Cytokines as adjuvants for improving anti-HIV responses
Morrow, Matthew P; Weiner, David B
From the Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
Correspondence to D. Weiner, 422 Curie Blvd, 505 Stellar Chance Labs, University of Pennsylvania, Philadelphia, PA 19104, USA. E-mail: email@example.com
Since AIDS was first identified over 25 years ago [1,2], scientific advances have significantly expanded our understanding of the immune system, providing new tools for immune modulation and immunization strategies. The employment of DNA, protein subunits, and recombinant viral vectors in vaccination against HIV have been reviewed elsewhere [3–14]. The current article focuses on the use of new adjuvants as additions to HIV vaccination and immunotherapy regimens. By adjuvant, we refer to an immune potentiator in a vehicle . A wide variety of adjuvants has been tested for their abilities to elicit cellular and humoral responses to HIV antigens in vivo. The goal of studies employing new adjuvants is that their inclusion will promote a stronger and more directed immune response than those generated by current approaches.
Cytokine adjuvants: overview
A number of adjuvants are in use in both animal models as well as in human vaccination [16–18]. These include PAMP (pathogen associated molecular patterns) and co-stimulatory molecules that have been discussed previously and will not be reviewed here [19,20–33]. Currently, the only adjuvant approved for use in human vaccination is alum . While alum does enhance the ability of the immune system to respond to non-self antigens after vaccination, its ability to polarize the immune system is quite poor . More should be expected from the next generations of adjuvants in that they should be able to direct the immune response towards a desired outcome. The employment of Th1-associated cytokines such as interferon (IFN)-γ, interleukin (IL)-2, -12, and -15 [9–14,34–38] in animal models induces type-1, antigen specific cellular immune responses [19,39,40–42]. In contrast, the inclusion of cytokines known to polarize the immune system towards the induction of Th2 responses such as IL-4, IL-10 and granulocyte-macrophage cell stimulating factor [40,43,44] augments antigen-specific humoral immune responses [28,40,45]. Thus cytokine adjuvants may be considered improved to an adjuvant such as alum when the aim of the immunization is to direct the immune response towards a specific Th subtype.
Challenge of an HIV vaccine
Standard methods of vaccination, such as the use of subunit vaccines or whole inactivated virus, have not been able to induce broadly neutralizing immune responses against HIV in their current forms. Thus, the drive to develop a broadly neutralizing approach continues to be an important goal.
The questions posed by this challenge are: what type of immunity needs to be induced for an HIV vaccine to be effective and what types of vaccination can induce these responses? While neutralizing antibodies can be generated in vivo , total antibody responses during infection have limited antiviral effects . Moreover, as infection may theoretically be not only a consequence of viral passage from person to person, but also a result of passage of infected cells from person to person, the use of antibodies as an effective blockade to the establishment of infection may have limitations. Importantly, the STEP Study, the first study of a pure T cell-based approach from a vector platform that induces low level T-cell responses, has been disappointing . Therefore, for an HIV vaccine, the generation of more robust cytotoxic T lymphocyte (CTL) responses that have the potential to be cross reactive against diverse viral HIV strains seems to be needed in addition to the induction of antiviral antibodies. Such a vaccine should be one which induces a massive expansion of HIV-specific CTL which have high cytotoxic potential, are long-lived, and home to mucosal tissues. Accordingly, when infection at mucosal sites occurs, the speed and intensity of the CTL response could feasibly better control or eliminate infection of new target cells. Furthermore other immune parameters should also be expected, including the induction of polyfunctionality, and long lasting T-cell memory.
