Journal of Infectious The Journal of Infectious Diseases Diseases Advance Access published December 13, 2015
BRIEF REPORT
Stability of a Vesicular Stomatitis Virus–Vectored Ebola Vaccine Marianne Arnemo,1 Sara Sofie Viksmoen Watle,3 Kristin Merete Schoultz,3 Kirsti Vainio,3 Gunnstein Norheim,3 Vasee Moorthy,4 Patricia Fast,4,5 John-Arne Røttingen,2,3,6 and Tor Gjøen1 1 Department of Pharmaceutical Biosciences, School of Pharmacy, and 2Department of Health and Society, University of Oslo, and 3Norwegian Institute of Public Health, Oslo, Norway; 4World Health Organization, Geneva, Switzerland; 5International AIDS Vaccine Initiative, New York, New York; and 6Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
METHODS rVSV-ZEBOV Vaccine
The 2014–2015 outbreak of Ebola virus disease (EVD) in West Africa has accelerated the development and testing of new therapeutic and prophylactic drugs and vaccines to cure or prevent EVD. One of the vaccines undergoing clinical trials is based on vesicular stomatitis virus (VSV) [1]. VSV is a negative-sense, single-stranded RNA virus in the family Rhabdoviridae [2]. The vaccine candidate rVSV-ZEBOV is a live attenuated recombinant virus consisting of the VSV Indiana strain with the gene for the Zaire Kikwit 1995 Ebolavirus (ZEBOV) glycoprotein (ZEBOV-GP) replacing the gene for the VSV glycoprotein [3]. This results in a VSV backbone with the ZEBOV-GP covering the surface of the virus. The rVSV-ZEBOV vaccine induces full protection against EVD in ZEBOV-challenged mice, guinea pigs, and nonhuman primates [4] and also provides effective protection in mice, guinea pigs, and nonhuman primates [5] after ZEBOV exposure. There is also 1 case report of possible postexposure protection in humans [6].
Received 21 August 2015; accepted 2 November 2015. Correspondence: T. Gjøen, Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, PO Box 1068 Blindern, Oslo NO-0316, Norway ([email protected]). The Journal of Infectious Diseases® © The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail [email protected]. DOI: 10.1093/infdis/jiv532
The rVSV-ZEBOV vaccine was developed by the Public Health Agency of Canada, licensed to BioProtection Systems (NewLink Genetics), and sublicensed to Merck, which is responsible for ongoing research and development [3, 7]. The rVSV-ZEBOV vaccine lot tested in this report (lot no. 003 05 13) was manufactured according to good manufacturing practices and used in phase I trials [3, 7]. The vaccine is formulated with 2.5 g/L recombinant human serum albumin and 10 mM Tris pH 7.2 and dispensed in a 1.0-mL single-dose vial, with each vial containing ≥1 × 108 PFU/mL. The Canadian government donated 800 vaccine vials to the World Health Organization, which provided the Norwegian Institute of Public Health with 5 vials in January 2015 for use in stability testing prior to the start of clinical trials in Guinea. Thawing, Dilution, Incubation, and pH Measurements of the Vaccine
The vaccine vials were stored at −70°C until start of testing. Immediately after thawing, designated as time 0 (T0), a sample was collected. The vaccine was then either incubated in the undiluted form or diluted (as described in Supplementary File 1) into 0.9% NaCl (Fresenius Kabi, Bad Homburg, Germany). The vaccine was kept in Eppendorf polypropylene tubes for short-term stability tests and in the original glass vials for long-term tests. Eppendorf polypropylene tubes were used to simulate the dilution conditions relevant for the planned clinical trial. Standard laboratory incubators were used for incubations at 25°C (Thermo BRIEF REPORT
•
JID
•
1
Downloaded from http://jid.oxfordjournals.org/ at KTH Royal Institute of Technology on February 8, 2016
The live attenuated vesicular stomatitis virus–vectored Ebola vaccine rVSV-ZEBOV is currently undergoing clinical trials in West Africa. The vaccine is to be stored at −70°C or less. Since maintaining the cold chain is challenging in rural areas, the rVSV-ZEBOV vaccine’s short-term and long-term stability at different temperatures was examined. Different dilutions were tested since the optimal vaccine dosage had not yet been determined at the start of this experiment. The results demonstrate that the original vaccine formulation was stable for 1 week at 4°C and for 24 hours at 25°C. The stability of the vaccine was compromised by both high temperatures and dilution. Keywords. Ebola; virus; vaccine; VSV; stability.
