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and
Robert G. Ulrich2
BD Technologies, Research Triangle Park, North Carolina 27709,1 U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland 217022
Received 1 August 2006/ Returned for modification 15 September 2006/ Accepted 21 September 2006
| ABSTRACT |
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| INTRODUCTION |
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Most licensed and new vaccines under clinical development, including rPA, are administered by i.m. or subcutaneous injection using conventional needles and syringes. However, recent studies demonstrate that vaccine delivery to the skin can increase the magnitude of the immune response and, in some cases, do so using less vaccine than required with i.m. injection (1, 2, 10, 12, 18-20, 22). For example, clinical studies evaluating intradermal (i.d.) delivery of influenza vaccine have suggested that dose sparing relative to i.m. administration can be achieved (1, 10). Although conventional needles can be used for i.d. delivery, the injection method (the Mantoux technique) requires extensive training and is difficult to perform. Furthermore, it is difficult to precisely control the injection depth using this technique, which often results in the misdirection of a portion of the administered dose into the poorly immune-reactive subcutaneous tissue underlying the skin or leakage of the dose from the injection site after removal of the large-bore needle. We are developing microneedle-based delivery systems for epidermal and dermal administration of vaccines (3, 16-18). These microneedle-based devices accurately deposit the vaccine to a defined depth within the skin. Using these devices, we previously reported that rabbits were completely protected against inhalational anthrax following i.d. administration of three 50-µg doses of rPA (18). Here, we compared microneedle-based i.d. delivery to i.m. injection using graded doses of rPA. We used a dose range (10, 0.2, or 0.08 µg of rPA) that was previously shown to provide 100% survival at the highest dose, 83% survival at the intermediate dose, and 33% survival at the lowest dose following two i.m. inoculations of rPA plus adjuvant (13). Our results suggest that i.d. delivery enables vaccine dose sparing during the early stages of the immune response and that similar levels of protection against aerosol spore challenge can be achieved by this new route of administration and by conventional i.m. injection.
| MATERIALS AND METHODS |
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Female New Zealand White rabbits (Charles River Laboratories, Wilmington, MA) were immunized with 10, 0.2, or 0.08 µg of rPA via either i.d. or i.m. injection. The rPA protein was provided by VaxGen, Inc. (Brisbane, CA) and was mixed with Alhydrogel (E.M. Sergeant Pulp and Chemical Co., Inc, Clifton, NJ) just before injection. The amount of Alhydrogel per dose of vaccine was constant across all groups (35 µl of Alhydrogel containing 10 mg/ml Al = 0.35 mg Al per dose), while the amount of rPA and diluent per dose of vaccine varied by condition (rPA stock solution was provided at 3.1 mg/ml). The total dosing volume across all groups was 100 µl per rabbit. Immunizations were performed on day 0 (d0) and d28, and blood samples were collected on days 0, 14, 28, 42, and 56 from the marginal ear vein. i.d. injections were performed using a stainless steel 1-mm, 34-gauge microneedle and a 1-ml syringe (BD Technologies, Research Triangle Park, NC); the procedure was performed as described previously (3, 18). i.m. injections were administered into the quadriceps muscle by use of a 27-guage needle (1/2-in. length) and a 1-ml syringe (BD, Franklin Lakes, NJ).
Immune response assays and aerosol challenge. A quantitative enzyme-linked immunosorbent assay kit for rabbit immunoglobulin G (IgG) (Bethyl Laboratories, Montgomery, TX) was used with modifications. The first two columns of Maxisorp 96-well plates (Nalge Nunc, Rochester, NY) were coated with the provided capture antibody for the IgG standard curve. The remaining wells were coated with 1 µg/ml rPA in 0.05 M carbonate coating buffer, pH 9.6, for sample analysis. The plates were then incubated overnight at 4°C. Plates were blocked for 1 h at room temperature (RT) in blocking buffer (50 mM Tris, 0.14 M NaCl, 1% bovine serum albumin, pH 8.0) and then washed three times with wash solution (50 mM Tris, 0.14 M NaCl, 0.05% Tween 20, pH 8.0). IgG standards were prepared using the provided primary standard solution in a range from 7.8 to 500 ng/ml. Twofold serial dilutions of serum samples were performed (ranging from 1:50 to 1:6,400). Plates were incubated for 1 h at RT and washed three times. Plates were incubated for 1 h at RT following the addition of horseradish peroxidase-conjugated detection antibody (1:100,000) and then developed by 30 min of RT incubation with 3,3',5,5'tetramethylbenzidine (TMB; Sigma, St. Louis, MO) substrate. The enzymatic reaction was stopped with 0.5 M H2SO4, and the optical densities were read at 450 nm (Tecan U.S., Research Triangle Park, NC). The rabbit IgG calibration curve was used to semiquantitatively determine the PA-specific IgG concentrations in the samples. A four-parameter logistic fit model was used to predict sample concentrations from the calibration curve. Toxin neutralizing antibody (TNA) titers were determined as described previously (15, 18). Rabbits were challenged with Ames strain anthrax spores as described previously (18, 21). The mean inhaled dose was equivalent to 263 ± 97 50% lethal doses (LD50) of Ames spores, calculated according to methods described previously (18, 21).
