A Retrospective Survey of Rodent-borne Viruses in Rural Populations of Brazilian Amazon.

INTRODUCTION: The Amazon tropical rainforest has the most dense and diverse ecosystem worldwide. A few studies have addressed rodent-borne diseases as potential hazards to humans in this region. METHODS: A retrospective survey was conducted using enzyme-linked immunosorbent assay for detecting mammarenavirus and orthohantavirus antibodies in 206 samples collected from rural settlers of the Brazilian Western Amazonian region. RESULTS: Six (2.91%) individuals in the age group of 16 to 36 years were found to possess antibodies against mammarenavirus. CONCLUSION: Evidence of previous exposure to mammarenavirus in the rural population points to its silent circulation in this region.

Orthohantavirus Isolated in Reservoir Host Cells Displays Minimal Genetic Changes and Retains Wild-Type Infection Properties.

: Orthohantaviruses are globally emerging zoonotic pathogens. While the reservoir host role of several rodent species is well-established, detailed research on the mechanisms of host-othohantavirus interactions has been constrained by the lack of an experimental system that is able to effectively replicate natural infections in controlled settings. Here we report the isolation, and genetic and phenotypic characterization of a novel Puumala orthohantavirus (PUUV) in cells derived from its reservoir host, the bank vole. The isolation process resulted in cell culture infection that evaded antiviral responses, persisted cell passaging, and had minor viral genome alterations. Critically, experimental infections of bank voles with the new isolate resembled natural infections in terms of viral load and host cell distribution. When compared to an attenuated Vero E6 cell-adapted PUUV Kazan strain, the novel isolate demonstrated delayed virus-specific humoral responses. A lack of virus-specific antibodies was also observed during experimental infections with wild-type PUUV, suggesting that delayed seroconversion could be a general phenomenon during orthohantavirus infection in reservoir hosts. Our results demonstrate that orthohantavirus isolation on cells derived from a vole reservoir host retains wild-type infection properties and should be considered the method of choice for experimental infection models to replicate natural processes.

Orthohantavirus pulmonary syndrome in Santa Cruz and Tarija, Bolivia, 2018.

INTRODUCTION: Orthohantaviruses are still a significant public health threat in endemic countries, with high case fatality rates (CFR). In Bolivia, the reporting of small outbreaks occurred until 2012. The findings of 40 laboratory-confirmed cases diagnosed in two departments are reported herein. METHODS: This was an observational, retrospective and cross-sectional study. Data on laboratory-confirmed cases in 2018 were collected from the hospitals and departmental health services (SEDES) of Santa Cruz and Tarija. An ELISA was used for the detection of IgM antibody to hantavirus in the patient blood samples. RESULTS: Forty patients were IgM-positive. The median age of the patients was 24 years (interquartile range 19-41 years) and 72.5% were male. All patients were hospitalized; 57.5% were admitted to the intensive care unit and had cardiopulmonary compromise, with 83% of these presenting acute respiratory distress syndrome and 89.5% of these requiring mechanical ventilation. Six patients died (CFR 15%). Patients <15 or >60 years old were more prone to die (odds ratio 10.33, 95% confidence interval 1.411-75.694), as were those with comorbidities (odds ratio 16.5, 95% confidence interval 1.207-225.540). CONCLUSIONS: Orthohantavirus infections were associated with a high CFR. These cases occurred in areas with eco-epidemiological conditions facilitating viral transmission, including the presence of rodents, as well as the risk of spillover to humans due to social, environmental, and occupational factors.

A Retrospective Survey of Rodent-borne Viruses in Rural Populations of Brazilian Amazon

Abstract INTRODUCTION: The Amazon tropical rainforest has the most dense and diverse ecosystem worldwide. A few studies have addressed rodent-borne diseases as potential hazards to humans in this region. METHODS: A retrospective survey was conducted using enzyme-linked immunosorbent assay for detecting mammarenavirus and orthohantavirus antibodies in 206 samples collected from rural settlers of the Brazilian Western Amazonian region. RESULTS: Six (2.91%) individuals in the age group of 16 to 36 years were found to possess antibodies against mammarenavirus. CONCLUSION: Evidence of previous exposure to mammarenavirus in the rural population points to its silent circulation in this region.

Discovery of a highly divergent hepadnavirus in shrews from China.