In phase I trials, volunteers were immunized with single doses ranging from 300 000 to 10 million plaque-forming units (PFU). The vaccine was shown to be safe and immunogenic [3, 7]. The vaccine is currently being tested in phase II and III trials in Guinea (clinical trials registration: PACTR201503001057193), Sierra Leone (PACTR201502001037220), and Liberia (NCT02344407). The recently published interim report of the phase III trial in Guinea demonstrated that the vaccine was 74.7%–100% effective [8]. The rVSV-ZEBOV vaccine requires storage at −70°C or less. Maintaining the cold chain of vaccine delivery is important since damage from accidental heating or freezing can result in potency loss for several vaccines commonly used in national immunization programs [9]. Previous stability studies of recombinant VSV suggest that this virus may be affected by pH, temperature, and protein concentration [10]. Owing to limited stability data for the rVSV-ZEBOV vaccine, it was important to evaluate these parameters before using the vaccine in the field during phase II and III trials. Prior to the start of clinical trials in West Africa, the decision about which dose to use had not been made. Therefore, we tested different vaccine concentrations.
Fisher Scientific, Waltham, Massachusetts) and 40°C (Termaks, Bergen, Norway). A standard consumer refrigerator (Electrolux, Stockholm, Sweden) was used for incubation at 4°C. The pH was measured by a Laquatwin Compact pH meter (Horiba Scientific, Kyoto, Japan). VSV Plaque Assay
The data are descriptively presented in graphs as PFU per milliliter. Averages, standard deviations, numbers of replicates, and P values are specified in Supplementary File 1. The number of PFU did not follow a normal distribution, and statistical testing was therefore performed using log10-transformed values. Statistical testing focused on assessing whether the viral titer in the vaccine was significantly affected by changes in temperature over time. An unpaired 2-tailed t test was performed, comparing the number of PFU per milliliter at every time point tested with the number at T0. A P value of .001; Figure 2B). After 14 days, the viral titer was significantly reduced (P < .001), and after 84 days the viral titer was reduced to approximately 2 × 104 PFU/mL, a reduction of 4 logs (Figure 2B). DISCUSSION
Here we report the short-term and long-term stability of the rVSV-ZEBOV vaccine in both undiluted and diluted form and at different temperatures. The short-term stability tests
BRIEF REPORT
•
JID
•
3
Downloaded from http://jid.oxfordjournals.org/ at KTH Royal Institute of Technology on February 8, 2016
Figure 2. A, The effect of dilution on pH. B, Stability of undiluted live attenuated vesicular stomatitis virus–vectored Ebola vaccine, rVSV-ZEBOV, during storage for 3 months at 4°C in the original vial. Samples were collected at days 0 (T0), 7, 14, 28, 56, and 84. The number of replicates included per time point was as follows: 12 (T0), 17 (day 14), and 18 (days 7, 28, 56, and 84). Long-term stability data originate from 1 experiment (1 vaccine vial). The asterisk indicates a significant difference (P < .001) from the value at T0. Abbreviation: PFU, plaque-forming units.