Statistics. Antibody titers between groups were compared statistically by t test. Values reported represent two-tailed P values. The relationship between d56 anti-PA antibody levels and survival was determined by logistic regression.
| RESULTS |
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Rabbits were given an aerosol challenge with Ames strain anthrax spores at approximately d80. Survival rates are depicted in Fig. 2A. Complete protection was evident in the group immunized with 10 µg of rPA via the i.d. route, while the corresponding group immunized i.m. displayed 71% survival. Considerably lower levels of protection, ranging from 13 to 29%, were observed across all groups immunized using lower antigen doses. All of the unimmunized control rabbits died within 2 to 3 days postchallenge (Fig. 2A). Although only partial protection was observed in groups immunized with low doses (0.2 or 0.08 µg) of rPA, there was a modest 1- to 3-day delay in the time to death in these groups compared to controls. Nonsurviving rabbits in the group immunized i.m. with 10 µg of antigen also showed a 2- to 3-day delay in the time to death relative to controls (Fig. 2A).
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10,000 and PA-specific IgG levels of
200 µg/ml did not survive, while other animals with more-than-10-fold-reduced levels of TNA titers and PA-specific IgG survived. Nonetheless, d56 serum IgG levels were a significant predictor of survival by logistic regression analysis (P < 0.0025). | DISCUSSION |
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The survival rates we observed following i.d. and i.m. vaccinations were substantially lower per dose of antigen administered than those in a previously reported study, in which 83% survival was observed following two i.m. administered doses of 0.2 µg rPA, and 33% survival was found with the use of 0.08 µg of antigen (13). These differences may be due, in part, to differences in the amounts of Alhydrogel (500 µg in previous studies versus 350 µg per injection in this study) or in the biopotencies of the vaccines used in the two studies. Overall, the results highlight the inherent variability associated with in vivo challenge models that make it difficult to directly compare results between separate studies conducted at different times in different laboratories. In general, rabbits with the highest levels of PA-specific serum IgG and the most elevated TNA titers survived lethal aerosol challenge, whereas those with lower responses died. Consistent with the results of others (13, 21), we observed that anti-PA antibody levels were a significant predictor of survival.
The use of minimally invasive, easy-to-use delivery devices such as the microneedle-based system described herein could potentially reduce the burden on highly skilled medical practitioners for biodefense vaccination. In addition, increased ease of use may enable biodefense vaccines to be administered at numerous decentralized locations rather than at large, centralized vaccination centers that could represent targets for terrorist attack and facilitate the spread of infection. Our results suggest that i.d. delivery induces a level of protection against inhalational anthrax in a rabbit model that is comparable to that achieved via i.m. injection using conventional needle and syringe technology. On a dose-by-dose basis, i.d. delivery provided increased immune responses over i.m. injection during the early stages of the immune response. In addition, dose sparing was evident at the early time points. These improvements relative to i.m. injection, if recapitulated in humans, could potentially be of importance to biodefense vaccination in both prophylactic and postexposure therapeutic settings. Future studies will involve clinical evaluation of the i.d. route for anthrax immunization as a possible alternative to the standard i.m. route.
| ACKNOWLEDGMENTS |
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Financial support was provided, in part, by funding from the U.S. Army Medical Research and Materiel Command, agreement number DAMD17-03-2-0037 (J.A.M.), and from the Defense Threat Reduction Agency, agreement number C.2 X001 04 RD B (R.G.U.).
