The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Bud C. Tennant - One of the best experts on this subject based on the ideXlab platform.
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electroporation enhances immunogenicity of a dna vaccine expressing Woodchuck Hepatitis virus surface antigen in Woodchucks
Journal of Virology, 2011Co-Authors: Katherine H Liu, Paul J Cote, Christine A Bellezza, Mary Ascenzi, Alain Luxembourg, Drew Hannaman, Gloria Gonzalezaseguinolaza, Abraham J Bezuidenhout, Claire F Evans, Bud C. TennantAbstract:The development of therapeutic vaccines for chronic Hepatitis B virus (HBV) infection has been hampered by host immune tolerance and the generally low magnitude and inconsistent immune responses to conventional vaccines and proposed new delivery methods. Electroporation (EP) for plasmid DNA (pDNA) vaccine delivery has demonstrated the enhanced immunogenicity of HBV antigens in various animal models. In the present study, the efficiency of the EP-based delivery of pDNA expressing various reporter genes first was evaluated in normal Woodchucks, and then the immunogenicity of an analog Woodchuck Hepatitis virus (WHV) surface antigen (WHsAg) pDNA vaccine was studied in this model. The expression of reporter genes was greatly increased when the cellular uptake of pDNA was facilitated by EP. The EP of WHsAg-pDNA resulted in enhanced, dose-dependent antibody and T-cell responses to WHsAg compared to those of the conventional hypodermic needle injection of WHsAg-pDNA. Although subunit WHsAg protein vaccine elicited higher antibody titers than the DNA vaccine delivered with EP, T-cell response rates were comparable. However, in WHsAg-stimulated mononuclear cell cultures, the mRNA expression of CD4 and CD8 leukocyte surface markers and Th1 cytokines was more frequent and was skewed following DNA vaccination compared to that of protein immunization. Thus, the EP-based vaccination of normal Woodchucks with pDNA-WHsAg induced a skew in the Th1/Th2 balance toward Th1 immune responses, which may be considered more appropriate for approaches involving therapeutic vaccines to treat chronic HBV infection.
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electroporation enhances immunogenicity of a dna vaccine expressing Woodchuck Hepatitis virus surface antigen in Woodchucks
Journal of Virology, 2011Co-Authors: Mary Ascenzi, Bud C. Tennant, Paul J Cote, Christine A Bellezza, Alain Luxembourg, Drew Hannaman, Gloria Gonzalezaseguinolaza, Abraham J Bezuidenhout, Claire F Evans, Stephan MenneAbstract:The development of therapeutic vaccines for chronic Hepatitis B virus (HBV) infection has been hampered by host immune tolerance and the generally low magnitude and inconsistent immune responses to conventional vaccines and proposed new delivery methods. Electroporation (EP) for plasmid DNA (pDNA) vaccine delivery has demonstrated the enhanced immunogenicity of HBV antigens in various animal models. In the present study, the efficiency of the EP-based delivery of pDNA expressing various reporter genes first was evaluated in normal Woodchucks, and then the immunogenicity of an analog Woodchuck Hepatitis virus (WHV) surface antigen (WHsAg) pDNA vaccine was studied in this model. The expression of reporter genes was greatly increased when the cellular uptake of pDNA was facilitated by EP. The EP of WHsAg-pDNA resulted in enhanced, dose-dependent antibody and T-cell responses to WHsAg compared to those of the conventional hypodermic needle injection of WHsAg-pDNA. Although subunit WHsAg protein vaccine elicited higher antibody titers than the DNA vaccine delivered with EP, T-cell response rates were comparable. However, in WHsAg-stimulated mononuclear cell cultures, the mRNA expression of CD4 and CD8 leukocyte surface markers and Th1 cytokines was more frequent and was skewed following DNA vaccination compared to that of protein immunization. Thus, the EP-based vaccination of normal Woodchucks with pDNA-WHsAg induced a skew in the Th1/Th2 balance toward Th1 immune responses, which may be considered more appropriate for approaches involving therapeutic vaccines to treat chronic HBV infection.
