| 1. |
- Ahlen, Gustaf, et al.
(författare)
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Limited effect on NS3-NS4A protein cleavage after alanine substitutions within the immunodominant HLA-A2-restricted epitope of the hepatitis C virus genotype 3a non-structural 3/4A protease.
- 2012
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Ingår i: The Journal of general virology. - : Microbiology Society. - 1465-2099 .- 0022-1317. ; 93:Pt 8, s. 1680-1686
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Tidskriftsartikel (refereegranskat)abstract
- It has been well established that immunological escape mutations within the hepatitis C virus genotype (gt) 1a non-structural (NS) 3/4A protease is partly prevented by a reduction of the viral protease fitness. Surprisingly little is known whether similar mutations affect proteases from other genotypes. In the present study, we assessed both the human leukocyte antigen (HLA)-A2-restricted cytotoxic T cell response and gt3a NS3/4A protease fitness. Similar to gt1, the 1073-1081 epitope was also immunodominant within the gt3a-specific HLA-A2-restricted cytotoxic T cell response, despite a homology of only 56% between gt1a and gt3a genes. However, unlike the gt1a NS3/4A protease, all residues within the gt3a 1073-1081 epitope could sequentially be replaced by alanine with a, at least in part, retained protease activity.
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| 2. |
- Asghar, Naveed, 1983-, et al.
(författare)
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DNA launched suicidal flaviviruses as therapeutic vaccine candidates
- 2018
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Konferensbidrag (refereegranskat)abstract
- Chronic liver disease, resulting from Hepatitis B virus (HBV), Hepatitis D virus (HDV), or Hepatitis C virus (HCV) infections, contributes to a major health burden worldwide. The relativelyhigh cost of the HCV treatment brings concerns about the accessibility, especially in the developing countries. Hence, there exists a need for cost effect interventions with high efficiency. We aim to develop therapeutic vaccine candidates against HBV, HCV and HDV using DNA based subgenomic flavivirus replicons as a delivery system. Tick-borne encephalitis virus (TBEV), Langat virus (LGTV), West-Nile virus (WNV), or Kunjinvirus (KUNV) replicon with firefly luciferase geneas a reporter were expressed and characterized in cell culture studies. WNV and KUNV replicons showed significantly higher replication compared to their respective negative controls with unfunctional viral RNA dependent RNA polymerase. KUNV and WNV replicons were chosen for cloning the HCV or HB/DV vaccine candidate gene by replacing luciferasegene. Owing to the self-replicating trait of the flavivirus subgenomic replicons, Western blotting demonstrated that the antigen expression by KUNV and WNV replicons was several folds higher than the positive control. These results suggest that DNA based KUNV and WNV replicons may function as carriers for the hepatitis vaccine candidate genes, and these replicons are currently used for in vivostudies in animal models.
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| 3. |
- Asghar, Naveed, 1983-, et al.
(författare)
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Immunogenicity of DNA launched suicidal flavivirus replicons for protective vaccination against hepatitis viruses
- 2019
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Konferensbidrag (refereegranskat)abstract
- Chronic liver disease, resulting from Hepatitis B virus (HBV), Hepatitis D virus (HDV), or Hepatitis C virus (HCV) infections, contributes to a major health burden worldwide. Chronic infections with the hepatitis C virus (HCV) can be effectively cured by antivirals. However, as cured patients can be re-infected they lack protective immune responses. In addition, the relativelyhigh cost of the HCV treatment brings concerns about the accessibility, especially in the developing countries. Hence, there exists a need for cost effect vaccines with high efficiency to control and possibly eradicate Hepatitis viruses globally. The vaccine should induce either, or both, neutralizing antibodies and protective T cell responses. We therefore have developed DNA based flavivirus replicons as a potent delivery system that effectively prime HCV-specific T cell responses. We generated suicidal subgenomic DNA replicons of Tick-borne encephalitis virus (TBEV), Langat virus (LGTV), West-Nile virus (WNV), and Kunjinvirus (KUNV) expressing either a fusion protein between the HCV NS3/4A and a stork hepatitis B virus core or a vaccine candidate gene of HB/DV. Transfection experiments showed that the antigen expression by KUNV and WNV replicons was several folds higher than the antigen expression by standard DNA plasmid with CMV promoter. The immunogenicity of three suicidal flaviviral DNA replicons expressing HCV NS3/4A was tested in mice and compared to HCV NS3/4A expression by the standard DNA plasmid. The KUNV-HCV replicon was the best replicon-based immunogen with respect to priming of HCV NS3/4A-specific T cells as determined by ELISpot, dextramer staining, and polyfunctionality. Importantly, a mutant KUNV-HCV immunogen lacking replication failed to induce immune responses. Thus, the newly developed KUNV-based suicidal DNA launched replicon vaccine for HCV is a highly attractive candidate as a prophylactic vaccine against chronic hepatitis C. In addition, we are currently testing the immunogenicity of KUNV-HB/DV replicon in mice.