| FOOTNOTES |
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Published ahead of print on 9 October 2006. ![]()
Present address: Tulane National Primate Research Center, Division of Microbiology, Covington, LA 70433. ![]()
| REFERENCES |
|---|
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|
|---|
| 1. | Belshe, R. B., F. K. Newman, J. Cannon, C. Duane, J. Treanor, C. Van Hoecke, B. J. Howe, and G. Dubin. 2004. Serum antibody responses after intradermal vaccination against influenza. N. Engl. J. Med. 351:2286-2294. |
| 2. | Carcaboso, A. M., R. M. Hernandez, M. Igartua, J. E. Rosas, M. E. Patarroyo, and J. L. Pedraz. 2004. Enhancing immunogenicity and reducing dose of microparticulated synthetic vaccines: single intradermal administration. Pharm. Res. 21:121-126.[CrossRef][Medline] |
| 3. | Dean, C. H., J. B. Alarcon, A. M. Waterston, K. Draper, R. Early, F. Guirakhoo, T. P. Monath, and J. A. Mikszta. 2005. Cutaneous delivery of a live, attenuated chimeric flavivirus vaccine against Japanese encephalitis (ChimeriVax-JE) in non-human primates. Hum. Vaccines 1:106-111. |
| 4. | Flick-Smith, H. C., J. E. Eyles, R. Hebdon, E. L. Waters, R. J. Beedham, T. J. Stagg, J. Miller, H. O. Alpar, L. W. Baillie, and E. D. Williamson. 2002. Mucosal or parenteral administration of microsphere-associated Bacillus anthracis protective antigen protects against anthrax infection in mice. Infect. Immun. 70:2022-2028. |
| 5. | Friedlander, A. M., S. L. Welkos, M. L. Pitt, J. W. Ezzell, P. L. Worsham, K. J. Rose, B. E. Ivins, J. R. Lowe, G. B. Howe, P. Mikesell, and W. B. Lawrence. 1993. Postexposure prophylaxis against experimental inhalation anthrax. J. Infect. Dis. 167:1239-1243.[Medline] |
| 6. | Gorse, G. J., W. Keitel, H. Keyserling, D. N. Taylor, M. Lock, K. Alves, J. Kenner, L. Deans, and M. Gurwith. 2006. Immunogenicity and tolerance of ascending doses of a recombinant protective antigen (rPA102) anthrax vaccine: a randomized, double-blinded, controlled, multicenter trial. Vaccine 24:5950-5959.[CrossRef][Medline] |
| 7. | Griffith, K. S., P. Mead, G. L. Armstrong, J. Painter, K. A. Kelley, A. R. Hoffmaster, D. Mayo, D. Barden, R. Ridzon, U. Parashar, E. H. Teshale, J. Williams, S. Noviello, J. F. Perz, E. E. Mast, D. L. Swerdlow, and J. L. Hadler. 2003. Bioterrorism-related inhalational anthrax in an elderly woman, Connecticut, 2001. Emerg. Infect. Dis. 9:681-688.[Medline] |
| 8. | Ivins, B. E., M. L. M. Pitt, P. F. Fellows, J. W. Farchaus, G. E. Benner, D. M. Waag, S. F. Little, G. W. Anderson, P. H. Gibbs, and A. M. Friedlander. 1998. Comparative efficacy of experimental anthrax vaccine candidates against inhalation anthrax in rhesus macaques. Vaccine 16:1141-1148.[CrossRef][Medline] |
| 9. | Jernigan, J. A., D. S. Stephens, D. A. Ashford, C. Omenaca, M. S. Topiel, M. Galbraith, M. Tapper, T. L. Fisk, S. Zaki, T. Popovic, R. F. Meyer, C. P. Quinn, S. A. Harper, S. K. Fridkin, J. J. Sejvar, C. W. Shepard, M. McConnell, J. Guarner, W. J. Shieh, J. M. Malecki, J. L. Gerberding, J. M. Hughes, and B. A. Perkins. 2001. Bioterrorism-related inhalational anthrax: the first 10 cases reported in the United States. Emerg. Infect. Dis. 7:933-944.[Medline] |
| 10. | Kenney, R. T., S. A. Frech, L. R. Muenz, C. P. Villar, and G. M. Glenn. 2004. Dose sparing with intradermal injection of influenza vaccine. N. Engl. J. Med. 351:2295-2301. |
