The Experts below are selected from a list of 3714 Experts worldwide ranked by ideXlab platform
Michinori Kohara - One of the best experts on this subject based on the ideXlab platform.
-
Avian H5N1 influenza virus infection causes severe pneumonia in the Northern tree shrew (Tupaia belangeri).
Virology, 2019Co-Authors: Takahiro Sanada, Mohammad Enamul Hoque Kayesh, Kyoko Tsukiyama-kohara, Fumihiko Yasui, Tomoko Honda, Jun-ichiro Takano, Yumiko Shiogama, Yasuhiro Yasutomi, Michinori KoharaAbstract:Avian-origin influenza viruses like H5N1 and H7N9 often cause severe symptoms with high mortality in humans. Animal models are useful for clarification of the mechanisms of pathogenicity of these infections. In this study, to expand the potential utility of the Northern tree shrew (Tupaia belangeri) for influenza virus infection, we assessed the pathogenicity of H5N1 and H7N9 avian influenza viruses in Tupaia. Infectious virus was detected continuously from nasal, oral, tracheal, and conjunctival swab samples in the animals infected with these viruses. H5N1 influenza virus infection of Tupaia caused severe diffuse pneumonia with fever and weight loss. In contrast, H7N9 influenza virus infection caused focal pneumonia. The severity of pneumonia was correlated with proinflammatory cytokine transcript levels. These results indicated that Tupaia can be another suitable animal model for avian influenza virus research.
-
Susceptibility and initial immune response of Tupaia belangeri cells to dengue virus infection.
Infection genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases, 2017Co-Authors: Mohammad Enamul Hoque Kayesh, Takahiro Sanada, Bouchra Kitab, Michinori Kohara, Daisuke Hayasaka, Kouichi Morita, Kyoko Tsukiyama-koharaAbstract:Abstract Dengue is an emerging disease of great public health significance worldwide. The lack of a suitable infection model has hampered dengue virus (DENV) pathogenesis study, and developing a suitable small animal model has been a long-standing challenge. The aim of this study was to develop a feasible experimental model of DENV infection using Tupaia belangeri . The susceptibility of Tupaia to DENV infection and characteristics of its innate immune response were examined in vitro . We found that Tupaia fibroblast cells support replication of DENV serotypes 1–4 with a linear increase in viral load 24–96 h post-infection in both cells and culture supernatants. DENV-2 resulted in the highest viral growth among all serotypes. To characterize the innate immune response in Tupaia cells during the early phase of DENV infection, we first evaluated the evolutionary relationship between Tupaia Toll-like receptors (TLR1–9) and those of other mammalian species. Phylogenetic analysis showed that Tupaia TLRs are evolutionarily much closer to human than they are to rodent. We next established an innate immune response measurement system by assessing the mRNA expression of TLR1–9 and four cytokines in DENV-infected Tupaia cells. All serotypes induced the upregulation of TLR8 mRNA expression in infected Tupaia cells. Silencing of TLR8 led to an increase in viral replication, indicating the existence of antiviral response through TLR8 on DENV infection. Although upregulation of IFN-β and IL-6 expression was only observed in DENV-1 infected cells and a significant suppression of TNF-α was observed in DENV-2 infected cells alone, IL-8 was upregulated in all DENV-1–4. Thus, this study demonstrates for the first time the susceptibility of Tupaia cells to DENV infections and the role of TLR8 in the anti-viral response of Tupaia cells to DENV. These findings demonstrate the potential utility of Tupaia as a model for DENV research in the future.
-
—Review— Tupaia Belangeri as an Experimental Animal Model for Viral Infection
2016Co-Authors: Kyoko Tsukiyama-kohara, Michinori KoharaAbstract:Abstract: Tupaias, or tree shrews, are small mammals that are similar in appearance to squirrels. The morphological and behavioral characteristics of the group have been extensively characterized, and despite previously being classified as primates, recent studies have placed the group in its own family, the Tupaiidae. Genomic analysis has revealed that the genus Tupaia is closer to humans than it is to rodents. In addition, Tupaias are susceptible to hepatitis B virus and hepatitis C virus. The only other experimental animal that has been demonstrated to be sensitive to both of these viruses is the chimpanzee, but restrictions on animal testing have meant that experiments using chimpanzees have become almost impossible. Consequently, the development of the Tupaia for use as an animal infection model could become a powerful tool for hepatitis virus research and in preclinical studies on drug development
-
Establishment of an intermittent cold stress model using Tupaia belangeri and evaluation of compound C737 targeting neuron-restrictive silencer factor.
