Complete nucleotide sequence and phylogenetic analyses of hepatitis B virus isolated from two pileated gibbons

Bat hepadnaviruses and the origins of primate hepatitis B viruses

The origin of primate HBV (family Hepadnaviridae) is unknown. Hepadnaviruses are ancient pathogens and may have been associated with old mammalian lineages like bats for prolonged time. Indeed, the genetic diversity of bat hepadnaviruses exceeds that of extant hepadnaviruses in other host orders, suggesting a long evolution of hepadnaviruses in bats. Strikingly, a recently detected New World bat hepadnavirus is antigenically related to HBV and can infect human hepatocytes. Together with genetically diverse hepadnaviruses from New World rodents and a non-human primate, these viruses argue for a New World origin of ancestral orthohepadnaviruses. Multiple host switches of bat and primate viruses are evident and bats are likely sources of ancestral hepadnaviruses acquired by primates.

Full genome characterization and phylogenetic analysis of hepatitis B virus in gibbons and a caretaker in Central Kalimantan, Indonesia

Hepatitis B virus (HBV) from gibbons was characterized, and the possibility of horizontal transmission between gibbons and humans was examined in a gibbon rehabilitation center in Central Kalimantan, Indonesia. Ten gibbons that were positive for the hepatitis B surface antigen (HBsAg) on arrival and 13 caretakers for those gibbons were included in this study. The duration of stay at the rehabilitation center ranged from 1 to 10 years. Serological and molecular analyses were performed. Six gibbons were positive for HBsAg, whereas HBV DNA was detected in all ten of the gibbons sampled. On the other hand, HBsAg was detected in only 1 of the 13 caretakers. HBV samples from seven gibbons and from the one infected human were chosen for complete genome sequencing. A phylogenetic analysis revealed that the cluster of gibbon strains in this study was distinct from strains previously reported from other countries. In the pre-S1 region, we found a unique amino acid residue substitution (P89K), three insertions between T87 and L88 in the genomes of three gibbons, and a 33-nucleotide deletion at the start of pre-S1 that is common in non-human primates. The caretaker sample was identified as HBV subgenotype B3, the most common type in Indonesia. For the complete HBV sequences, the similarity between gibbons in this study and other non-human primate and human HBV isolates was 90–91.9 % and 85.5–89.6 %, respectively. In conclusion, the gibbon HBV genotype was influenced by geographic location and species. To the best of our knowledge, this is the first report characterizing the HBV genes and genomes of indigenous gibbons in Indonesia.

Theories about evolutionary origins of human hepatitis B virus in primates and humans

Introduction

The human hepatitis B virus causes acute and chronic hepatitis and is considered one of the most serious human health issues by the World Health Organization, causing thousands of deaths per year. There are similar viruses belonging to the Hepadnaviridae family that infect non-human primates and other mammals as well as some birds. The majority of non-human primate virus isolates were phylogenetically close to the human hepatitis B virus, but like the human genotypes, the origins of these viruses remain controversial. However, there is a possibility that human hepatitis B virus originated in primates. Knowing whether these viruses might be common to humans and primates is crucial in order to reduce the risk to humans.

Objective

To review the existing knowledge about the evolutionary origins of viruses of the Hepadnaviridae family in primates.

Methods

This review was done by reading several articles that provide information about the Hepadnaviridae virus family in non-human primates and humans and the possible origins and evolution of these viruses.

Results

The evolutionary origin of viruses of the Hepadnaviridae family in primates has been dated back to several thousand years; however, recent analyses of genomic fossils of avihepadnaviruses integrated into the genomes of several avian species have suggested a much older origin of this genus.

Conclusion

Some hypotheses about the evolutionary origins of human hepatitis B virus have been debated since the ‘90s. One theory suggested a New World origin because of the phylogenetic co-segregation between some New World human hepatitis B virus genotypes F and H and woolly monkey human hepatitis B virus in basal sister-relationship to the Old World non-human primates and human hepatitis B virus variants. Another theory suggests an Old World origin of human hepatitis B virus, and that it would have been spread following prehistoric human migrations over 100,000 years ago. A third theory suggests a co-speciation of human hepatitis B virus in non-human primate hosts because of the proximity between the phylogeny of Old and New World non-human primate and their human hepatitis B virus variants. The importance of further research, related to the subject in South American wild fauna, is paramount and highly relevant for understanding the origin of human hepatitis B virus.