Limited sampling means that relatively little is known about the diversity and evolutionary history of mammalian members of the Hepadnaviridae (genus Orthohepadnavirus). An important case in point are shrews, the fourth largest group of mammals, but for which there is limited knowledge on the role they play in viral evolution and emergence. Here, we report the discovery of a novel shrew hepadnavirus. The newly discovered virus, denoted shrew hepatitis B virus (SHBV), is divergent to be considered a new species of Orthohepadnavirus. Phylogenetic analysis revealed that these viruses were usually most closely related to TBHBV (tent-making bat hepatitis B virus), known to be able to infect human hepatocytes, and had a similar genome structure, although SHBV fell in a more basal position in the surface protein phylogeny. In sum, these data suggest that shrews are natural hosts for hepadnaviruses and may have played an important role in their long-term evolution.

A Novel Orthohepadnavirus Identified in a Dead Maxwell's Duiker (Philantomba maxwellii) in Taï National Park, Côte d'Ivoire.

New technologies enable viral discovery in a diversity of hosts, providing insights into viral evolution. We used one such approach, the virome capture sequencing for vertebrate viruses (VirCapSeq-VERT) platform, on 21 samples originating from six dead Maxwell's duikers (Philantomba maxwellii) from Taï National Park, Côte d'Ivoire. We detected the presence of an orthohepadnavirus in one animal and characterized its 3128 bp genome. The highest viral copy numbers were detected in the spleen, followed by the lung, blood, and liver, with the lowest copy numbers in the kidney and heart; the virus was not detected in the jejunum. Viral copy numbers in the blood were in the range known from humans with active chronic infections leading to liver histolytic damage, suggesting this virus could be pathogenic in duikers, though many orthohepadnaviruses appear to be apathogenic in other hosts, precluding a formal test of this hypothesis. The virus was not detected in 29 other dead duiker samples from the Côte d'Ivoire and Central African Republic, suggesting either a spillover event or a low prevalence in these populations. Phylogenetic analysis placed the virus as a divergent member of the mammalian clade of orthohepadnaviruses, though its relationship to other orthohepadnaviruses remains uncertain. This represents the first orthohepadnavirus described in an artiodactyl. We have tentatively named this new member of the genus Orthohepadnavirus (family Hepadnaviridae), Taï Forest hepadnavirus. Further studies are needed to determine whether it, or some close relatives, are present in a broader range of artiodactyls, including livestock.

Orthohantaviruses belonging to three phylogroups all inhibit apoptosis in infected target cells.

Orthohantaviruses, previously known as hantaviruses, are zoonotic viruses that can cause hantavirus pulmonary syndrome (HPS) and hemorrhagic fever with renal syndrome (HFRS) in humans. The HPS-causing Andes virus (ANDV) and the HFRS-causing Hantaan virus (HTNV) have anti-apoptotic effects. To investigate if this represents a general feature of orthohantaviruses, we analysed the capacity of six different orthohantaviruses - belonging to three distinct phylogroups and representing both pathogenic and non-pathogenic viruses - to inhibit apoptosis in infected cells. Primary human endothelial cells were infected with ANDV, HTNV, the HFRS-causing Puumala virus (PUUV) and Seoul virus, as well as the putative non-pathogenic Prospect Hill virus and Tula virus. Infected cells were then exposed to the apoptosis-inducing chemical staurosporine or to activated human NK cells exhibiting a high cytotoxic potential. Strikingly, all orthohantaviruses inhibited apoptosis in both settings. Moreover, we show that the nucleocapsid (N) protein from all examined orthohantaviruses are potential targets for caspase-3 and granzyme B. Recombinant N protein from ANDV, PUUV and the HFRS-causing Dobrava virus strongly inhibited granzyme B activity and also, to certain extent, caspase-3 activity. Taken together, this study demonstrates that six different orthohantaviruses inhibit apoptosis, suggesting this to be a general feature of orthohantaviruses likely serving as a mechanism of viral immune evasion.

Development of a serosurveillance assay for detection of Necoclí virus exposure.

