Development and Characterization of Efficient Cell Culture Systems for Genotype 1 Hepatitis E Virus and Its Infectious cDNA Clone.

Hepatitis E virus (HEV) is a major cause of acute viral hepatitis globally. Genotype 1 HEV (HEV-1) is responsible for multiple outbreaks in developing countries, causing high mortality rates in pregnant women. However, studies on HEV-1 have been hindered by its poor replication in cultured cells. The JE04-1601S strain recovered from a Japanese patient with fulminant hepatitis E who contracted HEV-1 while traveling to India was serially passaged 12 times in human cell lines. The cell-culture-generated viruses (passage 12; p12) grew efficiently in human cell lines, but the replication was not fully supported in porcine cells. A full-length cDNA clone was constructed using JE04-1601S_p12 as a template. It was able to produce an infectious virus, and viral protein expression was detectable in the transfected PLC/PRF/5 cells and culture supernatants. Consistently, HEV-1 growth was also not fully supported in the cell culture of cDNA-derived JE04-1601S_p12 progenies, potentially recapitulating the narrow tropism of HEV-1 observed in vivo. The availability of an efficient cell culture system for HEV-1 and its infectious cDNA clone will be useful for studying HEV species tropism and mechanisms underlying severe hepatitis in HEV-1-infected pregnant women as well as for discovering and developing safer treatment options for this condition.

Persistent infection with a rabbit hepatitis E virus created by a reverse genetics system.

Rabbit hepatitis E virus (HEV) is a novel zoonotic infectious agent. Although a cell culture system to grow the virus has been established, there is currently no reverse genetics system for generating the virus. In this study, capped genomic rabbit HEV RNAs generated by in vitro transcription were transfected into PLC/PRF/5 cells, and the recovered viruses were subsequently passaged in the cells. The cell culture supernatant was capable of infecting rabbits negative for anti-HEV antibody by intravenous and oral inoculation, indicating that rabbit HEV generated by the reverse genetics system is infectious. Genome-wide analyses indicated that no nucleotide sequence change occurred in the virus genomes that were recovered from the cell culture supernatant after transfection and passaged one time or in the virus genomes recovered from faecal specimens of the infected rabbits. Ribavirin, a broad-spectrum anti-viral inhibitor, efficiently abrogated virus replication ex vivo and transiently suppressed the virus growth in the virus-infected rabbits, suggesting that this reagent is a candidate for therapeutic treatment. In addition, transmission of rabbit HEV to rabbits caused persistent infection, suggesting that the virus-infected rabbit could be an animal model for virus-induced hepatitis. The infectious rabbit HEV produced by a reverse genetics system would be useful to elucidate the mechanisms of HEV replication and the pathogenesis of viral hepatitis.

Antiviral candidates against the hepatitis E virus (HEV) and their combinations inhibit HEV growth in in vitro.

Hepatitis E is a global public health problem. Ribavirin (RBV) and pegylated interferon alpha are currently administered to cure hepatitis E. Recently, in combination with RBV, sofosbuvir (SOF), an anti-hepatitis C virus nucleotide analog, is also given to patients with chronic hepatitis E. However, this combinatorial therapy sometimes fails to achieve a sustained virological response. In this study, we used 27 antiviral compounds, including 15 nucleos(t)ide analogs, for in vitro screening against a genotype 3 HEV strain containing a Gaussia luciferase reporter. RBV, SOF, 2'-C-methyladenosine, 2'-C-methylcytidine (2CMC), 2'-C-methylguanosine (2CMG), and two 4'-azido nucleoside analogs (R-1479 and RO-9187) suppressed replication of the reporter genome, while only RBV, SOF, 2CMC and 2CMG inhibited the growth of genotype 3 HEV in cultured cells. Although 2CMG and RBV (2CMG/RBV) exhibited a synergistic effect while SOF/RBV and 2CMC/RBV showed antagonistic effects on the reporter assay, these three nucleos(t)ide analogs acted additively with RBV in inhibiting HEV growth in cultured cells. Furthermore, SOF and 2CMG, with four interferons (IFN-α2b, IFN-λ1, IFN-λ2 and IFN-λ3), inhibited HEV growth efficiently and cleared HEV in cultured cells. These results suggest that, in combination with RBV or interferons, SOF and 2CMG would be promising bases for developing anti-HEV nucleos(t)ide analogs.

