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Nagata S, Kiyohara R, Toh H. Constraint of Base Pairing on HDV Genome Evolution. Viruses 2021; 13:v13122350. [PMID: 34960619 PMCID: PMC8708965 DOI: 10.3390/v13122350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 10/11/2021] [Accepted: 11/02/2021] [Indexed: 11/17/2022] Open
Abstract
The hepatitis delta virus is a single-stranded circular RNA virus, which is characterized by high self-complementarity. About 70% of the genome sequences can form base-pairs with internal nucleotides. There are many studies on the evolution of the hepatitis delta virus. However, the secondary structure has not been taken into account in these studies. In this study, we developed a method to examine the effect of base pairing as a constraint on the nucleotide substitutions during the evolution of the hepatitis delta virus. The method revealed that the base pairing can reduce the evolutionary rate in the non-coding region of the virus. In addition, it is suggested that the non-coding nucleotides without base pairing may be under some constraint, and that the intensity of the constraint is weaker than that by the base pairing but stronger than that on the synonymous site.
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Abstract
HDV is a small, defective RNA virus that requires the HBsAg of HBV for its assembly, release, and transmission. Chronic HBV/HDV infection often has a severe clinical outcome and is difficult to treat. The important role of a robust virus-specific T cell response for natural viral control has been established for many other chronic viral infections, but the exact role of the T cell response in the control and progression of chronic HDV infection is far less clear. Several recent studies have characterised HDV-specific CD4+ and CD8+ T cell responses on a peptide level. This review comprehensively summarises all HDV-specific T cell epitopes described to date and describes our current knowledge of the role of T cells in HDV infection. While we now have better tools to study the adaptive anti-HDV-specific T cell response, further efforts are needed to define the HLA restriction of additional HDV-specific T cell epitopes, establish additional HDV-specific MHC tetramers, understand the degree of cross HDV genotype reactivity of individual epitopes and understand the correlation of the HBV- and HDV-specific T cell response, as well as the breadth and specificity of the intrahepatic HDV-specific T cell response.
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Key Words
- ADAR1, adenosine deaminases acting on RNA
- ALT, alanine aminotransferase
- AST, aspartate aminotransferase
- CD4+
- CD8+
- ELISpot, enzyme-linked immune spot assay
- HBV
- HDAg, hepatitis delta antigen
- HDV
- Hepatitis Delta
- ICS, intracellular cytokine staining
- IFN-, interferon-
- L-HDAg, large hepatitis delta antigen
- MAIT, mucosa-associated invariant T cells
- NK cells, natural killer cells
- NTCP, sodium taurocholate co-transporting polypeptide
- PBMCs, peripheral blood mononuclear cells
- PD-1, programmed cell death protein 1
- PTM, post-translational modification
- Peg-IFN-α, pegylated interferon alpha
- S-HDAg, small hepatitis delta antigen
- T cell
- TCF, T cell-specific transcription factor
- TNFα, tumour necrosis factor-α
- Th1, T helper 1
- aa, amino acid(s)
- cccDNA, covalently closed circular DNA
- epitope
- viral escape
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3
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Bergner LM, Orton RJ, Broos A, Tello C, Becker DJ, Carrera JE, Patel AH, Biek R, Streicker DG. Diversification of mammalian deltaviruses by host shifting. Proc Natl Acad Sci U S A 2021; 118:e2019907118. [PMID: 33397804 PMCID: PMC7826387 DOI: 10.1073/pnas.2019907118] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Hepatitis delta virus (HDV) is an unusual RNA agent that replicates using host machinery but exploits hepatitis B virus (HBV) to mobilize its spread within and between hosts. In doing so, HDV enhances the virulence of HBV. How this seemingly improbable hyperparasitic lifestyle emerged is unknown, but it underpins the likelihood that HDV and related deltaviruses may alter other host-virus interactions. Here, we show that deltaviruses diversify by transmitting between mammalian species. Among 96,695 RNA sequence datasets, deltaviruses infected bats, rodents, and an artiodactyl from the Americas but were absent from geographically overrepresented Old World representatives of each mammalian order, suggesting a relatively recent diversification within the Americas. Consistent with diversification by host shifting, both bat and rodent-infecting deltaviruses were paraphyletic, and coevolutionary modeling rejected cospeciation with mammalian hosts. In addition, a 2-y field study showed common vampire bats in Peru were infected by two divergent deltaviruses, indicating multiple introductions to a single host species. One vampire bat-associated deltavirus was detected in the saliva of up to 35% of individuals, formed phylogeographically compartmentalized clades, and infected a sympatric bat, illustrating horizontal transmission within and between species on ecological timescales. Consistent absence of HBV-like viruses in two deltavirus-infected bat species indicated acquisitions of novel viral associations during the divergence of bat and human-infecting deltaviruses. Our analyses support an American zoonotic origin of HDV and reveal prospects for future cross-species emergence of deltaviruses. Given their peculiar life history, deltavirus host shifts will have different constraints and disease outcomes compared to ordinary animal pathogens.
