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Thomas P Monath – One of the best experts on this subject based on the ideXlab platform.

  • Comparison of the safety and immunogenicity of ACAM1000, ACAM2000 and Dryvax® in healthy vaccinia-naive adults.
    Vaccine, 2008
    Co-Authors: Sharon E. Frey, Jeffrey S. Kennedy, Frances K. Newman, Francis A. Ennis, Getahun Abate, Daniel F. Hoft, Thomas P Monath
    Abstract:

    Abstract Currently, more than half of the world’s population has no immunity against smallpox variola major virus. This phase I double-blind, randomized trial was conducted to compare the safety and immunogenicity of two clonally derived, cell-culture manufactured vaccinia strains, ACAM1000 and ACAM2000, to the parent vaccine, Dryvax®. Thirty vaccinia-naive subjects were enrolled into each of three groups and vaccines were administered percutaneously using a bifurcated needle at a dose of 1.0 × 108 PFU/mL. All subjects had a primary skin reaction indicating a successful vaccination. The adverse events, 4-fold neutralizing antibody rise and T cell immune responses were similar between the groups.

  • Clonal vaccinia virus grown in cell culture fully protects monkeys from lethal monkeypox challenge
    Vaccine, 2007
    Co-Authors: Kathleen A. Marriott, Christopher V. Parkinson, Samantha I. Morefield, Robert Davenport, Richard J. Nichols, Thomas P Monath
    Abstract:

    The potential use of smallpox as an agent of bioterrorism has renewed interest in the development of a modern vaccine capable of replacing the standard Dryvax® vaccine. Vaccinia virus (ACAM2000), clonally isolated from Dryvax® and manufactured in cell culture, was tested for immunogenicity and protective activity in a non-human primate model. Cynomolgus monkeys vaccinated with ACAM2000, Dryvax®, or ACAM2000 diluent (control) were challenged 2 months post-vaccination with a lethal, intravenous dose of monkeypox virus. ACAM2000 proved immunogenic and efficacious in protecting against lethal monkeypox challenge, as evident from a lack of post-challenge viral replication, and the absence of any significant clinical signs attributable to monkeypox infection. This protection correlated (with) neutralizing antibody titers equivalent to those generated in the Dryvax® group post-vaccination, as well as a similar significant increase in the presence of neutralizing antibodies post-challenge. Control animals showed no signs of vaccine-induced seroconversion, displayed post-challenge tissue-associated viral replication and viremia, and developed severe monkeypox-specific clinical symptoms. The protective efficacy of ACAM2000 was found to be equivalent to the currently approved vaccine, Dryvax®.

  • a novel cell culture derived smallpox vaccine in vaccinia naive adults
    Vaccine, 2005
    Co-Authors: Andrew W Artenstein, Casey Johnson, Thomas C Marbury, Dennis Morrison, Paul S Blum, Tracy Kemp, Richard A Nichols, John P Balser, Michelle Currie, Thomas P Monath
    Abstract:

    Abstract Despite the eradication of smallpox as a naturally occurring disease, concern persists over its potential use as a bioterrorist agent. The development of a new-generation smallpox vaccine represents an important contribution to a cogent biodefense strategy. We conducted a phase 2 randomized, double-blind, controlled trial at four sites in the United States to determine whether a clonal smallpox vaccine manufactured in cell culture, ACAM2000, is equivalent to the standard calf-lymph vaccine, Dryvax ® , in terms of cutaneous response rate, antibody responses and safety. Subjects received either Dryvax ® or one of four dose levels of ACAM2000 administered percutaneously using a bifurcated needle. All subjects in the highest ACAM2000 dose group and the Dryvax ® group experienced a successful vaccination. Dilution doses of ACAM2000 were associated with success rates below the 90% threshold established for efficacy. There were no differences in the proportion of subjects who developed neutralizing antibody: 94% in the highest ACAM2000 dose group (95% CI, 84–99) and 96% in the Dryvax ® group (95% CI, 86–100). No significant differences were seen between the effective ACAM2000 and Dryvax ® groups regarding the occurrence of adverse events. One subject who received ACAM2000 developed myopericarditis. In healthy, primary vaccines ACAM2000 has a similar vaccination success rate, antibody response, and safety profile to Dryvax.