Screening of novel drugs for inhibiting hepatitis E virus replication.

Hepatitis E, which is caused by hepatitis E virus (HEV), is generally a self-limiting, acute, and rarely fatal disease. It is sometimes fulminant and lethal, especially during pregnancy. Indeed, it occasionally takes a chronic course in immunocompromised individuals. To cure hepatitis E patients, the broad-spectrum antivirals (ribavirin and pegylated interferon α) are used. However, this treatment is insufficient and unsafe in some patients due to embryoteratogenic effects, leukopenia, and thrombocytopenia. In this study, we constructed an HEV replication reporter system with Gaussia luciferase for comprehensively screening anti-HEV drug candidates, and developed a cell-culture system using cells robustly producing HEV to validate the efficacy of anti-HEV drug candidates. We screened anti-HEV drug candidates from United States Food and Drug Administration-approved drugs using the established HEV replication reporter system, and investigated the selected candidates and type III interferons (interferon λ1-3) using the cell-culture system. In conclusion, we constructed an HEV replicon system for anti-HEV drug screening and a novel cell-culture system to strictly evaluate the replication-inhibitory activities of the obtained anti-HEV candidates. Our findings suggested that interferon λ1-3 might be effective for treating hepatitis E.

The identification and characterization of novel rat hepatitis E virus strains in Bali and Sumbawa, Indonesia.

All three genetic groups of ratHEV have been found in Indonesia, suggesting the presence of additional variants of ratHEV in unexamined areas of Indonesia. A total of 242 wild rats were captured in Bali and Sumbawa, Indonesia, during 2014-2016. Among them, 4.1% were seropositive for anti-ratHEV IgG and two (0.8%) had detectable ratHEV RNA: ratESUMBAWA-140L and ratEBali2016D-047L, sharing 84.9-85.4% and 86.9-92.1% nucleotide identity with the reported G2 strains, respectively. The provisional criteria supported the notion that the ratEBali2016D-047L and ratESUMBAWA-140L strains were novel G2 variants. These results suggested the spatial distribution of further divergent ratHEV strains in Indonesia.

An analysis of two open reading frames (ORF3 and ORF4) of rat hepatitis E virus genome using its infectious cDNA clones with mutations in ORF3 or ORF4.

Rat hepatitis E virus (ratHEV) genome has four open reading frames (ORFs: ORF1, ORF2, ORF3 and ORF4). The functions of ORF3 and ORF4 are unknown. An infectious cDNA clone (pUC-ratELOMB-131L_wt, wt) and its derivatives including ORF3-defective (ΔORF3) and ORF4-defective (ΔORF4) mutants, were constructed and their full-length RNA transcripts transfected into PLC/PRF/5 cells. ΔORF3 replicated as efficiently as wt in cells. However, ≤1/1000 of the number of progenies were detectable in the culture supernatant of ΔORF3-infected cells compared with wt-infected cells. ORF4 protein was not detectable in ratHEV-infected cells or in the liver tissues of ratHEV-infected rats. No marked differences were noted between wt and ΔORF4 regarding the viral replication and protein expression. ORF3 mutants with proline-to-leucine mutations at amino acids (aa) 93, 96 and/or 98 in ORF3 were constructed and transfected into PLC/PRF/5 cells. Wt and an ORF3 mutant with leucine at aa 98 (ORF3-L98) replicated efficiently (density 1.15-1.16 g/cm3), while ORF3-L93 + L96 exhibited a decreased viral release and banded at 1.26-1.27 g/cm3, similar to ΔORF3. In conclusion, the ORF3 protein, especially its proline residues at aa 93 and 96, is essential for the release of membrane-associated ratHEV particles, and ORF4 is unnecessary for the replication of ratHEV.