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Affiliation(s)
- Laura M Bergner
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland;
- Medical Research Center-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, Scotland
| | - Richard J Orton
- Medical Research Center-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, Scotland
| | - Alice Broos
- Medical Research Center-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, Scotland
| | - Carlos Tello
- Association for the Conservation and Development of Natural Resources, 15037 Lima, Perú
- Yunkawasi, 15049 Lima, Perú
| | - Daniel J Becker
- Department of Biology, University of Oklahoma, Norman, OK 73019
| | - Jorge E Carrera
- Departamento de Mastozoología, Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima 15081, Perú
- Programa de Conservación de Murciélagos de Perú, Piura 20001, Perú
| | - Arvind H Patel
- Medical Research Center-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, Scotland
| | - Roman Biek
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland
| | - Daniel G Streicker
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland;
- Medical Research Center-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, Scotland
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Iwamoto M, Shibata Y, Kawasaki J, Kojima S, Li YT, Iwami S, Muramatsu M, Wu HL, Wada K, Tomonaga K, Watashi K, Horie M. Identification of novel avian and mammalian deltaviruses provides new insights into deltavirus evolution. Virus Evol 2021; 7:veab003. [PMID: 33614159 PMCID: PMC7882216 DOI: 10.1093/ve/veab003] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Hepatitis delta virus (HDV) is a satellite virus that requires hepadnavirus envelope proteins for its transmission. Although recent studies identified HDV-related deltaviruses in certain animals, the evolution of deltaviruses, such as the origin of HDV and the mechanism of its coevolution with its helper viruses, is unknown, mainly because of the phylogenetic gaps among deltaviruses. Here, we identified novel deltaviruses of passerine birds, woodchucks, and white-tailed deer by extensive database searches and molecular surveillance. Phylogenetic and molecular epidemiological analyses suggest that HDV originated from mammalian deltaviruses and the past interspecies transmission of mammalian and passerine deltaviruses. Further, metaviromic and experimental analyses suggest that the satellite-helper relationship between HDV and hepadnavirus was established after the divergence of the HDV lineage from non-HDV mammalian deltaviruses. Our findings enhance our understanding of deltavirus evolution, diversity, and transmission, indicating the importance of further surveillance for deltaviruses.
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Affiliation(s)
- Masashi Iwamoto
- Department of Virology II, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan
- Mathematical Biology Laboratory, Department of Biology, Faculty of Sciences, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yukino Shibata
- Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0810, Japan
| | - Junna Kawasaki
- Institute for Frontier Life and Medical Sciences, Kyoto University, 53 Kawahara-cho, Shogo-in, Sakyo, Kyoto 606-8507, Japan
- Department of Mammalian Regulatory Network, Graduate School of Biostudies, Kyoto University, 53 Kawahara-cho, Shogo-in, Sakyo, Kyoto 606-8507, Japan
| | - Shohei Kojima
- Institute for Frontier Life and Medical Sciences, Kyoto University, 53 Kawahara-cho, Shogo-in, Sakyo, Kyoto 606-8507, Japan
- Genome Immunobiology RIKEN Hakubi Research Team, RIKEN Center for Integrative Medical Sciences and RIKEN Cluster for Pioneering Research, 1-7-22, Suehiro-Cho, Tsurumi-Ward, Yokohama 230-0045, Japan
| | - Yung-Tsung Li
- Hepatitis Research Center, National Taiwan University Hospital, 7 Chung Shan South Road, Taipei 10002, Taiwan
| | - Shingo Iwami
- Mathematical Biology Laboratory, Department of Biology, Faculty of Sciences, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Masamichi Muramatsu
- Department of Virology II, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan
| | - Hui-Lin Wu
- Hepatitis Research Center, National Taiwan University Hospital, 7 Chung Shan South Road, Taipei 10002, Taiwan
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, 7 Chung Shan South Road, Taipei 10002, Taiwan
| | - Kazuhiro Wada
- Faculty of Science, Hokkaido University, Kita-10 Nishi-8, Kita-ku, Sapporo 060-0810, Japan
| | - Keizo Tomonaga
- Institute for Frontier Life and Medical Sciences, Kyoto University, 53 Kawahara-cho, Shogo-in, Sakyo, Kyoto 606-8507, Japan
- Department of Mammalian Regulatory Network, Graduate School of Biostudies, Kyoto University, 53 Kawahara-cho, Shogo-in, Sakyo, Kyoto 606-8507, Japan
- Department of Molecular Virology, Graduate School of Medicine, Kyoto University, 53 Kawahara-cho, Shogo-in, Sakyo, Kyoto 606-8507, Japan