demonstrated that the vaccine can be stored at 4°C and 25°C for 24 hours at all three tested concentrations (1 × 108 PFU/ mL, 2 × 107 PFU/mL, and 3 × 106 PFU/mL) without significant loss of viral titer (Figure 1A–C). Storage of vaccine at 40°C caused a significant reduction in the vaccine titer at all concentrations tested (Figure 1A–C). These results are in line with stability data from the vaccine producer (Merck Vaccines, personal communication). These short-term stability results are also in agreement with those for a previously studied, non–EVD-relevant recombinant VSV formulation [10], demonstrating that stability decreases when the temperature is increased or the concentration of virus is decreased. The same report also showed that serum had a stabilizing effect on VSV infectivity [10]. Upon dilution, the concentration of serum in the vaccine is reduced, which may contribute to the lower stability of the most diluted form. The effects of temperature on the vaccine stability are in agreement with the stability of other rhabdoviruses (eg, rabies virus) [11, 12]. When diluted with NaCl, the pH of the vaccine decreased toward the level in the diluent (Figure 2A). Previous studies suggest that VSV is more sensitive to acidic conditions than to alkaline conditions [10]. This may be due to pH-sensitive glycoproteins [13]. However, the role of low pH for ZEBOV-GP function has been questioned [14]. The effect of the acidification on the infectivity of the rVSV-ZEBOV vaccine is therefore uncertain but is probably of less concern for the rVSV–ZEBOV-GP virus than for wild-type VSV, which is known to be dependent on low pH [13]. When opened immediately after thawing, the undiluted rVSV-ZEBOV vaccine in its original vial was stable for 1 week in a refrigerator (Figure 2B) but displayed a significant reduction in viral titer after 2 weeks. This result is not aligned with stability data from Merck (Merck Vaccines, personal communication). However, it is important to recognize that these results do not reflect the stability of sealed vials because the vials used in this experiment were opened immediately after thawing and because samples were collected repeatedly from the same vial. Most likely, the stability of vaccine from unopened vials would be better, but owing to the limited number of vaccine vials available to us, this was not possible to test in our laboratory. Although a significant reduction in vaccine concentration was observed after 2 weeks of refrigeration, the vaccine dose may still be immunogenic and protective. This could be investigated by further studies in animal models. In conclusion, the rVSV-ZEBOV vaccine is stable for at least 1 week after thawing, opening, and storage of the vaccine vial in a refrigerator. Undiluted and diluted vaccine maintains its potency for 24 hours at 25°C. Increased temperatures (ie, >25°C) reduce the stability of the vaccine. The rVSV-ZEBOV vaccine tested here has recently demonstrated promising preliminary results in the phase III vaccine trial in Guinea [8], and the dose used for vaccination was 2 × 107 PFU. This report provides timely assessment of the stability of this vaccine, indicates
stability at temperatures associated with refrigerators, and may be useful in the logistical planning for implementation of targeted use of the vaccine in the current and future Ebola outbreaks, once the vaccine is licensed for use. Supplementary Data Supplementary materials are available at http://jid.oxfordjournals.org. Consisting of data provided by the author to benefit the reader, the posted materials are not copyedited and are the sole responsibility of the author, so questions or comments should be addressed to the author.
References 1. Kanapathipillai R, Henao Restrepo AM, Fast P, et al. Ebola vaccine—an urgent international priority. N Engl J Med 2014; 371:2249–51.
4
•
JID
•
BRIEF REPORT
Downloaded from http://jid.oxfordjournals.org/ at KTH Royal Institute of Technology on February 8, 2016