Distinct changing profiles of hepatitis A and E virus infection among patients with acute hepatitis in Mongolia: The first report of the full genome sequence of a novel genotype 1 hepatitis E virus strain.

In January 2012, Mongolia started a hepatitis A vaccination program, which has not yet been evaluated. The first occurrence of autochthonous acute hepatitis E in 2013, caused by genotype 4 hepatitis E virus (HEV), suggests the need for a routine study to monitor its prevalence. One hundred fifty-four consecutive patients who were clinically diagnosed with acute hepatitis between 2014 and 2015 in Ulaanbaatar, Mongolia were studied. By serological and molecular testing followed by sequencing and phylogenetic analysis, only one patient (0.6%) was diagnosed with acute hepatitis A, caused by genotype IA hepatitis A virus (HAV), and 32 (20.8%) patients were diagnosed with acute hepatitis E, caused by genotype 1 HEV. The 32 HEV isolates obtained in this study shared 99.5-100% nucleotide identity and were grouped into a cluster separated from those of subtypes 1a to 1f. Upon comparison of p-distances over the entire genome, the distances between one representative HEV isolate (MNE15-072) and 1a-1f strains were 0.071-0.137, while those between 1b and 1c were 0.062-0.070. In conclusion, the prevalence of acute hepatitis A has decreased in Mongolia since the start of the vaccination program, while the monophyletic genotype 1 HEV strain of a probably novel subtype has been prevalent.

Full-length genome of a novel genotype 3 hepatitis E virus strain obtained from domestic pigs in Japan.

Hepatitis E virus (HEV) causes acute or chronic hepatitis in humans and can be transmitted via the fecal-oral route. Pigs are one of the main reservoirs for this infection. Sixty pigs, 4-5 months of age, on a swine herd in Japan had detectable anti-HEV IgG antibodies, and five (8.3%) of them had ongoing infection of genotype 3 HEV. Five HEV strains obtained from the viremic pigs shared 98.8-100% nucleotide identity, and one representative strain (swHE1606845), whose entire genomic sequence was determined in this study, differed by 14.1-19.6% from the reported HEV strains of subtypes 3a-3k and by 14.7-19.1% from other genotype 3 HEV strains whose subtypes have not yet been assigned. swHE1606845 showed a higher nucleotide p-distance value of ≥0.143 with the genotype 3 HEV strains of subtypes 3a-3k and ≥0.152 with other genotype 3 strains of unassigned subtypes. A SimPlot analysis revealed a lack of recombination events. These results indicate that swHE1606845 is a candidate member of a novel subtype of genotype 3. Further efforts to identify the swHE1606845-like novel strain are warranted to clarify the origin of this strain and to determine the complete nucleotide sequences of two additional swHE1606845-like strains for assigning a new subtype.

Production of monoclonal antibodies against the ORF3 protein of rat hepatitis E virus (HEV) and demonstration of the incorporation of the ORF3 protein into enveloped rat HEV particles.

Eight murine monoclonal antibodies (MAbs) against a synthetic peptide corresponding to the C-terminal 15-amino-acid portion of the ORF3 protein of rat hepatitis E virus (ratHEV) were produced and characterized. Immunofluorescence assays using the anti-ratHEV ORF3 MAbs revealed the accumulation of ORF3 protein in the cytoplasm of PLC/PRF/5 cells transfected with ORF3-expressing plasmids or inoculated with cell-culture-generated ratHEV strains. Anti-ORF3 MAbs could capture ratHEV particles in culture supernatant and serum following treatment with 0.5 % deoxycholate, but not those without prior detergent treatment or fecal ratHEV particles. Following treatment with 0.5 % deoxycholate and 0.5 % trypsin, the buoyant density of ratHEV particles in culture supernatant with ORF3 protein on the surface shifted from 1.15 g/cm3 to 1.26 g/cm3 in a sucrose gradient; the resulting particles were capturable by an anti-ORF2 MAb but not by an anti-ORF3 MAb. This indicates that the ORF3 protein (at least its C-terminal portion) is incorporated into the enveloped ratHEV virions released from infected cells but that it is not found in the virions in the feces, supporting the hypothesis that the ratHEV ORF3 protein is associated with the egress of virions from infected cells, similar to human HEV, despite the fact that the ratHEV ORF3 protein lacks a PSAP amino acid motif.