| | - Koichi Watashi
- Department of Virology II, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan
- Department of Applied Biological Sciences, Tokyo University of Science, 2641 Yamazaki, Noda 278-8510, Japan
| | - Masayuki Horie
- Institute for Frontier Life and Medical Sciences, Kyoto University, 53 Kawahara-cho, Shogo-in, Sakyo, Kyoto 606-8507, Japan
- Hakubi Center for Advanced Research, Kyoto University, 53 Kawahara-cho, Shogo-in, Sakyo, Kyoto 606-8507, Japan
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5
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Coller KE, Butler EK, Luk KC, Rodgers MA, Cassidy M, Gersch J, McNamara AL, Kuhns MC, Dawson GJ, Kaptue L, Bremer B, Wedemeyer H, Cloherty GA. Development and performance of prototype serologic and molecular tests for hepatitis delta infection. Sci Rep 2018; 8:2095. [PMID: 29391553 PMCID: PMC5794785 DOI: 10.1038/s41598-018-20455-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 01/18/2018] [Indexed: 12/18/2022] Open
Abstract
Worldwide, an estimated 5% of hepatitis B virus (HBV) infected people are coinfected with hepatitis delta virus (HDV). HDV infection leads to increased mortality over HBV mono-infection, yet HDV diagnostics are not widely available. Prototype molecular (RNA) and serologic (IgG) assays were developed for high-throughput testing on the Abbott m2000 and ARCHITECT systems, respectively. RNA detection was achieved through amplification of a ribozyme region target, with a limit of detection of 5 IU/ml. The prototype serology assay (IgG) was developed using peptides derived from HDV large antigen (HDAg), and linear epitopes were further identified by peptide scan. Specificity of an HBV negative population was 100% for both assays. A panel of 145 HBsAg positive samples from Cameroon with unknown HDV status was tested using both assays: 16 (11.0%) had detectable HDV RNA, and 23 (15.7%) were sero-positive including the 16 HDV RNA positive samples. Additionally, an archival serial bleed panel from an HDV superinfected chimpanzee was tested with both prototypes; data was consistent with historic testing data using a commercial total anti-Delta test. Overall, the two prototype assays provide sensitive and specific methods for HDV detection using high throughput automated platforms, allowing opportunity for improved diagnosis of HDV infected patients.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Birgit Bremer
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Heiner Wedemeyer
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
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Shirvani-Dastgerdi E, Amini-Bavil-Olyaee S, Alavian SM, Trautwein C, Tacke F. Comprehensive analysis of mutations in the hepatitis delta virus genome based on full-length sequencing in a nationwide cohort study and evolutionary pattern during disease progression. Clin Microbiol Infect 2014; 21:510.e11-23. [PMID: 25656625 DOI: 10.1016/j.cmi.2014.12.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 11/21/2014] [Accepted: 12/18/2014] [Indexed: 02/06/2023]
Abstract
Delta hepatitis, caused by co-infection or super-infection of hepatitis D virus (HDV) in hepatitis B virus (HBV) -infected patients, is the most severe form of chronic hepatitis, often progressing to liver cirrhosis and liver failure. Although 15 million individuals are affected worldwide, molecular data on the HDV genome and its proteins, small and large delta antigen (S-/L-HDAg), are limited. We therefore conducted a nationwide study in HBV-HDV-infected patients from Iran and successfully amplified 38 HDV full genomes and 44 L-HDAg sequences from 34 individuals. Phylogenetic analyses of full-length HDV and L-HDAg isolates revealed that all strains clustered with genotype 1 and showed high genotypic distances to HDV genotypes 2 to 8, with a maximal distance to genotype 3. Longitudinal analyses in individual patients indicated a reverse evolutionary trend, especially in L-HDAg amino acid composition, over time. Besides multiple sequence variations in the hypervariable region of HDV, nucleotide substitutions preferentially occurred in the stabilizing P4 domain of the HDV ribozyme. A high rate of single amino acid changes was detected in structural parts of L-HDAg, whereas its post-translational modification sites were highly conserved. Interestingly, several non-synonymous mutations were positively selected that affected immunogenic epitopes of L-HDAg towards CD8 T-cell- and B-cell-driven immune responses. Hence, our comprehensive molecular analysis comprising a nationwide cohort revealed phylogenetic relationships and provided insight into viral evolution within individual hosts. Moreover, preferential areas of frequent mutations in the HDV ribozyme and antigen protein were determined in this study.