Notes Acknowledgments. We thank the Public Health Agency of Canada, for donation of the vaccine vials to the World Health Organization; Bjørg Dystvold Nilsson, for coordination of the project at the Norwegian Institute of Public Health; Susanne Dudmann, for providing laboratory facilities to perform the work; and Hang Le, Remilyn Ramos-Ocao, and Wenche Holmen, for technical help in laboratory facilities. Financial support. This work was supported by the Norwegian Ministry of Foreign Affairs through the Research Council of Norway (grant 246662). Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
2. Lichty BD, Power AT, Stojdl DF, Bell JC. Vesicular stomatitis virus: re-inventing the bullet. Trends Mol Med 2004; 10:210–6. 3. Regules JA, Beigel JH, Paolino KM, et al. A recombinant vesicular stomatitis virus Ebola vaccine—preliminary report. N Engl J Med 2015; doi:10.1056/ NEJMoa1414216. 4. Marzi A, Feldmann H, Geisbert TW, Falzarano D. Vesicular stomatitis virus-based vaccines for prophylaxis and treatment of filovirus infections. J Bioterror Biodef 2011; pii:2157-2526-S1-004. 5. Feldmann H, Jones SM, Daddario-DiCaprio KM, et al. Effective post-exposure treatment of Ebola infection. PLoS Pathog 2007; 3:e2. 6. Lai L, Davey R, Beck A, et al. Emergency postexposure vaccination with vesicular stomatitis virus–vectored Ebola vaccine after needlestick. JAMA 2015; 313: 1249–55. 7. Agnandji ST, Huttner A, Zinser ME, et al. Phase 1 trials of rVSV Ebola vaccine in Africa and Europe—preliminary report. N Engl J Med 2015; doi:10.1056/ NEJMoa1502924. 8. Henao-Restrepo AM, Longini IM, Egger M, et al. Efficacy and effectiveness of an rVSV-vectored vaccine expressing Ebola surface glycoprotein: interim results from the Guinea ring vaccination cluster-randomised trial. Lancet 2015; 386:857–66. 9. Milstien JB, Galazka AM, Kartoglu UM, Zaffran M. Temperature sensitivity of vaccines. WHO/IVB/06.10. Geneva: World Health Organization, 2006. 10. Zimmer B, Summermatter K, Zimmer G. Stability and inactivation of vesicular stomatitis virus, a prototype rhabdovirus. Vet Microbiol 2013; 162:78–84. 11. Michalski F, Parks NF, Sokol F, Clark HF. Thermal inactivation of rabies and other rhabdoviruses: stabilization by the chelating agent ethylenediaminetetraacetic acid at physiological temperatures. Infect Immun 1976; 14:135–43. 12. Lawson KF, Bachmann P. Stability of attenuated live virus rabies vaccine in baits targeted to wild foxes under operational conditions. Can Vet J 2001; 42:368–74. 13. Mercer J, Schelhaas M, Helenius A. Virus entry by endocytosis. Annu Rev Biochem 2010; 79:803–33. 14. Bär S, Takada A, Kawaoka Y, Alizon M. Detection of cell-cell fusion mediated by Ebola virus glycoproteins. J Virol 2006; 80:2815–22.
BRIEF REPORT
Stability of a Vesicular Stomatitis Virus–Vectored Ebola Vaccine Marianne Arnemo,1 Sara Sofie Viksmoen Watle,3 Kristin Merete Schoultz,3 Kirsti Vainio,3 Gunnstein Norheim,3 Vasee Moorthy,4 Patricia Fast,4,5 John-Arne Røttingen,2,3,6 and Tor Gjøen1 1 Department of Pharmaceutical Biosciences, School of Pharmacy, and 2Department of Health and Society, University of Oslo, and 3Norwegian Institute of Public Health, Oslo, Norway; 4World Health Organization, Geneva, Switzerland; 5International AIDS Vaccine Initiative, New York, New York; and 6Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
METHODS rVSV-ZEBOV Vaccine
The 2014–2015 outbreak of Ebola virus disease (EVD) in West Africa has accelerated the development and testing of new therapeutic and prophylactic drugs and vaccines to cure or prevent EVD. One of the vaccines undergoing clinical trials is based on vesicular stomatitis virus (VSV) [1]. VSV is a negative-sense, single-stranded RNA virus in the family Rhabdoviridae [2]. The vaccine candidate rVSV-ZEBOV is a live attenuated recombinant virus consisting of the VSV Indiana strain with the gene for the Zaire Kikwit 1995 Ebolavirus (ZEBOV) glycoprotein (ZEBOV-GP) replacing the gene for the VSV glycoprotein [3]. This results in a VSV backbone with the ZEBOV-GP covering the surface of the virus. The rVSV-ZEBOV vaccine induces full protection against EVD in ZEBOV-challenged mice, guinea pigs, and nonhuman primates [4] and also provides effective protection in mice, guinea pigs, and nonhuman primates [5] after ZEBOV exposure. There is also 1 case report of possible postexposure protection in humans [6].