Analysis of adaptive mutations selected during the consecutive passages of hepatitis E virus produced from an infectious cDNA clone.

To characterize the genomic mutations of hepatitis E virus (HEV) during consecutive passages associated with adaptation to growth in cell culture, a cloned genotype 3 HEV [pJE03-1760F/wt, starting virus (SV)] was passaged 10 times in A549 cells, and the entire genomic sequence of the passage 10 (P10) progeny was determined. Compared to SV, P10 virus possessed two non-synonymous (T2808C and A5054G) and four synonymous mutations (C1213T, T2557C, C3118T and C4435T) in the ORF1. Full-length infectious cDNA clones with a single, double (T2808C and A5054G), or all six mutations, identical to P10, were constructed, and their replication capacity was compared. Four (C1213T, T2557C, T2808C and A5054G) of the six viruses with a single mutation grew more efficiently than SV. The P10 virus propagated more rapidly and grew more efficiently than SV and T2808C+A5054G and reached a higher viral load (95.1- and 8.5-fold, respectively) at 20days post-inoculation. An immunofluorescence analysis revealed that a high percentage (>80%) of cells inoculated with the P10 virus expressed ORF2 proteins, while relatively low percentages (nearly 30% or 5%) inoculated with T2808C+A5054G or SV, respectively, expressed ORF2 proteins. We found that not only non-synonymous but also synonymous HEV mutations are independently associated with increased virus production.

Characterization and epitope mapping of monoclonal antibodies raised against rat hepatitis E virus capsid protein: An evaluation of their neutralizing activity in a cell culture system.

Hepatitis E virus (HEV) is the causative agent of acute hepatitis. Rat HEV is a recently discovered virus related to, but distinct from, human HEV. Since laboratory rats can be reproducibly infected with rat HEV and a cell culture system has been established for rat HEV, this virus may be used as a surrogate virus for human HEV, enabling studies on virus replication and mechanism of infection. However, monoclonal antibodies (MAbs) against rat HEV capsid (ORF2) protein are not available. In this study, 12 murine MAbs were generated against a recombinant ORF2 protein of rat HEV (rRatHEV-ORF2: amino acids 101-644) and were classified into at least six distinct groups by epitope mapping and a cross-reactivity analysis with human HEV ORF2 proteins. Two non-cross-reactive MAbs recognizing the protruding (P) domain detected both non-denatured and denatured rRatHEV-ORF2 protein and efficiently captured cell culture-produced rat HEV particles that had been treated with deoxycholate and trypsin, but not those without prior treatment. In addition, these two MAbs were able to efficiently neutralize replication of cell culture-generated rat HEV particles without lipid membranes (but not those with lipid membranes) in a cell culture system, similar to human HEV.

Hepatitis E virus egress depends on the exosomal pathway, with secretory exosomes derived from multivesicular bodies.