Hantavirus cardiopulmonary syndrome (HPS) has gained importance in Latin America as an emerging disease, with reports of about 4000 HPS cases; however, this is probably an underestimate because of limited surveillance programs and diagnostic tools to confirm HPS. In order to address this issue and develop better serosurveillance capability, we evaluated three recombinant peptides from the Necoclí virus (NECV) nucleocapsid in antibody-capture ELISA. We cloned and expressed antigens representing the whole NECV nucleocapsid protein (NECV-rN), the immunodominant domain (NECV-rN100), and a serospecific domain (NECV-rN428), and then we compared these antigens in ELISA to detect IgG antibodies to NECV in human sera. We evaluated human sera collected during two epidemiological studies from the area where NECV was discovered. The first group included 609 sera from healthy individuals, and the second one included 89 samples from patients with undifferentiated febrile illness. In these two groups, hantavirus infection had previously been determined by the presence of IgG to Maciel virus (MCLV), a hantavirus closely related to NECV. The number of IgG-positive sera was higher using the Necoclí ELISA with the rN100 protein, which detected antibodies in a higher percentage of healthy individuals, 129/609 (21.2%), as well as in febrile patients, 11/89 (12.3%). In contrast, using MCLV ELISA, 8 of 609 (1.3%) and 4 of 89 (4.5%) samples from healthy and febrile patients, respectively, were seropositive. The agreement between the NECV and MCLV ELISA assays was ≥ 82.3%; however, the kappa indices were weak but statistically significant for rN (0.251 CI; 0.138-0.365) and rN100rN (0.153 CI; 0.084-0.223). The weak kappa indices were attributed to decreased MCLV ELISA assay sensitivity. These results suggest that NECV rN and rN100 have increased specificity and could be further validated for improved diagnosis of hantavirus infections.

Genetic diversity of bat orthohepadnaviruses in China and a proposed new nomenclature.

The orthohepadnaviruses, which include the major human pathogen hepatitis B virus, exist in a wide range of hosts. Since 2013, a large group of orthohepadnaviruses has been identified in bats worldwide and classified as 4 species within the genus Orthohepadnavirus. To further investigate orthohepadnaviruses in the Chinese bat population, 554 archived bat samples from 20 colonies covering 3 southern provinces were screened with results showing that 9 (1.6%) were positive. A systematic phylogenetic analysis has indicated the need for a new nomenclature for bat hepatitis B virus-like viruses: BtHBV, with the addition of 3 new species, one being divided into 6 genotypes. Viruses identified here shared 9.0-19.2% full genome divergence and classified into 3 different genotypes. This study illustrates the genetic diversity of orthohepadnaviruses in the Chinese bat population, and emphasizes need for further investigation of their public health significance.

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.

Hepatitis virus in long-fingered bats, Myanmar.

During an analysis of the virome of bats from Myanmar, a large number of reads were annotated to orthohepadnaviruses. We present the full genome sequence and a morphological analysis of an orthohepadnavirus circulating in bats. This virus is substantially different from currently known members of the genus Orthohepadnavirus and represents a new species.

Prevalence of a virus similar to human hepatitis B virus in swine.

BACKGROUND: The objective of this study is to established evidence of the existence of a novel member of the hepadnavirus family endemic in swine. Temporarily this virus was designated as swine hepatitis B virus (SHBV). This SHBV can be detected by using human hepatitis B virus diagnostic kits including ELISA, immunohistochemical staining, and transmission electron microscopy (TEM). Also seroprevalence of pig farms in Beijing, China, and pathological features of SHBV infection was determined. RESULTS: Screened result shows that overall prevalence of HBsAg was 24.8%, closed to that of anti-HBsAg, whereas HBeAg and anti-HBe were barely detectable. The distribution of HBsAg and HBcAg was examined by immunohistochemistry of liver samples. Typical hepatitis pathological change, such as spotty parenchymal cell degeneration, necrosis of hepatocytes and proliferation of fibrous connective tissue were observed during histopathological analysis. Analysis of HBsAg-positive serum with TEM revealed two morphologic forms, 20 nm and 40 nm sized particles, similar to small spherical and Danes particles of HBV. Observation of the ultrastructure of the liver also found HBV-like particles in the nucleus of hepatocytes. CONCLUSION: Our research result implies that SHBV could be a causative agent of swine. The discovery of SHBV will unveil novel evolutionary aspects of hepatitis and provides new information for further hepadnavirus research.

Identification of interspecies recombination among hepadnaviruses infecting cross-species hosts.