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rapid immunity to vaccination with Woodchuck Hepatitis virus surface antigen using cationic liposome dna complexes as adjuvant
Journal of Medical Virology, 2009Co-Authors: Paul J Cote, Bud C. Tennant, John L Gerin, Scott D Butler, Andrea L George, Jeffery Fairman, Stephan MenneAbstract:Complexes of cationic liposomes and non-coding DNA (CLDC) have shown promise as vaccine adjuvant. Using the Woodchuck animal model of Hepatitis B virus (HBV) infection, the immunogenic effects of CLDC were evaluated following vaccination with three doses of Woodchuck Hepatitis virus surface antigen (WHsAg) adjuvanted with either CLDC or conventional alum and administered intramuscularly (im) or subcutaneously (sc). IM vaccination with WHsAg and CLDC elicited antibodies earlier, in more Woodchucks, and with higher titers than WHsAg and alum. After two vaccine doses, antibody titers were higher following im than sc administration. Woodchucks administered two vaccine doses sc received the third vaccine dose im, and antibody responses reached titers comparable to those elicited by im administration. Following the second vaccine dose, im vaccination with WHsAg and CLDC induced T cell responses to WHsAg and selected WHs peptides and expression of the leukocyte surface marker CD8 and of the Th1 cytokines interferon-gamma and tumor necrosis factor alpha in Woodchucks. T cell responses and CD8/cytokine expression were diminished in Woodchucks from the other groups suggesting that this vaccine regimen induced a skew toward Th1 immune responses. The present study in Woodchucks demonstrates that CLDC-adjuvanted WHsAg vaccine administered im resulted in a more rapid induction of humoral and cellular immune responses compared to conventional, alum-adjuvanted WHsAg vaccine. While less rapid, the immune responses following sc administration can prime the im immune responses. This adjuvant activity of CLDC over alum may be beneficial for therapeutic vaccination in chronic HBV infection. J. Med. Virol. 81:1760–1772, 2009. © 2009 Wiley-Liss, Inc.
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correlation of virus and host response markers with circulating immune complexes during acute and chronic Woodchuck Hepatitis virus infection
Journal of Virology, 2009Co-Authors: Dieter Glebe, Bud C. Tennant, Paul J Cote, Ilia A Tochkov, Scott D Butler, Wolfram H Gerlich, Heike Lorenz, Stephan MenneAbstract:Woodchuck Hepatitis virus (WHV) is an established model for human Hepatitis B virus. The kinetics of virus and host responses in serum and liver during acute, self-limited WHV infection in adult Woodchucks were studied. Serum WHV DNA and surface antigen (WHsAg) were detected as early as 1 to 3 weeks following experimental infection and peaked between 1 and 5 weeks postinfection. Thereafter, serum WHsAg levels declined rapidly and became undetectable, while WHV DNA levels became undetectable much later, between 4 and 20 weeks postinfection. Decreasing viremia correlated with transient liver injury marked by an increase in serum sorbitol dehydrogenase (SDH) levels. Clearance of WHV DNA from serum was associated with the normalization of serum SDH. Circulating immune complexes (CICs) of WHsAg and antibodies against WHsAg (anti-WHs) that correlated temporarily with the peaks in serum viremia and WHs antigenemia were detected. CICs were no longer detected in serum once free anti-WHs became detectable. The detection of CICs around the peak in serum viremia and WHs antigenemia in resolving Woodchucks suggests a critical role for the humoral immune response against WHsAg in the early elimination of viral and subviral particles from the peripheral blood. Individual kinetic variation during WHV infections in resolving Woodchucks infected with the same WHV inoculum and dose is likely due to the outbred nature of the animals, indicating that the onset and magnitude of the individual immune response determine the intensity of virus inhibition and the timing of virus elimination from serum.