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Affiliation(s)
| | - S Amini-Bavil-Olyaee
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Harlyne J. Norris Cancer Research Tower, Los Angeles, CA, USA
| | - S Moayed Alavian
- Baqiyatallah Research Centre for Gastroenterology and Liver Diseases, Baqiyatallah University of Medical Sciences, Tehran, Iran.
| | - C Trautwein
- Department of Medicine III, RWTH-University Hospital Aachen, Aachen, Germany
| | - F Tacke
- Department of Medicine III, RWTH-University Hospital Aachen, Aachen, Germany
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7
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Lin CC, Yang ZW, Iang SB, Chao M. Reduced genetic distance and high replication levels increase the RNA recombination rate of hepatitis delta virus. Virus Res 2014; 195:79-85. [PMID: 25172581 DOI: 10.1016/j.virusres.2014.08.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 08/13/2014] [Accepted: 08/19/2014] [Indexed: 12/25/2022]
Abstract
Hepatitis delta virus (HDV) replication is carried out by host RNA polymerases. Since homologous inter-genotypic RNA recombination is known to occur in HDV, possibly via a replication-dependent process, we hypothesized that the degree of sequence homology and the replication level should be related to the recombination frequency in cells co-expressing two HDV sequences. To confirm this, we separately co-transfected cells with three different pairs of HDV genomic RNAs and analyzed the obtained recombinants by RT-PCR followed by restriction fragment length polymorphism and sequencing analyses. The sequence divergence between the clones ranged from 24% to less than 0.1%, and the difference in replication levels was as high as 100-fold. As expected, significant differences were observed in the recombination frequencies, which ranged from 0.5% to 47.5%. Furthermore, varying the relative amounts of parental RNA altered the dominant recombinant species produced, suggesting that template switching occurs frequently during the synthesis of genomic HDV RNA. Taken together, these data suggest that during the host RNA polymerase-driven RNA recombination of HDV, both inter- and intra-genotypic recombination events are important in shaping the genetic diversity of HDV.
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Affiliation(s)
- Chia-Chi Lin
- Division of Mcrobiology, Graduate Institue of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-yang 333, Taiwan.
| | - Zhi-Wei Yang
- Division of Mcrobiology, Graduate Institue of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-yang 333, Taiwan.
| | - Shan-Bei Iang
- Division of Mcrobiology, Graduate Institue of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-yang 333, Taiwan.
| | - Mei Chao
- Division of Mcrobiology, Graduate Institue of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-yang 333, Taiwan; Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Tao-yang 333, Taiwan.
