 16 had fulminant hepatitis (FH)) and in 531 patients with CLD, including 19 patients with severe acute exacerbation of CLD. We also analysed the enhancer II, core promoter, and precore region sequences for the presence of mutations.

RESULTS

Expression of genotype B in patients with acute forms of liver disease was significantly greater than in those with CLD (39.3% v 11.7%, respectively; p<0.001). Furthermore, expression of genotype B was significantly greater in patients with FH than in those with AH (62.5% v 31.1%, respectively; p=0.027). The precore mutation A1896 and the core promoter mutation at nt 1753 and 1754 were found more frequently in FH than in AH, and genotype B was predominant in FH regardless of the presence of these mutations.

CONCLUSIONS

HBV genotype B was found more frequently in patients with acute forms of liver disease than in patients with CLD, and more frequently in patients with FH than in those with AH. These results suggest that this HBV genotype may induce more severe liver damage than other viral genotypes, at least in patients from Chiba, Japan.