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immunogenicity in mice and rabbits of dna vaccines expressing Woodchuck Hepatitis virus antigens
Vaccine, 2008Co-Authors: Alain Luxembourg, Bud C. Tennant, Ken Wills, Robert M Bernard, Drew Hannaman, Stephan Menne, Paul J CoteAbstract:Abstract The licensed vaccine against Hepatitis B virus (HBV) is an effective means to prevent infection, but is not an effective therapeutic strategy to treat established chronic infections when used alone. In an animal model of chronic HBV infection (the Woodchuck experimentally infected with Woodchuck Hepatitis virus (WHV)), the combination of conventional vaccine and potent antiviral drugs has shown promise as a potential therapeutic intervention. This approach might be improved further through the application of newer vaccine technologies. In the present study, we evaluated electroporation (EP)-based intramuscular (i.m.) delivery of a codon-optimized DNA vaccine for the WHV surface antigen (WHsAg) in mice and rabbits. In mice, this immunization procedure compared favorably to vaccination by i.m. injection of the DNA vaccine or i.m. administration of a recombinant WHsAg–alum vaccine, exhibiting characteristics expected to be beneficial for a therapeutic vaccine strategy. These included dose efficiency, consistency, vigorous induction of antibody responses to WHsAg, as well as a Th1 bias. Following scale-up to rabbits, a species that approximates the size of the Woodchuck, the EP dosing regimen was markedly more effective than conventional i.m. injection of the DNA vaccine. Taken together, these results provide the foundation for studies of EP-based DNA immunization in the Woodchuck in order to further assess its potential as an immunotherapeutic approach for treatment of chronic HBV infection in humans.
Paul J Cote - One of the best experts on this subject based on the ideXlab platform.
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electroporation enhances immunogenicity of a dna vaccine expressing Woodchuck Hepatitis virus surface antigen in Woodchucks
Journal of Virology, 2011Co-Authors: Katherine H Liu, Paul J Cote, Christine A Bellezza, Mary Ascenzi, Alain Luxembourg, Drew Hannaman, Gloria Gonzalezaseguinolaza, Abraham J Bezuidenhout, Claire F Evans, Bud C. TennantAbstract:The development of therapeutic vaccines for chronic Hepatitis B virus (HBV) infection has been hampered by host immune tolerance and the generally low magnitude and inconsistent immune responses to conventional vaccines and proposed new delivery methods. Electroporation (EP) for plasmid DNA (pDNA) vaccine delivery has demonstrated the enhanced immunogenicity of HBV antigens in various animal models. In the present study, the efficiency of the EP-based delivery of pDNA expressing various reporter genes first was evaluated in normal Woodchucks, and then the immunogenicity of an analog Woodchuck Hepatitis virus (WHV) surface antigen (WHsAg) pDNA vaccine was studied in this model. The expression of reporter genes was greatly increased when the cellular uptake of pDNA was facilitated by EP. The EP of WHsAg-pDNA resulted in enhanced, dose-dependent antibody and T-cell responses to WHsAg compared to those of the conventional hypodermic needle injection of WHsAg-pDNA. Although subunit WHsAg protein vaccine elicited higher antibody titers than the DNA vaccine delivered with EP, T-cell response rates were comparable. However, in WHsAg-stimulated mononuclear cell cultures, the mRNA expression of CD4 and CD8 leukocyte surface markers and Th1 cytokines was more frequent and was skewed following DNA vaccination compared to that of protein immunization. Thus, the EP-based vaccination of normal Woodchucks with pDNA-WHsAg induced a skew in the Th1/Th2 balance toward Th1 immune responses, which may be considered more appropriate for approaches involving therapeutic vaccines to treat chronic HBV infection.