Received 21 August 2015; accepted 2 November 2015. Correspondence: T. Gjøen, Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, PO Box 1068 Blindern, Oslo NO-0316, Norway ([email protected]). The Journal of Infectious Diseases® © The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail [email protected]. DOI: 10.1093/infdis/jiv532
The rVSV-ZEBOV vaccine was developed by the Public Health Agency of Canada, licensed to BioProtection Systems (NewLink Genetics), and sublicensed to Merck, which is responsible for ongoing research and development [3, 7]. The rVSV-ZEBOV vaccine lot tested in this report (lot no. 003 05 13) was manufactured according to good manufacturing practices and used in phase I trials [3, 7]. The vaccine is formulated with 2.5 g/L recombinant human serum albumin and 10 mM Tris pH 7.2 and dispensed in a 1.0-mL single-dose vial, with each vial containing ≥1 × 108 PFU/mL. The Canadian government donated 800 vaccine vials to the World Health Organization, which provided the Norwegian Institute of Public Health with 5 vials in January 2015 for use in stability testing prior to the start of clinical trials in Guinea. Thawing, Dilution, Incubation, and pH Measurements of the Vaccine
The vaccine vials were stored at −70°C until start of testing. Immediately after thawing, designated as time 0 (T0), a sample was collected. The vaccine was then either incubated in the undiluted form or diluted (as described in Supplementary File 1) into 0.9% NaCl (Fresenius Kabi, Bad Homburg, Germany). The vaccine was kept in Eppendorf polypropylene tubes for short-term stability tests and in the original glass vials for long-term tests. Eppendorf polypropylene tubes were used to simulate the dilution conditions relevant for the planned clinical trial. Standard laboratory incubators were used for incubations at 25°C (Thermo BRIEF REPORT
•
JID
•
1
Downloaded from http://jid.oxfordjournals.org/ at KTH Royal Institute of Technology on February 8, 2016
The live attenuated vesicular stomatitis virus–vectored Ebola vaccine rVSV-ZEBOV is currently undergoing clinical trials in West Africa. The vaccine is to be stored at −70°C or less. Since maintaining the cold chain is challenging in rural areas, the rVSV-ZEBOV vaccine’s short-term and long-term stability at different temperatures was examined. Different dilutions were tested since the optimal vaccine dosage had not yet been determined at the start of this experiment. The results demonstrate that the original vaccine formulation was stable for 1 week at 4°C and for 24 hours at 25°C. The stability of the vaccine was compromised by both high temperatures and dilution. Keywords. Ebola; virus; vaccine; VSV; stability.
In phase I trials, volunteers were immunized with single doses ranging from 300 000 to 10 million plaque-forming units (PFU). The vaccine was shown to be safe and immunogenic [3, 7]. The vaccine is currently being tested in phase II and III trials in Guinea (clinical trials registration: PACTR201503001057193), Sierra Leone (PACTR201502001037220), and Liberia (NCT02344407). The recently published interim report of the phase III trial in Guinea demonstrated that the vaccine was 74.7%–100% effective [8]. The rVSV-ZEBOV vaccine requires storage at −70°C or less. Maintaining the cold chain of vaccine delivery is important since damage from accidental heating or freezing can result in potency loss for several vaccines commonly used in national immunization programs [9]. Previous stability studies of recombinant VSV suggest that this virus may be affected by pH, temperature, and protein concentration [10]. Owing to limited stability data for the rVSV-ZEBOV vaccine, it was important to evaluate these parameters before using the vaccine in the field during phase II and III trials. Prior to the start of clinical trials in West Africa, the decision about which dose to use had not been made. Therefore, we tested different vaccine concentrations.