Experimental animals, 2016Co-Authors: Chi Hai-ying, Mohammad Enamul Hoque Kayesh, Sayeh Ezzikouri, Bouchra Kitab, Khadija Rebbani, Kiori Nagano, Chiho Yamaguchi, Hirohumi Nakano, Hiroyuki Kouji, Michinori KoharaAbstract:Previous studies have shown that intermittent cold stress (ICS) induces depression-like behaviors in mammals. Tupaia belangeri (the tree shrew) is the only experimental animal other than the chimpanzee that has been shown to be susceptible to infection by hepatitis B and C viruses. Moreover, full genome sequence analysis has revealed strong homology between host proteins in Tupaia and in humans and other primates. Tupaia neuromodulator receptor proteins are also known to have a high degree of homology with their corresponding primate proteins. Based on these similarities, we hypothesized that induction of ICS in Tupaia would provide a useful animal model of stress responses. We exposed young adult Tupaia to ICS and observed decreases in body temperature and body weight in both female and male Tupaia, suggesting that Tupaia are an appropriate animal model for ICS studies. We further examined the efficacy of a new small-molecule compound, C737, against the effects of ICS. C737 mimics the helical structure of neuron-restrictive silencer factor (NRSF/REST), which regulates a wide range of target genes involved in neuronal function and pain modulation. Treatment with C737 significantly reduced stress-induced weight loss in female Tupaia; these effects were stronger than those elicited by the antidepressant agomelatine. These results suggest that Tupaia represents a useful non-rodent ICS model. Our data also provide new insights into the function of NRSF/REST in stress-induced depression and other disorders with epigenetic influences or those with high prevalence in women.
-
property of hepatitis b virus replication in Tupaia belangeri hepatocytes
Biochemical and Biophysical Research Communications, 2016Co-Authors: Takahiro Sanada, Sayeh Ezzikouri, Naoki Yamamoto, Soumaya Benjelloun, Shuko Murakami, Yasuhito Tanaka, Chise Tateno, Kyoko Tsukiyamakohara, Michinori KoharaAbstract:The northern treeshrew (Tupaia belangeri) has been reported to be an effective candidate for animal infection model with hepatitis B virus (HBV). The objective of our study was to analyze the growth characteristics of HBV in Tupaia hepatocytes and the host response to HBV infection. We established primary Tupaia hepatocytes (3–6-week old Tupaia) and infected them with HBV genotypes A, B and C, and all the genotypes proliferated as well as those in human primary hepatocytes (>105 copies/ml in culture supernatant). We next generated a chimeric mouse with Tupaia liver by transplantation of Tupaia primary hepatocytes to urokinase-type plasminogen activator cDNA (cDNA-uPA)/severe combined immunodeficient (SCID) mice and the replacement ratio with Tupaia hepatocytes was found to be more than 95%. Infection of chimeric mice with HBV (genotypes B, C, and D) resulted in HBV-DNA level of 104-106 copies/ml after 8 weeks of infection, which were almost similar to that in humanized chimeric mouse. In contrast, serum HBV level in adult Tupaia (1-year-old Tupaia) was quite low (<103 copies/ml). Understanding the differences in the response to HBV infection in primary Tupaia hepatocytes, chimeric mouse, and adult Tupaia will contribute to elucidating the mechanism of persistent HBV infection and viral eradication. Thus, T. belangeri was found to be efficient for studying the host response to HBV infection, thereby providing novel insight into the pathogenesis of HBV.
Takahiro Sanada - One of the best experts on this subject based on the ideXlab platform.
-
Avian H5N1 influenza virus infection causes severe pneumonia in the Northern tree shrew (Tupaia belangeri).