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electroporation enhances immunogenicity of a dna vaccine expressing Woodchuck Hepatitis virus surface antigen in Woodchucks
Journal of Virology, 2011Co-Authors: Mary Ascenzi, Bud C. Tennant, Paul J Cote, Christine A Bellezza, Alain Luxembourg, Drew Hannaman, Gloria Gonzalezaseguinolaza, Abraham J Bezuidenhout, Claire F Evans, Stephan MenneAbstract:The development of therapeutic vaccines for chronic Hepatitis B virus (HBV) infection has been hampered by host immune tolerance and the generally low magnitude and inconsistent immune responses to conventional vaccines and proposed new delivery methods. Electroporation (EP) for plasmid DNA (pDNA) vaccine delivery has demonstrated the enhanced immunogenicity of HBV antigens in various animal models. In the present study, the efficiency of the EP-based delivery of pDNA expressing various reporter genes first was evaluated in normal Woodchucks, and then the immunogenicity of an analog Woodchuck Hepatitis virus (WHV) surface antigen (WHsAg) pDNA vaccine was studied in this model. The expression of reporter genes was greatly increased when the cellular uptake of pDNA was facilitated by EP. The EP of WHsAg-pDNA resulted in enhanced, dose-dependent antibody and T-cell responses to WHsAg compared to those of the conventional hypodermic needle injection of WHsAg-pDNA. Although subunit WHsAg protein vaccine elicited higher antibody titers than the DNA vaccine delivered with EP, T-cell response rates were comparable. However, in WHsAg-stimulated mononuclear cell cultures, the mRNA expression of CD4 and CD8 leukocyte surface markers and Th1 cytokines was more frequent and was skewed following DNA vaccination compared to that of protein immunization. Thus, the EP-based vaccination of normal Woodchucks with pDNA-WHsAg induced a skew in the Th1/Th2 balance toward Th1 immune responses, which may be considered more appropriate for approaches involving therapeutic vaccines to treat chronic HBV infection.
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rapid immunity to vaccination with Woodchuck Hepatitis virus surface antigen using cationic liposome dna complexes as adjuvant
Journal of Medical Virology, 2009Co-Authors: Paul J Cote, Bud C. Tennant, John L Gerin, Scott D Butler, Andrea L George, Jeffery Fairman, Stephan MenneAbstract:Complexes of cationic liposomes and non-coding DNA (CLDC) have shown promise as vaccine adjuvant. Using the Woodchuck animal model of Hepatitis B virus (HBV) infection, the immunogenic effects of CLDC were evaluated following vaccination with three doses of Woodchuck Hepatitis virus surface antigen (WHsAg) adjuvanted with either CLDC or conventional alum and administered intramuscularly (im) or subcutaneously (sc). IM vaccination with WHsAg and CLDC elicited antibodies earlier, in more Woodchucks, and with higher titers than WHsAg and alum. After two vaccine doses, antibody titers were higher following im than sc administration. Woodchucks administered two vaccine doses sc received the third vaccine dose im, and antibody responses reached titers comparable to those elicited by im administration. Following the second vaccine dose, im vaccination with WHsAg and CLDC induced T cell responses to WHsAg and selected WHs peptides and expression of the leukocyte surface marker CD8 and of the Th1 cytokines interferon-gamma and tumor necrosis factor alpha in Woodchucks. T cell responses and CD8/cytokine expression were diminished in Woodchucks from the other groups suggesting that this vaccine regimen induced a skew toward Th1 immune responses. The present study in Woodchucks demonstrates that CLDC-adjuvanted WHsAg vaccine administered im resulted in a more rapid induction of humoral and cellular immune responses compared to conventional, alum-adjuvanted WHsAg vaccine. While less rapid, the immune responses following sc administration can prime the im immune responses. This adjuvant activity of CLDC over alum may be beneficial for therapeutic vaccination in chronic HBV infection. J. Med. Virol. 81:1760–1772, 2009. © 2009 Wiley-Liss, Inc.
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correlation of virus and host response markers with circulating immune complexes during acute and chronic Woodchuck Hepatitis virus infection
Journal of Virology, 2009Co-Authors: Dieter Glebe, Bud C. Tennant, Paul J Cote, Ilia A Tochkov, Scott D Butler, Wolfram H Gerlich, Heike Lorenz, Stephan MenneAbstract:Woodchuck Hepatitis virus (WHV) is an established model for human Hepatitis B virus. The kinetics of virus and host responses in serum and liver during acute, self-limited WHV infection in adult Woodchucks were studied. Serum WHV DNA and surface antigen (WHsAg) were detected as early as 1 to 3 weeks following experimental infection and peaked between 1 and 5 weeks postinfection. Thereafter, serum WHsAg levels declined rapidly and became undetectable, while WHV DNA levels became undetectable much later, between 4 and 20 weeks postinfection. Decreasing viremia correlated with transient liver injury marked by an increase in serum sorbitol dehydrogenase (SDH) levels. Clearance of WHV DNA from serum was associated with the normalization of serum SDH. Circulating immune complexes (CICs) of WHsAg and antibodies against WHsAg (anti-WHs) that correlated temporarily with the peaks in serum viremia and WHs antigenemia were detected. CICs were no longer detected in serum once free anti-WHs became detectable. The detection of CICs around the peak in serum viremia and WHs antigenemia in resolving Woodchucks suggests a critical role for the humoral immune response against WHsAg in the early elimination of viral and subviral particles from the peripheral blood. Individual kinetic variation during WHV infections in resolving Woodchucks infected with the same WHV inoculum and dose is likely due to the outbred nature of the animals, indicating that the onset and magnitude of the individual immune response determine the intensity of virus inhibition and the timing of virus elimination from serum.