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| 4. |
- Brenndörfer, Erwin Daniel, et al.
(författare)
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Hepatitis C virus non-structural 3/4A protein interferes with intrahepatic interferon-γ production.
- 2012
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Ingår i: Gut. - : BMJ. - 1468-3288 .- 0017-5749. ; 61:4, s. 589-96
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Tidskriftsartikel (refereegranskat)abstract
- The non-structural (NS) 3/4A protease/helicase of the hepatitis C virus is known to modulate signalling pathways in the infected hepatocyte by cleaving CARD adaptor inducing IFNβ (Cardif), T-cell protein tyrosine phosphatase (TC-PTP) and TIR domain-containing adaptor inducing IFNβ (TRIF), but the effects of NS3/4A in vivo still remain unclear.
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| 5. |
- Burm, Rani, et al.
(författare)
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Novel prime-boost immune-based therapy inhibiting both hepatitis B and D virus infections.
- 2023
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Ingår i: Gut. - : BMJ Publishing Group Ltd. - 0017-5749 .- 1468-3288. ; 72:6, s. 1186-1195
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Chronic HBV/HDV infections are a major cause of liver cancer. Current treatments can only rarely eliminate HBV and HDV. Our previously developed preS1-HDAg immunotherapy could induce neutralising antibodies to HBV in vivo and raise HBV/HDV-specific T-cells. Here, we further investigate if a heterologous prime-boost strategy can circumvent T-cell tolerance and preclude HDV superinfection in vivo.DESIGN: A DNA prime-protein boost strategy was evaluated for immunogenicity in mice and rabbits. Its ability to circumvent T-cell tolerance was assessed in immunocompetent hepatitis B surface antigen (HBsAg)-transgenic mice. Neutralisation of HBV and HDV was evaluated both in vitro and in immunodeficient human-liver chimeric mice upon adoptive transfer.RESULTS: The prime-boost strategy elicits robust HBV/HDV-specific T-cells and preS1-antibodies that can effectively prevent HBV and HDV (co-)infection in vitro and in vivo. In a mouse model representing the chronic HBsAg carrier state, active immunisation primes high levels of preS1-antibodies and HDAg-specific T-cells. Moreover, transfer of vaccine-induced antibodies completely protects HBV-infected human-liver chimeric mice from HDV superinfection.CONCLUSION: The herein described preS1-HDAg immunotherapy is shown to be immunogenic and vaccine-induced antibodies are highly effective at preventing HBV and HDV (super)infection both in vitro and in vivo. Our vaccine can complement current and future therapies for the control of chronic HBV and HDV infection.
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| 6. |
- Chen, Antony, et al.
(författare)
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Heterologous T cells can help restore function in dysfunctional hepatitis C virus nonstructural 3/4A-specific T cells during therapeutic vaccination.
- 2011
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Ingår i: Journal of immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 186:9, s. 5107-18
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Tidskriftsartikel (refereegranskat)abstract
- The hepatitis C virus (HCV)-specific T cell response in patients with chronic HCV is dysfunctional. In this study, we aimed at restoring immunological function through therapeutic vaccination in a transgenic mouse model with impaired HCV-specific T cell responses due to a persistent presence of hepatic HCV nonstructural (NS)3/4A Ags. The HCV-specific T cells have an actively maintained dysfunction reflected in reduced frequency, impaired cytokine production, and impaired effector function in vivo, which can be partially restored by blocking regulatory T cells or programmed cell death ligand 1. We hypothesized that the impairment could be corrected by including sequences that created a normal priming environment by recruiting "healthy" heterologous T cells and by activating innate signaling. Endogenously expressed hepatitis B core Ag (HBcAg) can recruit heterologous T cells and activate TLR (TLR7) signaling. Hence, by combining HCV NS3/4A with different forms of HBcAg we found that heterologous sequences somewhat improved activation and expansion of NS3/4A-specific T cells in a wild-type host. Importantly, the signals provided by HBcAg effectively restored the activation of HCV-specific T cells in a tolerant NS3/4A-transgenic mouse model. The adjuvant effect could also be transferred to the priming of dysfunctional HLA-A2-restricted NS3-specific T cells in vivo. Thus, recruiting healthy heterologous T cells to the site of priming may also help restore HCV-specific responses present in a chronically infected host.
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| 7. |
- Einberg, Afrodite Psaros, et al.