Our previous studies indicated that hepatitis E virus (HEV) forms membrane-associated particles in the cytoplasm, most likely by budding into intracellular vesicles, and requires the multivesicular body (MVB) pathway to release virus particles, and the released HEV particles with a lipid membrane retain the trans-Golgi network protein 2 on their surface. To examine whether HEV utilizes the exosomal pathway to release the virus particles, we analysed whether the virion release from PLC/PRF/5 cells infected with genotype 3 HEV (strain JE03-1760F) is affected by treatment with bafilomycin A1 or GW4869, or by the introduction of a small interfering RNA (siRNA) against Rab27A or Hrs. The extracellular HEV RNA titre was increased by treatment with bafilomycin A1, but was decreased by treatment with GW4869. The relative levels of virus particles released from cells depleted of Rab27A or Hrs were decreased to 16.1 and 11.5 %, respectively, of that released from cells transfected with negative control siRNA. Electron microscopic observations revealed the presence of membrane-associated virus-like particles with a diameter of approximately 50 nm within the MVB, which possessed internal vesicles in infected cells. Immunoelectron microscopy showed positive immunogold staining for the HEV ORF2 protein on the intraluminal vesicles within the MVB. Additionally, immunofluorescence analysis indicated the triple co-localization of the ORF2, ORF3 and CD63 proteins in the cytoplasm, as specific loculated signals, supporting the presence of membrane-associated HEV particles within the MVB. These findings indicate that membrane-associated HEV particles are released together with internal vesicles through MVBs by the cellular exosomal pathway.

Rat hepatitis E virus derived from wild rats (Rattus rattus) propagates efficiently in human hepatoma cell lines.

Although rat hepatitis E virus (HEV) has been identified in wild rats, no cell culture systems for this virus have been established. A recent report suggesting the presence of antibodies against rat HEV in human sera encouraged us to cultivate rat HEV in human cells. When liver homogenates obtained from wild rats (Rattus rattus) in Indonesia were inoculated onto human hepatocarcinoma cells, the rat HEV replicated efficiently in PLC/PRF/5, HuH-7 and HepG2 cells, irrespective of its genetic group (G1-G3). The rat HEV particles released from cultured cells harbored lipid-associated membranes on their surface that were depleted by treatment with detergent and protease, with the buoyant density in sucrose shifting from 1.15-1.16 g/ml to 1.27-1.28 g/ml. A Northern blotting analysis revealed genomic RNA of 7.0 kb and subgenomic RNA of 2.0 kb in the infected cells. The subgenomic RNA of G1-G3 each possessed the extreme 5'-end sequence of GUAGC (nt 4933-4937), downstream of the highly conserved sequence of GAAUAACA (nt 4916-4923). The establishment of culture systems for rat HEV would allow for extended studies of the mechanisms of viral replication and functional roles of HEV proteins. Further investigation is required to clarify the zoonotic potential of rat HEV.

Marked genomic heterogeneity of rat hepatitis E virus strains in Indonesia demonstrated on a full-length genome analysis.

Rat hepatitis E virus (HEV) strains have recently been isolated in several areas of Germany, Vietnam, the United States, Indonesia and China. However, genetic information regarding these rat HEV strains is limited. A total of 369 wild rats (Rattus rattus) captured in Central Java (Solo) and on Lombok Island, Indonesia were tested for the presence of rat HEV-specific antibodies and RNA. Overall, 137 rats (37.1%) tested positive for rat anti-HEV antibodies, while 97 (26.3%) had rat HEV RNA detectable on reverse transcription-PCR with primers targeting the ORF1-ORF2 junctional region. The 97 HEV strains recovered from these viremic rats were 76.3-100% identical to each other in an 840-nucleotide sequence and 75.4-88.4% identical to the rat HEV strains reported in Germany and Vietnam. Five representative Indonesian strains, one from each of five phylogenetic clusters, whose entire genomic sequence was determined, were segregated into three genetic groups (a German type, Vietnamese type and novel type), which differed from each other by 19.5-23.5 (22.0 ± 1.7)% over the entire genome. These results suggest the presence of at least three genetic groups of rat HEV and indicate the circulation of polyphyletic strains of rat HEV belonging to three distinct genetic groups in Indonesia.

The membrane on the surface of hepatitis E virus particles is derived from the intracellular membrane and contains trans-Golgi network protein 2.