Virology, 2019Co-Authors: Takahiro Sanada, Mohammad Enamul Hoque Kayesh, Kyoko Tsukiyama-kohara, Fumihiko Yasui, Tomoko Honda, Jun-ichiro Takano, Yumiko Shiogama, Yasuhiro Yasutomi, Michinori KoharaAbstract:Avian-origin influenza viruses like H5N1 and H7N9 often cause severe symptoms with high mortality in humans. Animal models are useful for clarification of the mechanisms of pathogenicity of these infections. In this study, to expand the potential utility of the Northern tree shrew (Tupaia belangeri) for influenza virus infection, we assessed the pathogenicity of H5N1 and H7N9 avian influenza viruses in Tupaia. Infectious virus was detected continuously from nasal, oral, tracheal, and conjunctival swab samples in the animals infected with these viruses. H5N1 influenza virus infection of Tupaia caused severe diffuse pneumonia with fever and weight loss. In contrast, H7N9 influenza virus infection caused focal pneumonia. The severity of pneumonia was correlated with proinflammatory cytokine transcript levels. These results indicated that Tupaia can be another suitable animal model for avian influenza virus research.
-
Interferon-β response is impaired by hepatitis B virus infection in Tupaia belangeri.
Virus research, 2017Co-Authors: Mohammad Enamul Hoque Kayesh, Sayeh Ezzikouri, Haiying Chi, Takahiro Sanada, Naoki Yamamoto, Bouchra Kitab, Takumi Haraguchi, Rika Matsuyama, Chimène Nze Nkogue, Hitoshi HataiAbstract:To date, the chimpanzee has been used as the natural infection model for hepatitis B virus (HBV). However, as this model is very costly and difficult to use because of ethical and animal welfare issues, we aimed to establish the Tupaia (Tupaia belangeri) as a new model for HBV infection and characterized its intrahepatic innate immune response upon HBV infection. First, we compared the propagation of HBV genotypes A2 and C in vivo in Tupaia hepatocytes. At 8-10days post infection (dpi), the level of HBV-A2 propagation in the Tupaia liver was found to be higher than that of HBV-C. Abnormal architecture of liver cell cords and mitotic figures were also observed at 8 dpi with HBV-A2. Moreover, we found that HBV-A2 established chronic infection in some Tupaias. We then aimed to characterize the intrahepatic innate immune response in this model. First, we infected six Tupaias with HBV-A2 (strains JP1 and JP4). At 28 dpi, intrahepatic HBV-DNA and serum hepatitis B surface antigens (HBsAg) were detected in all Tupaias. The levels of interferon (IFN)-β were found to be significantly suppressed in the three Tupaias infected with HBV A2_JP4, while no significant change was observed in the three infected with HBV A2_JP1. Expression of toll-like receptor (TLR) 1 was suppressed, while that of TLR3 and TLR9 were induced, in HBV A2_JP1-infected Tupaias. Expression of TLR8 was induced in all Tupaias. Next, we infected nine Tupaias with HBV-A2 (JP1, JP2, and JP4), and characterized the infected animals after 31 weeks. Serum HBsAg levels were detected at 31 weeks post-infection (wpi) and IFN-β was found to be significantly suppressed in all Tupaias. TLR3 was not induced, except in Tupaia #93 and #96. Suppression of TLR9 was observed in all Tupaias, except Tupaia #93. Also, we investigated the expression levels of cyclic GMP-AMP synthase, which was found to be induced in all Tupaias at 28 dpi and in four Tupaias at 31 wpi. Additionally, we evaluated the expression levels of sodium-taurocholate cotransporting polypeptide, which was found to be suppressed during chronic HBV infection. Thus, the Tupaia infection model of HBV clearly indicated the suppression of IFN-β at 31 wpi, which might have contributed to the establishment of chronic HBV infection.
-
Susceptibility and initial immune response of Tupaia belangeri cells to dengue virus infection.