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8
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Alvarado-Mora MV, Locarnini S, Rizzetto M, Pinho JRR. An update on HDV: virology, pathogenesis and treatment. Antivir Ther 2013; 18:541-8. [PMID: 23792471 DOI: 10.3851/imp2598] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/29/2012] [Indexed: 02/06/2023]
Abstract
Hepatitis delta is an inflammatory liver disease caused by infection with HDV. HDV is a single-stranded circular RNA pathogen with a diameter of 36 nm. HDV is classified in the genus Deltavirus and is still awaiting a final taxonomic classification up to the family level. HDV shares similarities with satellite RNA and viroids including a small circular single-stranded RNA with secondary structure that replicates through the 'double rolling circle' mechanism. The HDV RNA genome is capable of self-cleavage through a ribozyme and encodes only one structural protein, the hepatitis delta antigen (HDAg), from the antigenomic RNA. There are two forms of HDAg, a shorter (S; 22 kDa) and a longer (L; 24 kDa) form, the latter generated from an RNA editing mechanism. The S form is essential for viral genomic replication. The L form participates in the assembly and formation of HDV. For complete replication and transmission, HDV requires the hepatitis B surface antigen (HBsAg). Thus, HDV infection only occurs in HBsAg-positive individuals, either as acute coinfection in treatment-naive HBV-infected persons, or as superinfection in patients with pre-existing chronic hepatitis B (CHB). HDV is found throughout the world, but its prevalence, incidence, clinical features and epidemiological characteristics vary by geographic region. There are eight genotypes (1 to 8) distributed over different geographic areas: HDV-1 is distributed worldwide, whereas HDV-2 to 8 are seen more regionally. Levels of HDV viraemia change over the course of HDV infection, being significantly higher in patients with early chronic hepatitis than in cirrhosis. Chronic HDV infection leads to more severe liver disease than chronic HBV monoinfection with an accelerated course of fibrosis progression, an increased risk of hepatocellular carcinoma and early decompensation in the setting of established cirrhosis. Current treatments include pegylated interferon-α and liver transplantation; the latter of which can be curative. Further studies are needed to develop better treatment strategies for this challenging disease.
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Affiliation(s)
- Mónica V Alvarado-Mora
- Laboratory of Tropical Gastroenterology and Hepatology 'João Alves de Queiroz and Castorina Bittencourt Alves', Institute of Tropical Medicine, Department of Gastroenterology, University of São Paulo School of Medicine, São Paulo, Brazil.
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9
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Liao FT, Hsu LS, Ko JL, Lin CC, Sheu GT. Multiple genomic sequences of hepatitis delta virus are associated with cDNA promoter activity and RNA double rolling-circle replication. J Gen Virol 2012; 93:577-587. [DOI: 10.1099/vir.0.037507-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To understand how DNA-dependent RNA polymerase II (pol II) recognizes hepatitis delta virus (HDV) RNA as a template, it is first necessary to identify the HDV sequence that acts as a promoter of pol II-initiated RNA synthesis. Therefore, we isolated the pol II-response element from HDV cDNA and examined the regulation by hepatitis delta antigens (HDAgs). Two HDV cDNA fragments containing bidirectional promoter activity were identified. One was located at nt 1582–1683 (transcription-promoter region 1, TR-P1) and the other at nt 1223–1363 (transcription-internal region 5, TR-I5). The promoter activities of these two regions were enhanced by HDAgs to differing degrees. Next, the role of these sequences in an HDV cDNA-free RNA replication system was characterized by site-directed mutagenesis. Our data showed that: (i) the AUG codon at the HDAg ORF of HDV RNA (nt 1599–1601) that mutates to UAG (amber stop codon) results in loss of dimeric but not monomeric HDV RNA synthesis. (ii) A 5 nt mutation of TR-P1 (P1-m5, nt 1670–1674) abolishes RNA replication completely. Two-nucleotide-mutated RNA (P1-m2, nt 1662–1663) is able to synthesize short RNAs but not monomeric HDV RNA. (iii) A mutation in 5 nt at the TR-I5 region (I5-m5, nt 1351–1355) also abolishes HDV replication. Mutants with 2 nt mutations (I5-m2, nt 1351–1352) or 3 nt mutations (I5-m3, nt 1353–1355) inhibit HDV dimeric but not monomeric RNA synthesis. Furthermore, large HDAg is expressed in cells transfected with I5-m3 and I5-m2 RNAs and that demonstrate the RNA-editing event in the monomeric HDV RNA. These results provide further understanding of the double rolling-circle mechanism in HDV RNA replication.