Fisher Scientific, Waltham, Massachusetts) and 40°C (Termaks, Bergen, Norway). A standard consumer refrigerator (Electrolux, Stockholm, Sweden) was used for incubation at 4°C. The pH was measured by a Laquatwin Compact pH meter (Horiba Scientific, Kyoto, Japan). VSV Plaque Assay
The data are descriptively presented in graphs as PFU per milliliter. Averages, standard deviations, numbers of replicates, and P values are specified in Supplementary File 1. The number of PFU did not follow a normal distribution, and statistical testing was therefore performed using log10-transformed values. Statistical testing focused on assessing whether the viral titer in the vaccine was significantly affected by changes in temperature over time. An unpaired 2-tailed t test was performed, comparing the number of PFU per milliliter at every time point tested with the number at T0. A P value of .001; Figure 2B). After 14 days, the viral titer was significantly reduced (P < .001), and after 84 days the viral titer was reduced to approximately 2 × 104 PFU/mL, a reduction of 4 logs (Figure 2B). DISCUSSION
Here we report the short-term and long-term stability of the rVSV-ZEBOV vaccine in both undiluted and diluted form and at different temperatures. The short-term stability tests
BRIEF REPORT
•
JID
•
3
Downloaded from http://jid.oxfordjournals.org/ at KTH Royal Institute of Technology on February 8, 2016
Figure 2. A, The effect of dilution on pH. B, Stability of undiluted live attenuated vesicular stomatitis virus–vectored Ebola vaccine, rVSV-ZEBOV, during storage for 3 months at 4°C in the original vial. Samples were collected at days 0 (T0), 7, 14, 28, 56, and 84. The number of replicates included per time point was as follows: 12 (T0), 17 (day 14), and 18 (days 7, 28, 56, and 84). Long-term stability data originate from 1 experiment (1 vaccine vial). The asterisk indicates a significant difference (P < .001) from the value at T0. Abbreviation: PFU, plaque-forming units.
demonstrated that the vaccine can be stored at 4°C and 25°C for 24 hours at all three tested concentrations (1 × 108 PFU/ mL, 2 × 107 PFU/mL, and 3 × 106 PFU/mL) without significant loss of viral titer (Figure 1A–C). Storage of vaccine at 40°C caused a significant reduction in the vaccine titer at all concentrations tested (Figure 1A–C). These results are in line with stability data from the vaccine producer (Merck Vaccines, personal communication). These short-term stability results are also in agreement with those for a previously studied, non–EVD-relevant recombinant VSV formulation [10], demonstrating that stability decreases when the temperature is increased or the concentration of virus is decreased. The same report also showed that serum had a stabilizing effect on VSV infectivity [10]. Upon dilution, the concentration of serum in the vaccine is reduced, which may contribute to the lower stability of the most diluted form. The effects of temperature on the vaccine stability are in agreement with the stability of other rhabdoviruses (eg, rabies virus) [11, 12]. When diluted with NaCl, the pH of the vaccine decreased toward the level in the diluent (Figure 2A). Previous studies suggest that VSV is more sensitive to acidic conditions than to alkaline conditions [10]. This may be due to pH-sensitive glycoproteins [13]. However, the role of low pH for ZEBOV-GP function has been questioned [14]. The effect of the acidification on the infectivity of the rVSV-ZEBOV vaccine is therefore uncertain but is probably of less concern for the rVSV–ZEBOV-GP virus than for wild-type VSV, which is known to be dependent on low pH [13]. When opened immediately after thawing, the undiluted rVSV-ZEBOV vaccine in its original vial was stable for 1 week in a refrigerator (Figure 2B) but displayed a significant reduction in viral titer after 2 weeks. This result is not aligned with stability data from Merck (Merck Vaccines, personal communication). However, it is important to recognize that these results do not reflect the stability of sealed vials because the vials used in this experiment were opened immediately after thawing and because samples were collected repeatedly from the same vial. Most likely, the stability of vaccine from unopened vials would be better, but owing to the limited number of vaccine vials available to us, this was not possible to test in our laboratory. Although a significant reduction in vaccine concentration was observed after 2 weeks of refrigeration, the vaccine dose may still be immunogenic and protective. This could be investigated by further studies in animal models. In conclusion, the rVSV-ZEBOV vaccine is stable for at least 1 week after thawing, opening, and storage of the vaccine vial in a refrigerator. Undiluted and diluted vaccine maintains its potency for 24 hours at 25°C. Increased temperatures (ie, >25°C) reduce the stability of the vaccine. The rVSV-ZEBOV vaccine tested here has recently demonstrated promising preliminary results in the phase III vaccine trial in Guinea [8], and the dose used for vaccination was 2 × 107 PFU. This report provides timely assessment of the stability of this vaccine, indicates
stability at temperatures associated with refrigerators, and may be useful in the logistical planning for implementation of targeted use of the vaccine in the current and future Ebola outbreaks, once the vaccine is licensed for use. Supplementary Data Supplementary materials are available at http://jid.oxfordjournals.org. Consisting of data provided by the author to benefit the reader, the posted materials are not copyedited and are the sole responsibility of the author, so questions or comments should be addressed to the author.