Members of the family Hepadnaviridae are divided into two genera, Orthohepadnavirus (from mammalian) and Avihepadnavirus (from avian). Recombination had been found to occur among human hepatitis B virus (HBV) strains of different genotypes, or between hepadnavirus strains from human and nonhuman primate. To reach a comparatively complete inspection of interspecies recombination events among hepadnavirus strains from various hosts, 837 hepadnavirus complete genome sequences from human and 112 from animals were analyzed by using fragment typing to scan for potential interspecies recombinants. Further bootscanning and phylogenetic analyses of the potential recombinants revealed six genome sequences as interspecies recombinants. Interspecies recombination events were found to occur among HBV strains from human and nonhuman primates, from gibbons of different genera, from chimpanzee and an unknown host, and between two avian hepadnavirus strains from birds of different subfamilies, which was identified for the first time. HBV interspecies recombinants were found to have recombination hot spots similar to that of human HBV intergenotype recombinants, breakpoints frequently locating near gene boundaries. Interspecies recombination found in this study may alter current views on hepadnavirus host specificity.

Hepatitis B virus taxonomy and hepatitis B virus genotypes.

Hepatitis B virus (HBV) is a member of the hepadnavirus family. Hepadnaviruses can be found in both mammals (orthohepadnaviruses) and birds (avihepadnaviruses). The genetic variability of HBV is very high. There are eight genotypes of HBV and three clades of HBV isolates from apes that appear to be additional genotypes of HBV. Most genotypes are now divided into subgenotypes with distinct virological and epidemiological properties. In addition, recombination among HBV genotypes increases the variability of HBV. This review summarises current knowledge of the epidemiology of genetic variability in hepadnaviruses and, due to rapid progress in the field, updates several recent reviews on HBV genotypes and subgenotypes.

Universal primers for real-time amplification of DNA from all known Orthohepadnavirus species.

BACKGROUND: The family of Hepadnaviridae is made up of members infecting birds (genus Avihepadnavirus) or mammals (genus Orthohepadnavirus). Hepatitis B virus (HBV), the hepadnavirus infecting humans, can be divided into the seven genotypes A-G. By definition, genotypes differ by more than 8% at the nucleotide level. However, some genotypes differ by more than 14% from others. OBJECTIVES: The diversity of HBV genotypes necessitates great care in primer design to find primers suitable for routine diagnostic procedures that are highly conserved. Our aim was to find a target sequence on the HBV genome that is highly conserved among all known orthohepadnaviruses, to avoid false-negative polymerase chain reaction (PCR) results due to uncommon variants of HBV. METHODS: Using an alignment of 177 genomes of orthohepadnaviruses from GenBank, we selected a primer pair from a highly conserved region, corresponding to hydrophobic transmembrane domains of the major surface protein of HBV. RESULTS: The primer pair chosen was suitable to amplify genome sequences from HBV and to the genetically most distant woodchuck hepatitis virus in real-time PCR using the LightCycler, Roche. Moreover, the primers were suitable for accurate quantitation of both viral genomes over a range from 100 to 10(10) genomes/ml. CONCLUSION: The described primers are useful for reliable detection and accurate quantitation of all known hepadnaviral genomes and may be used for the search for unknown orthohepadnaviruses.

A new hepadnavirus endemic in arctic ground squirrels in Alaska.

We present evidence for a novel member of the hepadnavirus family that is endemic in wild arctic ground squirrels (Spermophylus parryi kennicotti) in Alaska. This virus, designated arctic squirrel hepatitis virus (ASHV), was initially detected in the livers of animals bearing large hepatic nodules by nucleic acid hybridization with hepadnavirus probes and in plasma by cross-reactivity with antibodies to hepadnavirus surface and core antigens. The complete nucleotide sequence of the 3,302-bp-long ASHV genome was determined and compared with those of ground squirrel hepatitis virus (GSHV) and woodchuck hepatitis virus (WHV); all sequences were organized into four open reading frames, designated pre-C/C, pre-S/S, pol, and X. Despite roughly equivalent variability among the three rodent hepadnaviruses (around 16% base and 19% amino acid exchanges), ASHV appeared to be more closely related to GSHV than to WHV in phylogenetic analysis. Accordingly, preliminary studies of the pathology of ASHV infection suggested that ASHV may be a less efficient oncogenic agent than WHV. About one-third of aged animals maintained in captivity, including virus-infected as well as uninfected squirrels, developed large liver nodules, consisting of hepatocellular adenomas or carcinomas or nonmalignant lesions characterized by drastic microvesicular steatosis. ASHV-infected arctic ground squirrels may serve as a new model with which to analyze the contribution of hepadnavirus- and host-specific determinants to liver pathology and tumorigenesis.