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Affiliation(s)
- Fu-Tien Liao
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan, ROC
| | - Li-Sung Hsu
- Institute of Biochemistry and Biotechnology, Chung Shan Medical University, Taichung, Taiwan, ROC
| | - Jiunn-Liang Ko
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan, ROC
| | - Chun-Che Lin
- Department of Internal Medicine, Chung Shan Medical University Hospital, Taichung, Taiwan, ROC
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan, ROC
| | - Gwo-Tarng Sheu
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan, ROC
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10
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Abstract
Hepatitis delta virus (HDV) is a small, defective RNA virus that can infect only individuals who have hepatitis B virus (HBV); worldwide more than 15 million people are co-infected. There are eight reported genotypes of HDV with unexplained variations in their geographical distribution and pathogenicity. The hepatitis D virion is composed of a coat of HBV envelope proteins surrounding the nucleocapsid, which consists of a single-stranded, circular RNA genome complexed with delta antigen, the viral protein. HDV is clinically important because although it suppresses HBV replication, it causes severe liver disease with rapid progression to cirrhosis and hepatic decompensation. The range of clinical presentation is wide, varying from mild disease to fulminant liver failure. The prevalence of HDV is declining in some endemic areas but increasing in northern and central Europe because of immigration. Treatment of HDV is with pegylated interferon alfa; however, response rates are poor. Increased understanding of the molecular virology of HDV will identify novel therapeutic targets for this most severe form of chronic viral hepatitis.
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Affiliation(s)
- Sarah A Hughes
- Institute of Liver Studies, King's College Hospital, London, UK
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11
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Wang SY, Wu JC, Chiang TY, Huang YH, Su CW, Sheen IJ. Positive selection of hepatitis delta antigen in chronic hepatitis D patients. J Virol 2007; 81:4438-44. [PMID: 17301143 PMCID: PMC1900184 DOI: 10.1128/jvi.02847-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Liver disease may become ameliorated in some patients with chronic hepatitis D virus (HDV) infection. We present here a study based on longitudinal sampling to investigate the viral dynamics in chronic HDV infection. We examined the HDV variants from different time points, especially those before and after the elevation of serum aminotransferase levels. The datasets from each patient were tested for positive selection by using maximum-likelihood methods with heterogeneous selective pressures along the nucleotide sequence. An average of 4.9%, ranging from 3.1 to 6.8%, of the entire delta antigen sites was regulated by a diversifying selection. Most of the positively selected sites were associated with immunogenic domains. Likelihood ratio tests revealed a significant fitness of positive selection over neutrality of the hepatitis delta antigen gene in all patients. We further adapted a neural network method to predict potential cytotoxic T ligand epitopes. Among the HLA-A*0201 cytotoxic T ligand epitopes, three consistent epitopes across all three genotypes were identified: amino acids (aa) 43 to 51, 50 to 58, and 114 to 122. Three patients (60%) had sites evolving under positive selection in the epitope from aa 43 to 51, and four patients (80%) had sites evolving under positive selection in the epitope from aa 114 to 122. The discovery of immunogenic epitopes, especially cytotoxic-T-lymphocyte ligands, associated with chronic HDV infection may be crucial for further development of novel treatments or designs in vaccine for HDV superinfection.
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Affiliation(s)
- Shen-Yung Wang
- Department of Medical Research and Education, Taipei Veterans General Hospital, 201 Shih-Pai Road, Sec. 2, Taipei 11217, Taiwan
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12
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Zhou T, Gu W, Ma J, Sun X, Lu Z. Analysis of synonymous codon usage in H5N1 virus and other influenza A viruses. Biosystems 2005; 81:77-86. [PMID: 15917130 DOI: 10.1016/j.biosystems.2005.03.002] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2004] [Revised: 03/05/2005] [Accepted: 03/07/2005] [Indexed: 10/25/2022]
Abstract
In this study, we calculated the codon usage bias in H5N1 virus and performed a comparative analysis of synonymous codon usage patterns in H5N1 virus, five other evolutionary related influenza A viruses and a influenza B virus. Codon usage bias in H5N1 genome is a little slight, which is mainly determined by the base compositions on the third codon position. By comparing synonymous codon usage patterns in different viruses, we observed that the codon usage pattern of H5N1 virus is similar with other influenza A viruses, but not influenza B virus, and the synonymous codon usage in influenza A virus genes is phylogenetically conservative, but not strain-specific. Synonymous codon usage in genes encoded by different influenza A viruses is genus conservative. Compositional constraints could explain most of the variation of synonymous codon usage among these virus genes, while gene function is also correlated to synonymous codon usages to a certain extent. However, translational selection and gene length have no effect on the variations of synonymous codon usage in these virus genes.