Inger K. Damon – One of the best experts on this subject based on the ideXlab platform.

  • genomic analysis phenotype and virulence of the historical brazilian smallpox vaccine strain ioc implications for the origins and evolutionary relationships of vaccinia virus
    Journal of Virology, 2015
    Co-Authors: Maria Luiza G Medaglia, Inger K. Damon, Nissin Moussatche, Andreas Nitsche, Pjotr Wojtek Dabrowski, Carolina Lucas, Luciana Barros De Arruda, Clarissa R Damaso
    Abstract:

    ABSTRACT Smallpox was declared eradicated in 1980 after an intensive vaccination program using different strains of vaccinia virus (VACV; Poxviridae). VACV strain IOC (VACV-IOC) was the seed strain of the smallpox vaccine manufactured by the major vaccine producer in Brazil during the smallpox eradication program. However, little is known about the biological and immunological features as well as the phylogenetic relationships of this first-generation vaccine. In this work, we present a comprehensive characterization of two clones of VACV-IOC. Both clones had low virulence in infected mice and induced a protective immune response against a lethal infection comparable to the response of the licensed vaccine ACAM2000 and the parental strain VACV-IOC. Full-genome sequencing revealed the presence of several fragmented virulence genes that probably are nonfunctional, e.g., F1L, B13R, C10L, K3L, and C3L. Most notably, phylogenetic inference supported by the structural analysis of the genome ends provides evidence of a novel, independent cluster in VACV phylogeny formed by VACV-IOC, the Brazilian field strains Cantagalo (CTGV) and Serro 2 viruses, and horsepox virus, a VACV-like virus supposedly related to an ancestor of the VACV lineage. Our data strongly support the hypothesis that CTGV-like viruses represent feral VACV that evolved in parallel with VACV-IOC after splitting from a most recent common ancestor, probably an ancient smallpox vaccine strain related to horsepox virus. Our data, together with an interesting historical investigation, revisit the origins of VACV and propose new evolutionary relationships between ancient and extant VACV strains, mainly horsepox virus, VACV-IOC/CTGV-like viruses, and Dryvax strain. IMPORTANCE First-generation vaccines used to eradicate smallpox had rates of adverse effects that are not acceptable by current health care standards. Moreover, these vaccines are genetically heterogeneous and consist of a pool of quasispecies of VACV. Therefore, the search for new-generation smallpox vaccines that combine low pathogenicity, immune protection, and genetic homogeneity is extremely important. In addition, the phylogenetic relationships and origins of VACV strains are quite nebulous. We show the characterization of two clones of VACV-IOC, a unique smallpox vaccine strain that contributed to smallpox eradication in Brazil. The immunogenicity and reduced virulence make the IOC clones good options for alternative second-generation smallpox vaccines. More importantly, this study reveals the phylogenetic relationship between VACV-IOC, feral VACV established in nature, and the ancestor-like horsepox virus. Our data expand the discussion on the origins and evolutionary connections of VACV lineages.

  • Clinical guidance for smallpox vaccine use in a postevent vaccination program.
    MMWR. Recommendations and reports : Morbidity and mortality weekly report. Recommendations and reports, 2015
    Co-Authors: Brett W. Petersen, Inger K. Damon, Carol A Pertowski, Dana Meaney-delman, Julie T. Guarnizo, Richard H. Beigi, Kathryn M. Edwards, Margaret C. Fisher, Sharon E. Frey, Ruth Lynfield
    Abstract:

    This report outlines recommendations for the clinical use of the three smallpox vaccines stored in the U.S. Strategic National Stockpile for persons who are exposed to smallpox virus or at high risk for smallpox infection during a postevent vaccination program following an intentional or accidental release of the virus. No absolute contraindications exist for smallpox vaccination in a postevent setting. However, several relative contraindications exist among persons with certain medical conditions. CDC recommendations for smallpox vaccine use were developed in consideration of the risk for smallpox infection, risk for an adverse event following vaccination, and benefit from vaccination. Smallpox vaccines are made from live vaccinia viruses that protect against smallpox disease. They do not contain variola virus, the causative agent of smallpox. The three smallpox vaccines stockpiled are ACAM2000, Aventis Pasteur Smallpox Vaccine (APSV), and Imvamune. Surveillance and containment activities including vaccination with replication-competent smallpox vaccine (i.e., vaccine viruses capable of replicating in mammalian cells such as ACAM2000 and APSV) will be the primary response strategy for achieving epidemic control. Persons exposed to smallpox virus are at high risk for developing and transmitting smallpox and should be vaccinated with a replication-competent smallpox vaccine unless severely immunodeficient. Because of a high likelihood of a poor immune response and an increased risk for adverse events, smallpox vaccination should be avoided in persons with severe immunodeficiency who are not expected to benefit from vaccine, including bone marrow transplant recipients within 4 months of transplantation, persons infected with HIV with CD4 cell counts

  • clinical guidance for smallpox vaccine use in a postevent vaccination program
    MMWR. Recommendations and reports : Morbidity and mortality weekly report. Recommendations and reports Centers for Disease Control, 2015
    Co-Authors: Brett W. Petersen, Inger K. Damon, Carol A Pertowski, Julie T. Guarnizo, Richard H. Beigi, Kathryn M. Edwards, Margaret C. Fisher, Sharon E. Frey, Dana Meaneydelman, Ruth Lynfield
    Abstract:

    This report outlines recommendations for the clinical use of the three smallpox vaccines stored in the U.S. Strategic National Stockpile for persons who are exposed to smallpox virus or at high risk for smallpox infection during a postevent vaccination program following an intentional or accidental release of the virus. No absolute contraindications exist for smallpox vaccination in a postevent setting. However, several relative contraindications exist among persons with certain medical conditions. CDC recommendations for smallpox vaccine use were developed in consideration of the risk for smallpox infection, risk for an adverse event following vaccination, and benefit from vaccination. Smallpox vaccines are made from live vaccinia viruses that protect against smallpox disease. They do not contain variola virus, the causative agent of smallpox. The three smallpox vaccines stockpiled are ACAM2000, Aventis Pasteur Smallpox Vaccine (APSV), and Imvamune. Surveillance and containment activities including vaccination with replication-competent smallpox vaccine (i.e., vaccine viruses capable of replicating in mammalian cells such as ACAM2000 and APSV) will be the primary response strategy for achieving epidemic control. Persons exposed to smallpox virus are at high risk for developing and transmitting smallpox and should be vaccinated with a replication-competent smallpox vaccine unless severely immunodeficient. Because of a high likelihood of a poor immune response and an increased risk for adverse events, smallpox vaccination should be avoided in persons with severe immunodeficiency who are not expected to benefit from vaccine, including bone marrow transplant recipients within 4 months of transplantation, persons infected with HIV with CD4 cell counts <50 cells/mm3, and persons with severe combined immunodeficiency, complete DiGeorge syndrome, and other severely immunocompromised states requiring isolation. If antivirals are not immediately available, it is reasonable to consider the use of Imvamune in the setting of a smallpox virus exposure in persons with severe immunodeficiency. Persons without a known smallpox virus exposure might still be at high risk for developing smallpox infection depending on the magnitude of the outbreak and the effectiveness of the public health response. Such persons will be defined by public health authorities and should be screened for relative contraindications to smallpox vaccination. Relative contraindications include atopic dermatitis (eczema), HIV infection (CD4 cell counts of 50-199 cells/mm3), other immunocompromised states, and vaccine or vaccine-component allergies. Persons with relative contraindications should be vaccinated with Imvamune when available and authorized for use by the Food and Drug Administration. These recommendations will be updated as new data on smallpox vaccines become available and further clinical guidance for other medical countermeasures including antivirals is developed.

Douglas W. Grosenbach – One of the best experts on this subject based on the ideXlab platform.