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immunogenicity in mice and rabbits of dna vaccines expressing Woodchuck Hepatitis virus antigens
Vaccine, 2008Co-Authors: Alain Luxembourg, Bud C. Tennant, Ken Wills, Robert M Bernard, Drew Hannaman, Stephan Menne, Paul J CoteAbstract:Abstract The licensed vaccine against Hepatitis B virus (HBV) is an effective means to prevent infection, but is not an effective therapeutic strategy to treat established chronic infections when used alone. In an animal model of chronic HBV infection (the Woodchuck experimentally infected with Woodchuck Hepatitis virus (WHV)), the combination of conventional vaccine and potent antiviral drugs has shown promise as a potential therapeutic intervention. This approach might be improved further through the application of newer vaccine technologies. In the present study, we evaluated electroporation (EP)-based intramuscular (i.m.) delivery of a codon-optimized DNA vaccine for the WHV surface antigen (WHsAg) in mice and rabbits. In mice, this immunization procedure compared favorably to vaccination by i.m. injection of the DNA vaccine or i.m. administration of a recombinant WHsAg–alum vaccine, exhibiting characteristics expected to be beneficial for a therapeutic vaccine strategy. These included dose efficiency, consistency, vigorous induction of antibody responses to WHsAg, as well as a Th1 bias. Following scale-up to rabbits, a species that approximates the size of the Woodchuck, the EP dosing regimen was markedly more effective than conventional i.m. injection of the DNA vaccine. Taken together, these results provide the foundation for studies of EP-based DNA immunization in the Woodchuck in order to further assess its potential as an immunotherapeutic approach for treatment of chronic HBV infection in humans.
Taiki Higashimoto - One of the best experts on this subject based on the ideXlab platform.
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the Woodchuck Hepatitis virus post transcriptional regulatory element reduces readthrough transcription from retroviral vectors
Gene Therapy, 2007Co-Authors: Taiki Higashimoto, Fabrizia Urbinati, Ajay Perumbeti, A Zarzuela, Lung Ji Chang, Donald B Kohn, G Jiang, Punam MalikAbstract:The Woodchuck Hepatitis virus post-transcriptional regulatory element reduces readthrough transcription from retroviral vectors
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the Woodchuck Hepatitis virus post transcriptional regulatory element reduces readthrough transcription from retroviral vectors
Gene Therapy, 2007Co-Authors: Taiki Higashimoto, Fabrizia Urbinati, Ajay Perumbeti, A Zarzuela, Lung Ji Chang, Donald B Kohn, G Jiang, Punam MalikAbstract:The Woodchuck Hepatitis virus post-transcriptional regulatory element (WPRE) increases transgene expression from a variety of viral vectors, although the precise mechanism is not known. WPRE is most effective when placed downstream of the transgene, proximal to the polyadenylation signal. We hypothesized that WPRE likely reduces viral mRNA readthrough transcription by improving transcript termination, which in turn would increase viral titers and expression. Using a Cre-lox-mediated plasmid-based assay, we found significant readthrough transcription from gamma-retroviral vector (RV) long terminal repeat (wt RV-LTR) and RV LTR with a self-inactivating deletion (SIN RV-LTR). WPRE, when placed upstream of the RV LTRs, significantly reduced readthrough transcription. Readthrough, present at much lower levels with the SIN HIV-1 LV-LTR, was also reduced with WPRE. When placed in RV vectors, WPRE increased total RV genomic mRNA; and increased viral titers from transiently transfected 293T cells and stable PG13 producer cells by 7- to 15-fold. The mechanism of increased titers and expression was not due to increased nuclear mRNA export, increased rate of viral transcription or a significant increase in viral mRNA half-life. Our results showed that WPRE improved vector genomic transcript termination to increase titers and expression from RVs.