Infection genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases, 2017Co-Authors: Mohammad Enamul Hoque Kayesh, Takahiro Sanada, Bouchra Kitab, Michinori Kohara, Daisuke Hayasaka, Kouichi Morita, Kyoko Tsukiyama-koharaAbstract:Abstract Dengue is an emerging disease of great public health significance worldwide. The lack of a suitable infection model has hampered dengue virus (DENV) pathogenesis study, and developing a suitable small animal model has been a long-standing challenge. The aim of this study was to develop a feasible experimental model of DENV infection using Tupaia belangeri . The susceptibility of Tupaia to DENV infection and characteristics of its innate immune response were examined in vitro . We found that Tupaia fibroblast cells support replication of DENV serotypes 1–4 with a linear increase in viral load 24–96 h post-infection in both cells and culture supernatants. DENV-2 resulted in the highest viral growth among all serotypes. To characterize the innate immune response in Tupaia cells during the early phase of DENV infection, we first evaluated the evolutionary relationship between Tupaia Toll-like receptors (TLR1–9) and those of other mammalian species. Phylogenetic analysis showed that Tupaia TLRs are evolutionarily much closer to human than they are to rodent. We next established an innate immune response measurement system by assessing the mRNA expression of TLR1–9 and four cytokines in DENV-infected Tupaia cells. All serotypes induced the upregulation of TLR8 mRNA expression in infected Tupaia cells. Silencing of TLR8 led to an increase in viral replication, indicating the existence of antiviral response through TLR8 on DENV infection. Although upregulation of IFN-β and IL-6 expression was only observed in DENV-1 infected cells and a significant suppression of TNF-α was observed in DENV-2 infected cells alone, IL-8 was upregulated in all DENV-1–4. Thus, this study demonstrates for the first time the susceptibility of Tupaia cells to DENV infections and the role of TLR8 in the anti-viral response of Tupaia cells to DENV. These findings demonstrate the potential utility of Tupaia as a model for DENV research in the future.
-
Oxidative Stress and Immune Responses During Hepatitis C Virus Infection in Tupaia belangeri
Nature Publishing Group, 2017Co-Authors: Mohammad Enamul Hoque Kayesh, Sayeh Ezzikouri, Haiying Chi, Takahiro Sanada, Bouchra Kitab, Yukiko Hayashi, Khadija Rebbani, Aya Matsuu, Noriaki Miyoshi, Tsunekazu HishimaAbstract:Abstract Hepatitis C virus (HCV) is a leading cause of chronic liver disease, cirrhosis, and hepatocellular carcinoma. To address the molecular basis of HCV pathogenesis using Tupaias (Tupaia belangeri), we characterized host responses upon HCV infection. Adult Tupaias were infected with HCV genotypes 1a, 1b, 2a, or 4a. Viral RNA, alanine aminotransferase, anti-HCV core and anti-nonstructural protein NS3 antibody titres, reactive oxygen species (ROS), and anti-3β-hydroxysterol-Δ24reductase (DHCR24) antibody levels were measured at 2-week intervals from 0 to 41 weeks postinfection. All HCV genotypes established infections and showed intermittent HCV propagation. Moreover, all Tupaias produced anti-core and anti-NS3 antibodies. ROS levels in sera and livers were significantly increased, resulting in induction of DHCR24 antibody production. Similarly, lymphocytic infiltration, disturbance of hepatic cords, and initiation of fibrosis were observed in livers from HCV-infected Tupaias. Intrahepatic levels of Toll-like receptors 3, 7, and 8 were significantly increased in all HCV-infected Tupaias. However, interferon-β was only significantly upregulated in HCV1a- and HCV2a-infected Tupaias, accompanied by downregulation of sodium taurocholate cotransporting polypeptide. Thus, our findings showed that humoral and innate immune responses to HCV infection, ROS induction, and subsequent increases in DHCR24 auto-antibody production occurred in our Tupaia model, providing novel insights into understanding HCV pathogenesis
-
property of hepatitis b virus replication in Tupaia belangeri hepatocytes