  • Co-administration of tecovirimat and ACAM2000™ in non-human primates: Effect of tecovirimat treatment on ACAM2000 immunogenicity and efficacy versus lethal monkeypox virus challenge.
    Vaccine, 2019
    Co-Authors: Andrew T. Russo, Aklile Berhanu, Douglas W. Grosenbach, Peter Silvera, Catherine B. Bigger, Jon Prigge, Dennis E. Hruby
    Abstract:

    Naturally occurring smallpox has been eradicated but research stocks of variola virus (VARV), the causative agent of smallpox, still exist in secure laboratories. Clandestine stores of the virus or resurrection of VARV via synthetic biology are possible and have led to concerns that VARV could be used as a biological weapon. The US government has prepared for such an event by stockpiling smallpox vaccines and TPOXX®, SIGA Technologies’ smallpox antiviral drug. While vaccination is effective as a pre-exposure propprophylaxis, protection is limited when administered following exposure. Safety concerns preclude general use of the vaccine unless there is a smallpox outbreak. TPOXX is approved by the FDA for use after confirmed diagnosis of smallpox disease. Tecovirimat, the active pharmaceutical ingredient in TPOXX, targets a highly conserved orthopoxviral protein, inhibiting long-range dissemination of virus. Although indications for use of the vaccine and TPOXX do not overlap, concomitant use is possible, especially if the TPOXX indication is expanded to include post-exposure propprophylaxis. It is therefore important to understand how vaccine and TPOXX may interact. In studies presented here, monkeys were vaccinated with the ACAM2000TM live attenuated smallpox vaccine and concomitantly treated with tecovirimat or placebo. Immune responses to the vaccine and protective efficacy versus a lethal monkeypox virus (MPXV) challenge were evaluated. In two studies, primary and anamnestic humoral immune responses were similar regardless of tecovirimat treatment while the third study showed reduction in vaccine elicited humoral immuimmunity. Following lethal MPXV challenge, all (12 of 12) vaccinated/placebo treated animals survived, and 12 of 13 vaccinated/tecovirimat treated animals survived. Clinical signs of disease were elevated in tecovirimat treated animals compared to placebo treated animals. This suggests that TPOXX may affect the immunogenicity of ACAM2000 if administered concomitantly. These studies may inform on how vaccine and TPOXX are used during a smallpox outbreak.

  • Treatment with the smallpox antiviral tecovirimat (ST-246) alone or in combination with ACAM2000 vaccination is effective as a postsymptomatic therapy for monkeypox virus infection.
    Antimicrobial agents and chemotherapy, 2015
    Co-Authors: Aklile Berhanu, Dennis E. Hruby, Jonathan T. Prigge, Peter Silvera, Kady M. Honeychurch, Douglas W. Grosenbach
    Abstract:

    ABSTRACT The therapeutic efficacies of smallpox vaccine ACAM2000 and antiviral tecovirimat given alone or in combination starting on day 3 postinfection were compared in a cynomolgus macaque model of lethal monkeypox virus infection. Postexposure administration of ACAM2000 alone did not provide any protection against severe monkeypox disease or mortality. In contrast, postexposure treatment with tecovirimat alone or in combination with ACAM2000 provided full protection. Additionally, tecovirimat treatment delayed until day 4, 5, or 6 postinfection was 83% (days 4 and 5) or 50% (day 6) effective.

  • impact of st 246 on ACAM2000 smallpox vaccine reactogenicity immunogenicity and protective efficacy in immunodeficient mice
    Vaccine, 2010
    Co-Authors: Aklile Berhanu, David S. King, Stacie Mosier, Robert Jordan, Kevin F. Jones, Dennis E. Hruby, Douglas W. Grosenbach
    Abstract:

    Abstract Although a highly effective vaccine against smallpox, vaccinia virus (VV) is not without adverse events, some of which can be life-threatening, particularly in immunocompromised individuals. We have recently demonstrated that the immunogenicity and protective efficacy of Dryvax® in immunocompetent mice is preserved even when co-administered with ST-246, an orally bioavailable small-molecule inhibitor of orthopoxvirus egress and dissemination. In addition, ST-246 markedly reduced the reactogenicity of the smallpox vaccine ACAM2000 and the highly neurovirulent VV strain Western Reserve (VV-WR). Here, we evaluated the impact of ST-246 co-administration on ACAM2000 reactogenicity, immunogenicity, and protective efficacy in seven murine models of varying degrees of humoral and cellular immunodeficiency: BALB/c and B-cell deficient (JH-KO) mice depleted of CD4+ or CD8+ or both subsets of T cells. We observed that ST-246 reduced vaccine lesion severity and time to complete resolution in all of the immunodeficient models examined, except in those lacking both CD4+ and CD8+ T cells. Although VV-specific humoral responses were moderately reduced by ST-246 treatment, cellular responses were generally comparable or slightly enhanced at both 1 and 6 months post-vaccination. Most importantly, in those models in which vaccination given alone conferred protection against lethal VV challenge, similar levels of protection were observed at both time points when vaccination was given with ST-246. These data suggest that, with the exception of individuals with irreversible, combined CD4+ and CD8+ T-cell deficiency, ST-246 co-administered at the time of vaccination may help reduce vaccine reactogenicity—even in those lacking humoral immuimmunity—without impeding the induction of protective immunity.