| 11. | Kenney, R. T., J. M. Yu, M. Guebre-Xabier, S. A. Frech, A. Lambert, B. A. Heller, L. R. Ellingsworth, J. E. Eyles, E. D. Williamson, and G. M. Glenn. 2004. Induction of protective immunity against lethal anthrax challenge with a patch. J. Infect. Dis. 190:774-782.[CrossRef][Medline] |
| 12. | Kurugol, Z., S. Erensoy, S. Aksit, A. Egemen, and A. Bilgic. 2001. Low-dose intradermal administration of recombinant hepatitis B vaccine in children: 5-year follow-up study. Vaccine 19:3936-3939.[CrossRef][Medline] |
| 13. | Little, S. F., B. E. Ivins, P. F. Fellows, M. L. Pitt, S. L. Norris, and G. P. Andrews. 2004. Defining a serological correlate of protection in rabbits for a recombinant anthrax vaccine. Vaccine 22:422-430.[CrossRef][Medline] |
| 14. | Little, S. F., B. E. Ivins, W. M. Webster, P. F. Fellows, M. L. Pitt, S. L. Norris, and G. P. Andrews. 2006. Duration of protection of rabbits after vaccination with Bacillus anthracis recombinant protective antigen vaccine. Vaccine 24:2530-2536.[CrossRef][Medline] |
| 15. | Little, S. F., S. H. Leppla, and A. M. Friedlander. 1990. Production and characterization of monoclonal antibodies against the lethal factor component of Bacillus anthracis lethal toxin. Infect. Immun. 58:1606-1613. |
| 16. | Mikszta, J. A., J. B. Alarcon, J. M. Brittingham, D. E. Sutter, R. J. Pettis, and N. G. Harvey. 2002. Improved genetic immunization via micromechanical disruption of skin-barrier function and targeted epidermal delivery. Nat. Med. 8:415-419.[CrossRef][Medline] |
| 17. | Mikszta, J. A., M. I. Haider, and R. J. Pettis. 2006. Microneedles for drug and vaccine delivery. When will the dream become a reality? p. 309-325. In J. Wille (ed.), Skin delivery systems. Transdermals, dermatologicals, and cosmetic actives. Blackwell Press, Ames, Iowa. |
| 18. | Mikszta, J. A., V. J. Sullivan, C. Dean, A. M. Waterston, J. B. Alarcon, J. P. Dekker, J. M. Brittingham, J. Huang, C. R. Hwang, M. Ferriter, G. Jiang, K. Mar, K. U. Saikh, B. G. Stiles, C. J. Roy, R. G. Ulrich, and N. G. Harvey. 2005. Protective immunization against inhalational anthrax: a comparison of minimally invasive delivery platforms. J. Infect. Dis. 191:278-288.[CrossRef][Medline] |
| 19. | Nagafuchi, S., S. Kashiwagi, S. Imayama, J. Hayashi, and Y. Niho. 1998. Intradermal administration of viral vaccines. Rev. Med. Virol. 8:97-111.[CrossRef][Medline] |
| 20. | Pancharoen, C., J. Mekmullica, U. Thisyakorn, S. Kasempimolporn, H. Wilde, and C. Herzog. 2005. Reduced-dose intradermal vaccination against hepatitis A with an aluminum-free vaccine is immunogenic and can lower costs. Clin. Infect. Dis. 41:1537-1540.[CrossRef][Medline] |
| 21. | Pitt, M. L., S. F. Little, B. E. Ivins, P. Fellows, J. Barth, J. Hewetson, P. Gibbs, M. Dertzbaugh, and A. M. Friedlander. 2001. In vitro correlate of immunity in a rabbit model of inhalational anthrax. Vaccine 19:4768-4773.[CrossRef][Medline] |
| 22. | Playford, E. G., P. G. Hogan, A. S. Bansal, K. Harrison, D. Drummond, D. F. M. Looke, and M. Whitby. 2002. Intradermal recombinant hepatitis B vaccine for healthcare workers who fail to respond to intramuscular vaccine. Infect. Control Hosp. Epidemiol. 23:87-90.[CrossRef][Medline] |
| 23. | Williamson, E. D., I. Hodgson, N. J. Walker, A. W. Topping, M. G. Duchars, J. M. Mott, J. Estep, C. LeButt, H. C. Flick-Smith, H. E. Jones, H. Li, and C. P. Quinn. 2005. Immunogenicity of recombinant protective antigen and efficacy against aerosol challenge with anthrax. Infect. Immun. 73:5978-5987. |
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