Prevalence and phylogenetic analysis of hepatitis B virus among nonhuman primates in Taiwan

Hepatitis B virus (HBV) is a public health problem worldwide, and apart from infecting humans, HBV has been found in nonhuman primates. This study investigated the prevalence and phylogenetic analysis of hepatitis B virus (HBV) and hepatitis D virus (HDV) among nonhuman primates in Taiwan, an area where human HBV remains endemic. Serum samples from 286 captive nonhuman primates (i.e., 32 great apes [Pan troglodytes and Pongo pygmaeus], 42 gibbons [Hylobates sp. and Nomascus sp.], and 212 Cercopithecidae monkeys) were collected and tested for the presence of HBV- and HDV-specific serologic markers. None of the Cercopithecidae monkeys were reactive against serologic markers of HBV. In contrast, 21.9% (7/32) of great apes and 40.5% (17/42) of gibbons tested positive for at least one serologic marker of HBV. Of these, five gibbons were chronic HBV carriers, characterized by presence of HBV DNA and hepatitis B surface antigen in the serum. HBV DNA was also detected in the saliva of three of the chronic carries. None of these HBV carrier gibbons exhibited symptoms or significant change in serum clinical chemistry related to HBV infection. Phylogenetic analysis of the complete HBV genome revealed that gibbon viruses clustered with other HBV isolates of great apes and gibbons from Southeast Asia and separately from human-specific HBV. None of the HBV-infected animals were reactive against HDV. These findings indicate that HBV found in these animals is indigenous to their respective hosts and might have been introduced into Taiwan via the direct import of infected animals from Southeast Asia. To reduce the horizontal and vertical transmission of HBV in captive animals, the HBV carriers should be kept apart from uninfected animals.

Virologic characteristics of hepatitis B virus in patients infected via maternal-fetal transmission

AIM: To determine whether HBV with the same characteristics causes dissimilar mutations in different hosts.

METHODS: Full-length HBV genome was amplified and linked with pMD T18 vector. Positive clones were selected by double-restriction endonuclease digestion (EcoRI and HindIII) and PCR. Twenty seven clones were randomly selected from an asymptomatic mother [at two time points: 602 (1 d) and 6022 (6 mo)] and her son [602 (S)], and the phylogenetic and mutational analysis was performed using BioEditor, Clustal X and MEGA software. Potential immune epitopes were determined by the Stabilized Matrix Method (SMM), SMM-Align Method and Emini Surface Accessibility Prediction.

RESULTS: All of the 27 sequences were genotype C, the divergence between the mother and son was 0%-0.8%. Compared with another 50 complete sequences of genotype C, the mother and her son each had 13 specific nucleotides that differed from the other genotype C isolates. AA 1-11 deletion in preS1 was the dominant mutation in the mother (14/18). The 1762T/1764A double mutation existed in all clones of the mother, 3 of them were also coupled with G1896A mutation, but none were found in the son. 17 bp deletion starting at nucleotide 2330 was the major mutation (5/9) in the son, which caused seven potential HLA class I epitopes and one B cell epitope deletion, and produced a presumptive new start codon, downstream from the original one of the P gene.

CONCLUSION: The HBV strain in the son came from his mother, and discrepant mutation occurred in the mother and her son during infection.

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.

Frequent infection of Hylobates pileatus (pileated gibbon) with species-associated variants of hepatitis B virus in Cambodia

As well as being distributed widely in human populations, hepatitis B virus (HBV) infections occur frequently in chimpanzee, gibbon and other ape populations in sub-Saharan Africa and South-East Asia. To investigate the frequency and genetic relationships of HBV infecting gibbons in Cambodia, pileated gibbons (Hylobates pileatus) that were originally wild-caught were screened for surface antigen. Twelve of 26 (46 %) were positive, of which 11 were positive for HBV DNA. Phylogenetic analysis of complete genome sequences revealed two distinct genetic groups in the gibbon/orangutan clade. Three were similar to previously described variants infecting H. pileatus in Thailand and eight formed a distinct clade, potentially representing distinct strains of HBV circulating in geographically separated populations in South-East Asia. Because of the ability of HBV to cross species barriers, large reservoirs of infection in gibbons may hamper ongoing attempts at permanent eradication of HBV infection from human populations in South-East Asia through immunization.