Mehmet O. Killinc – One of the best experts on this subject based on the ideXlab platform.

  • First-in-human study of TK-positive oncolytic vaccinia virus delivered by adipose stromal vascular fraction cells
    Journal of translational medicine, 2019
    Co-Authors: Boris Minev, Elliot B Lander, John Feller, Mark Berman, Bernadette Greenwood, Ivelina Minev, Antonio F. Santidrian, Duong Nguyen, Dobrin Draganov, Mehmet O. Killinc
    Abstract:

    ACAM2000, a thymidine kinase (TK)-positive strain of vaccinia virus, is the current smallpox vaccine in the US. Preclinical testing demonstrated potent oncolytic activity of ACAM2000 against several tumor types. This Phase I clinical trial of ACAM2000 delivered by autologous adipose stromal vascular fraction (SVF) cells was conducted to determine the safety and feasibility of such a treatment in patients with advanced solid tumors or acute myeloid leukemia (AML). Twenty-four patients with solid tumors and two patients with AML participated in this open-label, non-randomized dose-escalation trial. All patients were treated with SVF derived from autologous fat and incubated for 15 min to 1 h with ACAM2000 before application. Six patients received systemic intravenous application only, one patient received intra-tumoral application only, 15 patients received combination intravenous with intra-tumoral deployment, 3 patients received intravenous and intra-peritoneal injection and 1 patient received intravenous, intra-tumoral and intra-peritoneal injections. Safety at each dose level of ACAM2000 (1.4 × 106 plaque-forming units (PFU) to 1.8 × 107 PFU) was evaluated. Blood samples for PK assessments, flow cytometry and cytokine analysis were collected at baseline and 1 min, 1 h, 1 day, 1 week, 1 month, 3 months and 6 months following treatment. No serious toxicities (> grade 2) were reported. Seven patients reported an adverse event (AE) in this study: self-limiting skin rashes, lasting 7 to 18 days—an expected adverse reaction to ACAM2000. No AEs leading to study discontinuation were reported. Viral DNA was detected in all patients’ blood samples immediately following treatment. Interestingly, in 8 patients viral DNA disappeared 1 day and re-appeared 1 week post treatment, suggesting active viral replication at tumor sites, and correlating with longer survival of these patients. No major increase in cytokine levels or correlation between cytokine levels and skin rashes was noted. We were able to assess some initial efficacy signals, especially when the ACAM2000/SVF treatment was combined with checkpoint inhibition. Treatment with ACAM2000/SVF in patients with advanced solid tumors or AML is safe and well tolerated, and several patients had signals of an anticancer effect. These promising initial clinical results merit further investigation of therapeutic utility. Trial registration Retrospectively registered (ISRCTN#10201650) on October 22, 2018.

  • First-in-human study of TK-positive oncolytic vaccinia virus delivered by adipose stromal vascular fraction cells
    Journal of Translational Medicine, 2019
    Co-Authors: Boris Minev, Mark Berman, Ivelina Minev, Antonio F. Santidrian, Duong Nguyen, Dobrin Draganov, Elliot Lander, John F. Feller, Bernadette M. Greenwood, Mehmet O. Killinc
    Abstract:

    Background ACAM2000, a thymidine kinase (TK)-positive strain of vaccinia virus, is the current smallpox vaccine in the US. Preclinical testing demonstrated potent oncolytic activity of ACAM2000 against several tumor types. This Phase I clinical trial of ACAM2000 delivered by autologous adipose stromal vascular fraction (SVF) cells was conducted to determine the safety and feasibility of such a treatment in patients with advanced solid tumors or acute myeloid leukemia (AML). Methods Twenty-four patients with solid tumors and two patients with AML participated in this open-label, non-randomized dose-escalation trial. All patients were treated with SVF derived from autologous fat and incubated for 15 min to 1 h with ACAM2000 before application. Six patients received systemic intravenous application only, one patient received intra-tumoral application only, 15 patients received combination intravenous with intra-tumoral deployment, 3 patients received intravenous and intra-peritoneal injection and 1 patient received intravenous, intra-tumoral and intra-peritoneal injections. Safety at each dose level of ACAM2000 (1.4 × 10^6 plaque-forming units (PFU) to 1.8 × 10^7 PFU) was evaluated. Blood samples for PK assessments, flow cytometry and cytokine analysis were collected at baseline and 1 min, 1 h, 1 day, 1 week, 1 month, 3 months and 6 months following treatment. Results No serious toxicities (> grade 2) were reported. Seven patients reported an adverse event (AE) in this study: self-limiting skin rashes, lasting 7 to 18 days—an expected adverse reaction to ACAM2000. No AEs leading to study discontinuation were reported. Viral DNA was detected in all patients’ blood samples immediately following treatment. Interestingly, in 8 patients viral DNA disappeared 1 day and re-appeared 1 week post treatment, suggesting active viral replication at tumor sites, and correlating with longer survival of these patients. No major increase in cytokine levels or correlation between cytokine levels and skin rashes was noted. We were able to assess some initial efficacy signals, especially when the ACAM2000/SVF treatment was combined with checkpoint inhibition. Conclusions Treatment with ACAM2000/SVF in patients with advanced solid tumors or AML is safe and well tolerated, and several patients had signals of an anticancer effect. These promising initial clinical results merit further investigation of therapeutic utility. Trial registration Retrospectively registered (ISRCTN#10201650) on October 22, 2018.

Keith M Howard – One of the best experts on this subject based on the ideXlab platform.

  • vero cell platform in vaccine production moving towards cell culture based viral vaccines
    Expert Review of Vaccines, 2009
    Co-Authors: Noel P Barrett, Wolfgang Mundt, Otfried Kistner, Keith M Howard
    Abstract:

    The development of cell culture systems for virus propagation has led to major advances in virus vaccvaccine development. Primary and diploid cell culture systems are now being replaced by the use of continuous cell lines (CCLs). These substrates are gaining increasing acceptance from regulatory authorities as improved screening technologies remove fears regarding their potential oncogenic properties. The Vero cell line is the most widely accepted CCL by regulatory authorities and has been used for over 30 years for the production of polio and rabies virus vaccines. The recent licensure of a Vero cell-derived live virus vaccine (ACAM2000, smallpox vaccine) has coincided with an explosion in the development of a range of new viral vaccines, ranging from live-attenuated pediatric vaccines against rotavirus infections to inactivated whole-virus vaccines against H5N1 pandemic influenza. These developments have illustrated the value of this cell culture platform in the rapid development of vaccines against a range…

  • vero cell platform in vaccine production moving towards cell culture based viral vaccines
    Expert Review of Vaccines, 2009
    Co-Authors: Noel P Barrett, Wolfgang Mundt, Otfried Kistner, Keith M Howard
    Abstract:

    The development of cell culture systems for virus propagation has led to major advances in virus vaccvaccine development. Primary and diploid cell culture systems are now being replaced by the use of continuous cell lines (CCLs). These substrates are gaining increasing acceptance from regulatory authorities as improved screening technologies remove fears regarding their potential oncogenic properties. The Vero cell line is the most widely accepted CCL by regulatory authorities and has been used for over 30 years for the production of polio and rabies virus vaccines. The recent licensure of a Vero cell-derived live virus vaccine (ACAM2000, smallpox vaccine) has coincided with an explosion in the development of a range of new viral vaccines, ranging from live-attenuated pediatric vaccines against rotavirus infections to inactivated whole-virus vaccines against H5N1 pandemic influenza. These developments have illustrated the value of this cell culture platform in the rapid development of vaccines against a range of virus diseases.