Biochemical and Biophysical Research Communications, 2016Co-Authors: Takahiro Sanada, Sayeh Ezzikouri, Naoki Yamamoto, Soumaya Benjelloun, Shuko Murakami, Yasuhito Tanaka, Chise Tateno, Kyoko Tsukiyamakohara, Michinori KoharaAbstract:The northern treeshrew (Tupaia belangeri) has been reported to be an effective candidate for animal infection model with hepatitis B virus (HBV). The objective of our study was to analyze the growth characteristics of HBV in Tupaia hepatocytes and the host response to HBV infection. We established primary Tupaia hepatocytes (3–6-week old Tupaia) and infected them with HBV genotypes A, B and C, and all the genotypes proliferated as well as those in human primary hepatocytes (>105 copies/ml in culture supernatant). We next generated a chimeric mouse with Tupaia liver by transplantation of Tupaia primary hepatocytes to urokinase-type plasminogen activator cDNA (cDNA-uPA)/severe combined immunodeficient (SCID) mice and the replacement ratio with Tupaia hepatocytes was found to be more than 95%. Infection of chimeric mice with HBV (genotypes B, C, and D) resulted in HBV-DNA level of 104-106 copies/ml after 8 weeks of infection, which were almost similar to that in humanized chimeric mouse. In contrast, serum HBV level in adult Tupaia (1-year-old Tupaia) was quite low (<103 copies/ml). Understanding the differences in the response to HBV infection in primary Tupaia hepatocytes, chimeric mouse, and adult Tupaia will contribute to elucidating the mechanism of persistent HBV infection and viral eradication. Thus, T. belangeri was found to be efficient for studying the host response to HBV infection, thereby providing novel insight into the pathogenesis of HBV.
Lutz Walter - One of the best experts on this subject based on the ideXlab platform.
-
MHC class I genes of the tree shrew Tupaia belangeri.
Immunogenetics, 2002Co-Authors: Perris Flügge, Eberhard Fuchs, Eberhard Günther, Lutz WalterAbstract:Two MHC class I cDNA sequences from the tree shrew (Tupaia belangeri), Tube-W01 and Tube-W02, have been isolated which are probably derived from classical class I genes. Expression of the Tupaia class I genes was investigated in several organs, in particular the brain, in which slightly different amounts of class I transcripts are detectable in different areas. Gene tree analysis performed with Tube-W01 and Tube-W02, and including class I sequences derived from other orders, indicated that the Tupaia sequences cluster differently from Primates, Carnivora, Artiodactyla, Perissodactyla, and Rodentia, but might be related to Lagomorpha class I genes.
Jesus Prieto - One of the best experts on this subject based on the ideXlab platform.
-
hepatitis c virus infection of primary Tupaia hepatocytes leads to selection of quasispecies variants induction of interferon stimulated genes and nf κb nuclear translocation
Journal of General Virology, 2005Co-Authors: Anunciata Guitart, Maria P Civeira, Joseignacio Riezuboj, Edurne Elizalde, Esther Larrea, Carmen Berasain, Rafael Aldabe, Jesus PrietoAbstract:Systems for in vitro culture of Hepatitis C virus (HCV) are essential tools to analyse virus–cell interactions and to investigate relevant pathophysiological aspects of HCV infection. Although the HCV replicon methodology has increased our understanding of HCV biology, this system does not reproduce the natural infection. Recently, Tupaia (Tupaia belangeri chinensis) hepatocytes have been utilized for in vitro culture of HCV. In the present work, primary Tupaia hepatocytes infected in vitro with HCV were used to analyse the evolution of HCV quasispecies in infected cells and the ability of the virus to influence antiviral and proinflammatory responses in cells sustaining virus replication. The results confirmed the potential of Tupaia hepatocytes as a model for HCV infection, although this system is limited by rapid loss of differentiated cell phenotype in culture. These findings revealed an extraordinary plasticity of HCV quasispecies, which underwent rapid evolution to Tupaia-tropic variants as early as 24 h after infection. It was also shown that HCV could activate interferon-sensitive genes, albeit modestly in comparison with other viruses such as Semliki Forest virus. Importantly, HCV activated NF-κB in primary hepatocytes and upregulated NF-κB-responsive genes including the chemokines MCP-1 and CXCL2 (MIP-2). This effect may play a role in induction of the hepatic inflammatory reaction in vivo. In summary, HCV quasispecies adapt rapidly to the specific biology of the host and HCV stimulates a blunted interferon response while inducing a proinflammatory phenotype in the infected cell.