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Affiliation(s)
- Tong Zhou
- Key Laboratory of Molecular and Biomolecular Electronics of the Ministry of Education, Southeast University, Nanjing, Jiangsu 210096, China
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13
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Anisimova M, Yang Z. Molecular evolution of the hepatitis delta virus antigen gene: recombination or positive selection? J Mol Evol 2005; 59:815-26. [PMID: 15599513 DOI: 10.1007/s00239-004-0112-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Accepted: 06/29/2004] [Indexed: 02/08/2023]
Abstract
We present the statistical analysis of diversifying selective pressures on the hepatitis D antigen gene (HDAg). Thirty-three distinct HDAg sequences from subtypes I, II, and III were tested for positive selection using maximum likelihood methods based on models of codon substitution that allow variable selective pressures across sites. Such methods have been shown to be sufficiently accurate and successful in detecting positive selection in a variety of viral and nonviral protein-coding genes. About 11% of codon sites in HDAg were estimated to be under diversifying selection. Remarkably, most of the residues predicted to evolve under positive selection were located in the immunogenic domain and the N-terminus region with reported antigenic activity. These sites are potential targets of the host's immune response. Identification of residues mutating to escape immune recognition may help to distinguish the most virulent strains and aid vaccine design. Possible interplay between positive selection and recombination on the gene is discussed but no significant evidence for recombination was found.
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Affiliation(s)
- Maria Anisimova
- Department of Biology, University College London, London WC1E 6BT, UK.
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Robertson HD, Neel OD. Virus Origins. ORIGIN AND EVOLUTION OF VIRUSES 1999. [PMCID: PMC7155586 DOI: 10.1016/b978-012220360-2/50003-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 10/29/2022]
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15
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Escalante AA, Lal AA, Ayala FJ. Genetic polymorphism and natural selection in the malaria parasite Plasmodium falciparum. Genetics 1998; 149:189-202. [PMID: 9584096 PMCID: PMC1460124 DOI: 10.1093/genetics/149.1.189] [Citation(s) in RCA: 186] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We have studied the genetic polymorphism at 10 Plasmodium falciparum loci that are considered potential targets for specific antimalarial vaccines. The polymorphism is unevenly distributed among the loci; loci encoding proteins expressed on the surface of the sporozoite or the merozoite (AMA-1, CSP, LSA-1, MSP-1, MSP-2, and MSP-3) are more polymorphic than those expressed during the sexual stages or inside the parasite (EBA-175, Pfs25, PF48/45, and RAP-1). Comparison of synonymous and nonsynonymous substitutions indicates that natural selection may account for the polymorphism observed at seven of the 10 loci studied. This inference depends on the assumption that synonymous substitutions are neutral, which we test by analyzing codon bias and G+C content in a set of 92 gene loci. We find evidence for an overall trend towards increasing A+T richness, but no evidence for mutation bias. Although the neutrality of synonymous substitutions is not definitely established, this trend towards an A+T rich genome cannot explain the accumulation of substitutions at least in the case of four genes (AMA-1, CSP, LSA-1, and PF48/45) because the Gleft and right arrow C transversions are more frequent than expected. Moreover, the Tajima test manifests positive natural selection for the MSP-1 and, less strongly, MSP-3 polymorphisms; the McDonald-Kreitman test manifests natural selection at LSA-1 and PF48/45. We conclude that there is definite evidence for positive natural selection in the genes encoding AMA-1, CSP, LSA-1, MSP-1, and Pfs48/45. For four other loci, EBA-175, MSP-2, MSP-3, and RAP-1, the evidence is limited. No evidence for natural selection is found for Pfs25.
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Affiliation(s)
- A A Escalante
- Division of Parasitic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, US Public Health Service, Chamblee, Georgia 30341, USA
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16
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Suzuki Y, Gojobori T. The origin and evolution of human T-cell lymphotropic virus types I and II. Virus Genes 1998; 16:69-84. [PMID: 9562892 DOI: 10.1023/a:1007953826869] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Studies on human T-cell lymphotropic virus types I (HTLV-I) and II (HTLV-II) are briefly reviewed from the viewpoint of molecular evolution, with special reference to the evolutionary rate and evolutionary relationships among these viruses. In particular, it appears that, in contrast to the low level of variability of HTLV-I among different isolates, individual isolates form quasispecies structures. Elucidating the mechanisms connecting these two phenomena will be one of the future problems in the study of the molecular evolution of HTLV-I and HTLV-II.
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Affiliation(s)
- Y Suzuki
- Center for Information Biology, National Institute of Genetics, Mishima, Japan
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17
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Ina Y. Pattern of synonymous and nonsynonymous substitutions: An indicator of mechanisms of molecular evolution. J Genet 1996. [DOI: 10.1007/bf02931754] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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