Our previous studies demonstrated that hepatitis E virus (HEV) requires the multivesicular body (MVB) pathway to release virus particles, suggesting that HEV utilizes the cellular ESCRT machinery in the cytoplasm, not at the cell surface, to be released from infected cells. In this study, we generated a murine monoclonal antibody (mAb) against the membrane-associated HEV particles to examine whether the membrane is derived from intracellular vesicles or the cell surface. An established mAb, TA1708, was found to capture the membrane-associated HEV particles, but not the membrane-dissociated particles or fecal HEV, in an immunocapture RT-PCR assay. Furthermore, digitonin treatment confirmed that the membrane on the surface of cell-culture-generated HEV particles was a lipid membrane. Double immunofluorescence staining revealed that mAb TA1708 specifically recognizes trans-Golgi network protein 2 (TGOLN2), an intracellular antigen derived from the trans-Golgi network. Supporting these findings, HEV particles with lipid membranes and ORF3 proteins on their surface were found abundantly in the lysates of HEV-infected cells. These results indicate that HEV forms membrane-associated particles in the cytoplasm, most likely by budding into intracellular vesicles, and that the released HEV particles with a lipid membrane retain the antigenicity of TGOLN2 on their surface.

Molecular characterization of a novel hepatitis E virus (HEV) strain obtained from a wild boar in Japan that is highly divergent from the previously recognized HEV strains.

Although a consensus classification system for hepatitis E virus (HEV) genotypes is currently unavailable, HEV variants (JBOAR135-Shiz09 and wbJOY_06) from wild boars (Sus scrofa leucomystax) have provisionally been classified into two novel genotypes (5 and 6). While performing a survey of HEV infections among 566 wild boars that were captured in Japan between January 2010 and August 2013, we found 24 boars (4.2%) with ongoing HEV infections: 13 had genotype 3 HEV, 10 had genotype 4 HEV and the remaining boar possessed a novel HEV variant (designated wbJNN_13). The entire wbJNN_13 genome comprised 7247 nucleotides excluding the poly(A) tail, and was highly divergent from known genotype 1 to 4 HEV isolates derived from humans, swine, wild boars, deer, mongoose and rabbits by 22.4-28.2%, JBOAR135-Shiz09 and wbJOY_06 by 19.6-21.9% and rat, ferret, bat and avian HEV isolates by 40.9-46.1% over the entire genome. Phylogenetic trees confirmed that wbJNN_13 is distantly related to all known HEV isolates. A Simplot analysis revealed no significant recombination among the existing HEV strains. These results indicate the presence of at least three genetic lineages of presumably boar-indigenous HEV strains. Further studies to fully understand the extent of the genomic heterogeneity of HEV variants infecting wild boars are warranted.

Frequent detection and characterization of hepatitis E virus variants in wild rats (Rattus rattus) in Indonesia.

One hundred sixteen rats (Rattus rattus) captured in Indonesia from 2011 to 2012 were investigated for the prevalence of hepatitis E virus (HEV)-specific antibodies and HEV RNA. Using an ELISA based on HEV genotype 4 with an ad hoc cutoff value of 0.500, 18.1 % of the rats tested positive for anti-HEV IgG. By nested RT-PCR, 14.7 % of the rats had rat HEV RNA, and none were positive for HEV genotype 1-4. A high HEV prevalence among rats was associated with lower sanitary conditions in areas with a high population density. Sixteen of the 17 HEV isolates obtained from infected rats showed >93.0 % nucleotide sequence identity within the 840-nucleotide ORF1-ORF2 sequence and were most closely related to a Vietnamese strain (85.9-87.9 % identity), while the remaining isolate differed from known rat HEV strains by 18.8-23.3 % and may belong to a novel lineage of rat HEV. These results suggest a wide distribution of rat HEV with divergent genomes.

Molecular analysis of hepatitis E virus from farm rabbits in Inner Mongolia, China and its successful propagation in A549 and PLC/PRF/5 cells.