Punam Malik - One of the best experts on this subject based on the ideXlab platform.
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the Woodchuck Hepatitis virus post transcriptional regulatory element reduces readthrough transcription from retroviral vectors
Gene Therapy, 2007Co-Authors: Taiki Higashimoto, Fabrizia Urbinati, Ajay Perumbeti, A Zarzuela, Lung Ji Chang, Donald B Kohn, G Jiang, Punam MalikAbstract:The Woodchuck Hepatitis virus post-transcriptional regulatory element reduces readthrough transcription from retroviral vectors
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the Woodchuck Hepatitis virus post transcriptional regulatory element reduces readthrough transcription from retroviral vectors
Gene Therapy, 2007Co-Authors: Taiki Higashimoto, Fabrizia Urbinati, Ajay Perumbeti, A Zarzuela, Lung Ji Chang, Donald B Kohn, G Jiang, Punam MalikAbstract:The Woodchuck Hepatitis virus post-transcriptional regulatory element (WPRE) increases transgene expression from a variety of viral vectors, although the precise mechanism is not known. WPRE is most effective when placed downstream of the transgene, proximal to the polyadenylation signal. We hypothesized that WPRE likely reduces viral mRNA readthrough transcription by improving transcript termination, which in turn would increase viral titers and expression. Using a Cre-lox-mediated plasmid-based assay, we found significant readthrough transcription from gamma-retroviral vector (RV) long terminal repeat (wt RV-LTR) and RV LTR with a self-inactivating deletion (SIN RV-LTR). WPRE, when placed upstream of the RV LTRs, significantly reduced readthrough transcription. Readthrough, present at much lower levels with the SIN HIV-1 LV-LTR, was also reduced with WPRE. When placed in RV vectors, WPRE increased total RV genomic mRNA; and increased viral titers from transiently transfected 293T cells and stable PG13 producer cells by 7- to 15-fold. The mechanism of increased titers and expression was not due to increased nuclear mRNA export, increased rate of viral transcription or a significant increase in viral mRNA half-life. Our results showed that WPRE improved vector genomic transcript termination to increase titers and expression from RVs.
John L Gerin - One of the best experts on this subject based on the ideXlab platform.
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rapid immunity to vaccination with Woodchuck Hepatitis virus surface antigen using cationic liposome dna complexes as adjuvant
Journal of Medical Virology, 2009Co-Authors: Paul J Cote, Bud C. Tennant, John L Gerin, Scott D Butler, Andrea L George, Jeffery Fairman, Stephan MenneAbstract:Complexes of cationic liposomes and non-coding DNA (CLDC) have shown promise as vaccine adjuvant. Using the Woodchuck animal model of Hepatitis B virus (HBV) infection, the immunogenic effects of CLDC were evaluated following vaccination with three doses of Woodchuck Hepatitis virus surface antigen (WHsAg) adjuvanted with either CLDC or conventional alum and administered intramuscularly (im) or subcutaneously (sc). IM vaccination with WHsAg and CLDC elicited antibodies earlier, in more Woodchucks, and with higher titers than WHsAg and alum. After two vaccine doses, antibody titers were higher following im than sc administration. Woodchucks administered two vaccine doses sc received the third vaccine dose im, and antibody responses reached titers comparable to those elicited by im administration. Following the second vaccine dose, im vaccination with WHsAg and CLDC induced T cell responses to WHsAg and selected WHs peptides and expression of the leukocyte surface marker CD8 and of the Th1 cytokines interferon-gamma and tumor necrosis factor alpha in Woodchucks. T cell responses and CD8/cytokine expression were diminished in Woodchucks from the other groups suggesting that this vaccine regimen induced a skew toward Th1 immune responses. The present study in Woodchucks demonstrates that CLDC-adjuvanted WHsAg vaccine administered im resulted in a more rapid induction of humoral and cellular immune responses compared to conventional, alum-adjuvanted WHsAg vaccine. While less rapid, the immune responses following sc administration can prime the im immune responses. This adjuvant activity of CLDC over alum may be beneficial for therapeutic vaccination in chronic HBV infection. J. Med. Virol. 81:1760–1772, 2009. © 2009 Wiley-Liss, Inc.