(författare)
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Lack of association between interleukin 28B polymorphism and vertical transmission of hepatitis C
- 2017
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Ingår i: Journal of Pediatric Gastroenterology and Nutrition - JPGN. - : Lippincott Williams & Wilkins. - 0277-2116 .- 1536-4801. ; 65:6, s. 608-612
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Single genetic nucleotide polymorphism (rs12979860) near the gene for Interleukin 28B (IL28B), is known to be of importance for frequency of spontaneous clearance and treatment outcome in interferon based therapies in patients with hepatitis C virus (HCV) infection. The aim of this study was to investigate if IL28B polymorphism in children and/or their mothers plays a role in vertical transmission of HCV (HCV-VT).METHODS: Plasma samples from 59 infected women, 76 uninfected children born to infected mothers, and 47 children with known vertically transmitted HCV infection, were analysed for IL28B polymorphism and classified by the IL28B genotype (C/C, C/T and T/T) as well as by viral genotype.RESULTS: The proportion of children with genotype C/C was the same in the vertically infected (36%, 17/47) and the exposed uninfected children (38%, 29/76). No difference was seen when stratifying for viral genotype. There was no association between mothers' IL28B genotype and the risk of vertical transmission.CONCLUSION: Regardless of viral genotype we found no association between IL28B genotype and the risk of HCV-VT. The IL28B genotype CC, which has been shown to be favourable in other settings, was not protective of HCV-VT. Thus, other factors possibly associated with the risk of HCV-VT need to be explored.
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| 8. |
- Frelin, Johanna, et al.
(författare)
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Perspektiv på förändringsledarskap
- 2013
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Ingår i: Perspektiv på förändring : om en förändringsresa på Sveriges Television. - : Stockholm School of Economics Institute for Research. - 9789186797096
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Frelin, Lars
(författare)
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Development of vaccines and experimental models for chronic infections caused by the hepatitis C virus
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The hepatitis C virus (HCV) is a major cause of chronic liver disease worldwide. It is estimated that HCV affects approximately 170 million people around the world. One feature of HCV infection is the high rate of viral persistence. The mechanism of viral persistence is largely unknown, although the high genetic variability is thought to play a key role. Today, no vaccine is available to prevent or cure HCV infections, albeit antiviral therapy is used quite effectively. This study aimed at developing new vaccines and new model systems to study HCV. We studied the HCV NS3 protein in detail since it performs key functions in the viral life cycle. These are unwinding and strand separation of the viral RNA and proteolytic processing of the precursor polyprotein. To obtain the complete protease we included the NS4A co-factor in our NS3-based vaccines. NS4A has been shown to enhance the stability of NS3 and to target the NS3/4A complex to intracellular membranes. The latter is most likely of importance for the formation of the replication complex. Also, the NS3 region has a limited genetic variability and several studies have now demonstrated that NS3-specific CD4+ and CD8+ T-cell responses are crucial for the resolution of HCV infections. Thus, several factors suggest that the NS3 region should be well suited for vaccine development. We could show that HCV NS3-based genetic vaccines effectively primed both humoral and cellular immune responses in mice. NS3/4A was shown to prime a Th1 CD4+ T-cell responses. The inclusion of NS4A in NS3-based vaccines primed antibody, CD4+, and CD8+ T-cell responses that were superior to those primed by NS3-gene alone. Thus, NS4A enhanced the immunogenicity of NS3. We could show that enhancement of the immunogenicity was most probably a result of the higher expression levels of NS3 generated by the inclusion of NS4A. We next tested if the overall immunogenicity of NS3/4A could be further enhanced by codon optimization or by mRNA amplification using the Semliki forest virus (SFV) replicon. The NS3 protein expression levels were further improved by either codon optimization and mRNA amplification. Subsequently, both these modifications enhanced the NS3-specific immune responses. One concern in development of genetic vaccines is that the gene displays unwanted properties when expressed in vivo. We therefore, generated a new transgenic mouse expressing the HCV NS3/4Aprotein in the liver. The protein expression was restricted to the liver to mimic the in vivo situation during a HCV infection. Protein expression was localized to the cytoplasm of the hepatocytes and displayed a similar staining pattern as seen in hepatocytes from HCV infected individuals. The intrahepatic protein expression did not cause overt liver damage, except for a slight enlargement of the liver. However, the NS3/4A-transgenic mice displayed less spontaneously appearing intrahepatic inflammatory foci, which are commonly found in laboratory mice. Thus, expression of NS3/4A-protein may affect the distribution of immune cells within the liver. The present studies demonstrate that NS3-based genetic vaccines that contain NS4A more effectively prime humoral and cellular immune responses against NS3. Intra-hepatic expression of NS3/4A did not cause any spontaneous liver disease or overt pathology suggesting that it safely can be used in genetic vaccines. Thus, the NS3/4A gene can safely activate immune responses that are similar to those found in humans who can clear HCV. The NS3/4A should therefore be a potential vaccine candidate against chronic HCV infections.
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| 10. |
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