-
transmission of hepatitis c virus infection to tree shrews
Virology, 1998Co-Authors: Zhichun Xie, Jose I Riezuboj, Juan Jose Lasarte, J Guillen, Maria P Civeira, Jesus PrietoAbstract:Although hepatitis C virus (HCV) infection can be reproduced in chimpanzees, these animals are rare and expensive. Tree shrews (Tupaias) are small animals, closely related to primates, which adapt easily to a laboratory environment. In this work we have investigated the susceptibility of Tupaia belangeri chinensis to HCV infection. Tupaias caught in the wild in Yunnan (China) were inoculated in China with HCV genotype 1b (study A) and in Spain with a mixture of genotypes 1b, 1a, and 3 (study B). In study B Tupaias were divided into three groups: group I was inoculated without previous manipulation, group II received 750 cGy of X-ray whole-body irradiation before inoculation, and group III was used as control. Transient or intermittent viremia occurred in 34.8% (8/23) and anti-HCV in 30.4% (7/23) of Tupaias in study A. In study B a transient viremia was detected in 20% (2/10) in group I and in 50% (2/4) in group II. Anti-HCV was found in 1 Tupaia from group I and in 3 from group II. Viremia lasted for longer and anti-HCV tended to reach higher titers in animals which received total body irradiation. ALT elevations and nonspecific pathological changes occurred in inoculated Tupaias; however, the wild nature of the animals precludes the interpretation of these changes as solely due to HCV infection. In summary our results show that T. b. chinensis are susceptible to HCV and that whole-body irradiation may possibly increase the efficiency of the infection. These animals may serve as an in vivo system for culturing HCV and addressing pathophysiological and therapeutic issues of HCV infection. © 1998 Academic Press
Xiping Zhao - One of the best experts on this subject based on the ideXlab platform.
-
Suppression of hepatitis B virus replication in Tupaia hepatocytes by tumor necrosis factor alpha of Tupaia belangeri.
Comparative immunology microbiology and infectious diseases, 2011Co-Authors: Josef Köck, Dongliang Yang, Xiping ZhaoAbstract:Recently, Tupaia belangeri was used to study the full replication cycle of hepatitis B virus (HBV) in the primary hepatocyte cultures. Thus, the Tupaia model represents a suitable model to study the effects of cytokines on HBV infection. Here, Tupaia tumor necrosis factor-alpha (TNF-α) was molecularly cloned and expressed in mammalian cells. A test system for the biological activity of Tupaia TNF-α was established on the basis of its cytotoxic effect to the murine fibrosarcoma cell line L929. Recombinant Tupaia TNF-α was able to suppress HBV replication in primary Tupaia hepatocytes (PTH). However, the formation of HBV covalently closed circular DNA (cccDNA) and viral RNA was not completely prevented. Therefore, Tupaia TNF-α may contribute significantly to the control of HBV infection though it is not able to completely inhibit HBV replication alone. The characterization of this important cytokine allows further studies on its antiviral actions in the Tupaia model.
-
Interaction of hepatitis C virus envelope glycoprotein E2 with the large extracellular loop of Tupaia CD81.
World Journal of Gastroenterology, 2009Co-Authors: Zhan-fei Tian, Hong Shen, Yi-chun Chen, Hubert E. Blum, Thomas Baumert, Xiping ZhaoAbstract:AIM: To further analyze the interaction of Tupaia CD81 with hepatitis C virus (HCV) envelope protein E2. METHODS: A Tupaia CD81 large extracellular loop (CD81 LEL), which binds to HCV E2 protein, was cloned and expressed as a GST-fusion protein, and interaction of HCV E2 protein with a Tupaia CD81 LEL was evaluated by enzyme-linked immunosorbent assay (EIA). RESULTS: Although Tupaia and human CD81 LEL differed in 6 amino acid changes, Tupaia CD81 LEL was strongly recognized by anti-CD81 antibodies against human CD81 LEL conformation-dependent epitopes. Investigating LEL CD81-E2 interactions by EIA, we demonstrated that binding of Tupaia CD81 LEL GST fusion protein to recombinant HCV E2 protein was markedly reduced compared to binding of human CD81 LEL GST fusion protein to recombinant HCV E2 protein. CONCLUSION: These data suggest that the structural differences in-between the Tupaia and human CD81 may alter the interaction of the large extracellular loop with HCV envelope glycoprotein E2. These findings may be important for the understanding of the mechanisms of binding and entry of HCV to PTHs.