References 1. Kanapathipillai R, Henao Restrepo AM, Fast P, et al. Ebola vaccine—an urgent international priority. N Engl J Med 2014; 371:2249–51.
4
•
JID
•
BRIEF REPORT
Downloaded from http://jid.oxfordjournals.org/ at KTH Royal Institute of Technology on February 8, 2016
Notes Acknowledgments. We thank the Public Health Agency of Canada, for donation of the vaccine vials to the World Health Organization; Bjørg Dystvold Nilsson, for coordination of the project at the Norwegian Institute of Public Health; Susanne Dudmann, for providing laboratory facilities to perform the work; and Hang Le, Remilyn Ramos-Ocao, and Wenche Holmen, for technical help in laboratory facilities. Financial support. This work was supported by the Norwegian Ministry of Foreign Affairs through the Research Council of Norway (grant 246662). Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
2. Lichty BD, Power AT, Stojdl DF, Bell JC. Vesicular stomatitis virus: re-inventing the bullet. Trends Mol Med 2004; 10:210–6. 3. Regules JA, Beigel JH, Paolino KM, et al. A recombinant vesicular stomatitis virus Ebola vaccine—preliminary report. N Engl J Med 2015; doi:10.1056/ NEJMoa1414216. 4. Marzi A, Feldmann H, Geisbert TW, Falzarano D. Vesicular stomatitis virus-based vaccines for prophylaxis and treatment of filovirus infections. J Bioterror Biodef 2011; pii:2157-2526-S1-004. 5. Feldmann H, Jones SM, Daddario-DiCaprio KM, et al. Effective post-exposure treatment of Ebola infection. PLoS Pathog 2007; 3:e2. 6. Lai L, Davey R, Beck A, et al. Emergency postexposure vaccination with vesicular stomatitis virus–vectored Ebola vaccine after needlestick. JAMA 2015; 313: 1249–55. 7. Agnandji ST, Huttner A, Zinser ME, et al. Phase 1 trials of rVSV Ebola vaccine in Africa and Europe—preliminary report. N Engl J Med 2015; doi:10.1056/ NEJMoa1502924. 8. Henao-Restrepo AM, Longini IM, Egger M, et al. Efficacy and effectiveness of an rVSV-vectored vaccine expressing Ebola surface glycoprotein: interim results from the Guinea ring vaccination cluster-randomised trial. Lancet 2015; 386:857–66. 9. Milstien JB, Galazka AM, Kartoglu UM, Zaffran M. Temperature sensitivity of vaccines. WHO/IVB/06.10. Geneva: World Health Organization, 2006. 10. Zimmer B, Summermatter K, Zimmer G. Stability and inactivation of vesicular stomatitis virus, a prototype rhabdovirus. Vet Microbiol 2013; 162:78–84. 11. Michalski F, Parks NF, Sokol F, Clark HF. Thermal inactivation of rabies and other rhabdoviruses: stabilization by the chelating agent ethylenediaminetetraacetic acid at physiological temperatures. Infect Immun 1976; 14:135–43. 12. Lawson KF, Bachmann P. Stability of attenuated live virus rabies vaccine in baits targeted to wild foxes under operational conditions. Can Vet J 2001; 42:368–74. 13. Mercer J, Schelhaas M, Helenius A. Virus entry by endocytosis. Annu Rev Biochem 2010; 79:803–33. 14. Bär S, Takada A, Kawaoka Y, Alizon M. Detection of cell-cell fusion mediated by Ebola virus glycoproteins. J Virol 2006; 80:2815–22.