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antiviral effect of orally administered β d 2 aminopurine dioxolane in Woodchucks with chronic Woodchuck Hepatitis virus infection
Antimicrobial Agents and Chemotherapy, 2007Co-Authors: Stephan Menne, Paul J Cote, John L Gerin, Scott D Butler, Andrea L George, Ghazia Asif, Jannan Narayanasamy, Selwyn J Hurwitz, Raymond F Schinazi, Bud C. TennantAbstract:(−)-β-d-2-Aminopurine dioxolane (APD) is a nucleoside prodrug that is efficiently converted to 9-(β-d-1,3-dioxolan-4-yl)guanine (DXG). DXG has antiviral activity in vitro against Hepatitis B virus (HBV) but limited aqueous solubility, making it difficult to administer orally to HBV-infected individuals. APD is more water soluble than DXG and represents a promising prodrug for the delivery of DXG. A placebo-controlled, dose-ranging efficacy and pharmacokinetic study was conducted with Woodchucks that were chronically infected with Woodchuck Hepatitis virus (WHV). APD was efficiently converted to DXG after oral and intravenous administrations of APD, with serum concentrations of DXG being higher following oral administration than following intravenous administration, suggestive of a considerable first-pass intestinal and/or hepatic metabolism. APD administered orally at 1, 3, 10, and 30 mg/kg of body weight per day for 4 weeks produced a dose-dependent antiviral response. Doses of 3 and 10 mg/kg/day reduced serum WHV viremia by 0.4 and 0.7 log 10 copies/ml, respectively. The 30-mg/kg/day dose resulted in a more pronounced, statistically significant decline in serum WHV viremia of 1.9 log 10 copies/ml and was associated with a 1.5-fold reduction in hepatic WHV DNA. Individual Woodchucks within the highest APD dose group that had declines in serum WHV surface antigen levels, WHV viremia, and hepatic WHV DNA also had reductions in hepatic WHV RNA. There was a prompt recrudescence of WHV viremia following drug withdrawal. Therefore, oral administration of APD for 4 weeks was safe in the Woodchuck model of chronic HBV infection, and the effect on serum WHV viremia was dose dependent.
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immunosuppression reactivates viral replication long after resolution of Woodchuck Hepatitis virus infection
Hepatology, 2007Co-Authors: Stephan Menne, Paul J Cote, John L Gerin, Illia A Toshkov, Scott D Butler, Bud C. TennantAbstract:Resolution of Hepatitis B virus (HBV) infection is characterized by coordinated humoral and cellular immune responses. Immunity is durable over decades, protecting the host from reinfection and potential activation of residual HBV. Woodchucks infected at birth with Woodchuck Hepatitis virus (WHV) cleared viremia and developed antibodies to surface antigen (anti-WHs). Woodchucks became seronegative for anti-WHs 3-6 years later, but in some, WHV DNA was detected in serum, liver, and/or peripheral blood mononuclear cells (PBMCs). Those with WHV DNA had increased in vitro cellular immune responses to viral antigens, CD4 and CD8 markers, and Th1-type cytokines, suggesting active WHV-specific T lymphocytes. Immunosuppression for 12 weeks using cyclosporine A in such Woodchucks resulted in transient reactivation of WHV replication. Serum of 1 Woodchuck that became positive for WHV DNA during immunosuppression was inoculated into WHV-susceptible Woodchucks, and a productive infection was demonstrated. The results indicate that after infection durable cellular immunity to WHV is essential for the long-term control of viral replication and is probably maintained by continuous priming from residual virus. Conclusion: These experimental observations demonstrate the potential of immunosuppression to reactivate HBV after resolution of infection. (HEPATOLOGY 2007;45:614–622.)