-
Scavenger receptor class B type I and hepatitis C virus infection of primary Tupaia hepatocytes.
Journal of virology, 2005Co-Authors: Heidi Barth, Xiping Zhao, Raffaele Cerino, Mirko Arcuri, Marco Hoffmann, Peter Schürmann, Mohammed I. Adah, B. Gissler, Valeria Ghisetti, Bruna LavezzoAbstract:Hepatitis C virus (HCV) is a major cause of chronic hepatitis worldwide. The study of early steps during HCV infection has been hampered by the lack of suitable in vitro or in vivo models. Primary Tupaia hepatocytes (PTH) have been shown to be susceptible to HCV infection in vitro and in vivo. Human scavenger receptor class B type I (SR-BI) represents an HCV receptor candidate mediating the cellular binding of E2 glycoprotein to HepG2 hepatoma cells. However, the function of SR-BI for viral infection of hepatocytes is unknown. In this study, we used PTH to assess the functional role of SR-BI as a putative HCV receptor. Sequence analysis of cloned Tupaia SR-BI revealed a high homology between Tupaia and human SR-BI. Transfection of CHO cells with human or Tupaia SR-BI but not mouse SR-BI cDNA resulted in cellular E2 binding, suggesting that E2-binding domains between human and Tupaia SR-BI are highly conserved. Preincubation of PTH with anti-SR-BI antibodies resulted in marked inhibition of E2 or HCV-like particle binding. However, anti-SR-BI antibodies were not able to block HCV infection of PTH. In conclusion, our results demonstrate that SR-BI represents an important cell surface molecule for the binding of the HCV envelope to hepatocytes and suggest that other or additional cell surface molecules are required for the initiation of HCV infection. Furthermore, the structural and functional similarities between human and Tupaia SR-BI indicate that PTH represent a useful model system to characterize the molecular interaction of the HCV envelope and SR-BI on primary hepatocytes.
-
Primary hepatocytes of Tupaia belangeri as a potential model for hepatitis C virus infection
The Journal of clinical investigation, 2002Co-Authors: Xiping Zhao, Hubert E. Blum, Fritz Von Weizsäcker, Zhen Ya Tang, Bettina Klumpp, Guido Wolff-vorbeck, Heidi Barth, Shoshana Levy, Thomas BaumertAbstract:Hepatitis C virus (HCV) is a major cause of chronic hepatitis worldwide, but the study of HCV infection has been hampered by the lack of an in vitro or in vivo small animal model. The tree shrew Tupaia belangeri is susceptible to infection with a variety of human viruses in vivo, including hepatitis viruses. We show that primary Tupaia hepatocytes can be infected with serum- or plasma-derived HCV from infected humans, as measured by de novo synthesis of HCV RNA, analysis of viral quasispecies evolution, and detection of viral proteins. Production of infectious virus could be demonstrated by passage to naive hepatocytes. To assess whether viral entry in Tupaia hepatocytes was dependent on the recently isolated HCV E2 binding protein CD81, we identified and characterized Tupaia CD81. Sequence analysis of cloned Tupaia cDNA revealed a high degree of homology between Tupaia and human CD81 large extracellular loops (LEL). Cellular binding of E2 and HCV infection could not be inhibited by anti-CD81 antibodies or soluble CD81-LEL, suggesting that viral entry can occur through receptors other than CD81. Thus, primary Tupaia hepatocytes provide a potential model for the study of HCV infection of hepatocytes.