Rabbit hepatitis E virus (HEV) strains have recently been isolated in several areas of China and in the US and France. However, the host range, distribution and zoonotic potential of these HEV strains remain unknown and their propagation in cultured cells has not yet been reported. A total of 211 4-month-old rabbits raised on a farm in Inner Mongolia were tested for the presence of anti-HEV antibodies and HEV RNA. Overall, 121 rabbits (57.3%) tested positive for anti-HEV antibodies, and 151 (71.6%) had detectable HEV RNA. The 174 HEV strains recovered from these viremic rabbits, including two distinct strains each from 23 rabbits, differed from each other by up to 13.6% in a 412-nucleotide (nt) sequence within ORF2, and were 89.3-95.9% identical to the reported rabbit HEV strains in other provinces of China. Three representative Inner Mongolian strains, one each from three phylogenetic clusters, whose entire genomic sequences were determined, shared 79.6-96.7% identities with reported rabbit HEV strains within the entire or 242- to 1349-nt partial genomic sequence. Rabbit HEV strains recovered from liver tissues of rabbits with a high HEV load propagated efficiently in human cell lines (A549 and PLC/PRF/5 cells), suggesting the potential zoonotic risk of rabbit HEV.

Identification of four novel subgenotypes (C13-C16) and two inter-genotypic recombinants (C12/G and C13/B3) of hepatitis B virus in Papua province, Indonesia.

Four novel subgenotypes (C6, C11, C12, and D6) of hepatitis B virus (HBV) were identified in Papua, a multiethnic province of Indonesia. To characterize the HBV strains in Papua, serum samples collected from 515 indigenous inhabitants (mean age: 26.6±9.6 years) in a previously unexamined area, Nabire, located in northern Papua, were used in the present study. Among 46 samples whose 1.6-kilobase (kb) HBV DNA sequence was amplified, 38 (83%) were typeable into known subgenotypes [B3 (n=4), C1 (n=2), C5, (n=1), C6 (n=5), C12 (n=13), and D6 (n=13)]. An analysis of the full-length sequence of the eight remaining HBV/C isolates whose sequence was either unclassifiable or uncertain within the 1.6-kb sequence showed no significant evidence of recombination in six isolates, and inter-genotypic recombination in two isolates (NAB20 and NAB46). By pairwise comparisons and a maximum-likelihood phylogenetic analysis, six non-recombinant isolates were considered significantly remote from known HBV/C isolates of subgenotypes C1-C12, and were classifiable into four novel subgenotypes (tentatively designated C13-C16). NAB20 and NAB46 were hybrids of C13/B3 and C12/G, respectively, displaying recombination breakpoints in the 5'-terminus of the P gene. Notably, the distribution of presumably indigenous subgenotypes C11-C16 was associated with particular language speakers in Papua.

A549 and PLC/PRF/5 cells can support the efficient propagation of swine and wild boar hepatitis E virus (HEV) strains: demonstration of HEV infectivity of porcine liver sold as food.

Recent evidence has indicated the cross-species transmission of hepatitis E virus (HEV) from pigs and wild boars to humans, causing zoonosis, mostly via consumption of uncooked or undercooked animal meat/viscera. However, no efficient cell culture system for swine and boar HEV strains has been established. We inoculated A549 cells with 12 swine and boar HEV strains of liver, feces, or serum origin at an HEV load of ≥2.0 × 10(4) copies per well and found that the HEV progeny replicated as efficiently as human HEV strains, with a maximum load of ~10(8) copies/ml. However, the HEV load in the culture medium at 30 days post-inoculation differed markedly by inoculum, ranging from 1.0 × 10(2) to 1.1 × 10(7) copies/ml upon inoculation at a lower load of approximately 10(5) copies per well. All progeny were passaged successfully onto A549 and PLC/PRF/5 cells. In sharp contrast, no progeny viruses were detectable in the culture supernatant upon inoculation with 13 swine and boar HEV strains at an HEV load of <1.8 × 10(4) copies per well. The present study also demonstrates that swine liver sold as food can be infectious, supporting the risk of zoonotic food-borne HEV infection.