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antiviral effect of oral administration of tenofovir disoproxil fumarate in Woodchucks with chronic Woodchuck Hepatitis virus infection
Antimicrobial Agents and Chemotherapy, 2005Co-Authors: Stephan Menne, Brent E Korba, Paul J Cote, John L Gerin, Ilia A Tochkov, Scott D Butler, Andrea L George, William E Delaney, Shelly Xiong, Bud C. TennantAbstract:Tenofovir disoproxil fumarate (TDF) is a nucleotide analogue approved for treatment of human immunodeficiency virus (HIV) infection. TDF also has been shown in vitro to inhibit replication of wild-type Hepatitis B virus (HBV) and lamivudine-resistant HBV mutants and to inhibit lamivudine-resistant HBV in patients and HBV in patients coinfected with the HIV. Data on the in vivo efficacy of TDF against wild-type virus in non-HIV-coinfected or lamivudine-naive chronic HBV-infected patients are lacking in the published literature. The antiviral effect of oral administration of TDF against chronic Woodchuck Hepatitis virus (WHV) infection, an established and predictive animal model for antiviral therapy, was evaluated in a placebo-controlled, dose-ranging study (doses, 0.5 to 15.0 mg/kg of body weight/day). Four weeks of once-daily treatment with TDF doses of 0.5, 1.5, or 5.0 mg/kg/day reduced serum WHV viremia significantly (0.2 to 1.5 log reduction from pretreatment level). No effects on the levels of anti-WHV core and anti-WHV surface antibodies in serum or on the concentrations of WHV RNA or WHV antigens in the liver of treated Woodchucks were observed. Individual TDF-treated Woodchucks demonstrated transient declines in WHV surface antigen serum antigenemia and, characteristically, these Woodchucks also had transient declines in serum WHV viremia, intrahepatic WHV replication, and hepatic expression of WHV antigens. No evidence of toxicity was observed in any of the TDF-treated Woodchucks. Following drug withdrawal there was prompt recrudescence of WHV viremia to pretreatment levels. It was concluded that oral administration of TDF for 4 weeks was safe and effective in the Woodchuck model of chronic HBV infection.
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clevudine therapy with vaccine inhibits progression of chronic Hepatitis and delays onset of hepatocellular carcinoma in chronic Woodchuck Hepatitis virus infection
Antiviral Therapy, 2004Co-Authors: Brent E Korba, Bud C. Tennant, Frances V Wells, Paul J Cote, Illia A Toshkov, Betty H Baldwin, Stephan Menne, John L GerinAbstract:: We examined a rational approach to therapy of chronic Hepatitis B virus (HBV) infection that utilized the reduction of viral load combined with appropriately timed immune modulation/stimulation. In a placebo-controlled study, chronic Woodchuck Hepatitis virus (WHV) carrier Woodchucks received clevudine (L-FMAU), previously shown to have especially potent and sustained antiviral activity in Woodchucks, for 32 weeks followed by WHV surface antigen (WHsAg) alum-adjuvanted vaccine at 32, 36, 40 and 48 weeks. Clevudine induced significant reductions in viraemia, surface antigenaemia, hepatic WHV nucleic acids, and hepatic core and surface antigens. Viral replication markers remained markedly suppressed in 75% of the clevudine-treated Woodchucks following drug withdrawal, but remained at high levels in the vaccine monotherapy and placebo groups. Combination drug and vaccine therapy had benefits based on sustained reduction of viraemia, antigenaemia, and hepatic WHV DNA and RNA; inhibition of progression of chronic Hepatitis; reduced frequency of chronic liver injury; and delayed onset of hepatocellular carcinoma (HCC). Combination therapy contributed to prevention of HCC in up to 38% of treated carriers, although the growth rate of established HCC was not affected. This study demonstrates enhanced benefits of combination chemo-immunotherapy against viral load and disease progression in chronic hepadnaviral infection, and provides a platform for further development of such treatment regimens.