Cytokine adjuvants and vaccination
Vaccines that have benefited from the use of adjuvants span multiple classes, such as subunit vaccines, vaccines employing viral vectors and DNA vaccines. For example, the addition of adjuvants to administered peptide antigens such as gp120 can augment immune activity in vivo, resulting in durable responses postvaccination . The use of viral vectors as a means of delivering an antigen of interest for vaccination continues to have wide popularity both in academia [50–53] as well as industry [54–56]. Employing viruses such as Modified Vaccinia Virus Ankara (MVA) allows for delivery of antigens into the cytoplasm of target cells, thus providing expression through MHC Class I and subsequent generation of CTL responses [57,58]. In addition to MVA, recombinant adenoviruses are being employed more often as viral vectors in vaccination [51,52,54–57]. While there are a number of adenovirus serotypes, recombinant replication-defective adenovirus serotype 5 (rAd5) is the most commonly employed variant for vaccination against HIV and is able to induce antigen specific CTL responses [51,52,54,59]. The type of immune responses generated by rAd5 vectors has prompted clinical trials by the NIH-VRC as well as pharmaceutical companies such as Merck (see Table 2). These trials have shown this system to be safe and well tolerated in healthy adults in addition to inducing T-cell mediated immune responses . However, data from the STEP study suggests that levels of CTL activity induced by these vectors are not protective in humans . In fact questions of the relationship of the vector to acquisition of infection in these trials is under investigation. Thus, improving the potency of this approach and understanding its limitations are critical. Overall, adjuvants have not been employed as widely in combination with this rAd5 vaccination as they have with other vaccination methods. Data from the STEP trial and other studies may indicate that an analysis of adjuvants in conjunction with recombinant adenovirus-based vectors is warranted.
Out of all currently studied routes of vaccination, DNA vaccines have likely benefited the most from the continuing study and expansion of cytokine adjuvants. DNA vaccination employs the introduction, intramuscularly or intradermally, of a DNA vector encoding a gene of interest . Studies suggest that plasmid DNA vectors can transfect and express in skeletal muscle, macrophages and dendritic cells in vivo . Vaccination with SIV antigens encoded by DNA plasmids leads to reduced viremia in macaques after challenge with SIVmac251 . Responses to DNA vaccination are further increased when it is used in conjunction with in vivo electroporation in animal models [63,64,83]. IFN-γ, IL-2, -12, -15 and -21 have all been employed in multiple studies of DNA vaccines targeted against HIV or SIV, and are generally administered in plasmid form as well [39,65–69]. These adjuvants do, indeed augment CD8 cell responses to antigens delivered via DNA vaccination, with IL-2/Ig and IL-12 in particular creating robust anti-HIV CTL responses [65,66]. Mouse studies using IL-12 in conjunction with a plasmid encoding an HIV Gag/Pol construct show a 4.5-fold increase in specific CD8 cell lysis of target cells over inoculation with the Gag/Pol construct alone . IL-12, both on its own and in co-administration with IL-15 also induces potent type-1 responses in rhesus macaques, leading to substantial control of viremia, lower viral set point, and greatly improved clinical outcomes after challenge with SHIV 89.6P . Additionally, a recent study shows that use of IL-15 in conjunction with DNA encoding SHIV antigens leads to significant protection against SHIV 89.6P challenge in macaques . These studies suggest that the use of IL-12 and IL-15 in DNA vaccination against HIV or SIV leads to the generation of CTL responses that are improved with respect to HIV vaccine development.
Previous studies have suggested that IL-15, in particular, can prime CTL to better degranulate in response to TCR ligation . It may be of some benefit, then, to study further this cytokine in an HIV infection model. Additionally, IFN-γ has shown positive results in inducing CTL activity in mouse models . However, our own studies show that the use of IFN-γ as an adjuvant in DNA vaccination of non-human primates may not yield similar results (Table 1). This result may suggest that adjuvants that work in mouse models may not necessarily show the same potency in primates. To that end, further studies need to be performed with IL-15 in primates, as the employment of this cytokine in mouse vaccination studies has resulted in the generation of HIV-specific CD8 cell responses that are able to function partially independent of CD4 cells. This CTL characteristic can be of crucial importance for an HIV vaccine . Positive results observed in vaccination studies of non-human primates using challenge with highly pathogenic viruses closely related to HIV suggest that DNA vaccination with cytokine adjuvants has potential for vaccines in humans. A number of clinical trials are gearing up or currently underway, including vaccination with HIV-DNA constructs augmented with plasmid IL-12 or IL-15 (Table 2).
Therapeutic post-infection immunization
In contrast to vaccination, whose aim is to prevent the establishment of productive infection by HIV, immunotherapy regimens using viral antigens are aimed at promoting or augmenting immune responses to HIV in patients who are already infected. The hypothesis for such approaches is that re-exposing the patient's immune system to antigen in a structured fashion may lead to the development of a more potent and directed immune response, which may reduce or eliminate the need for HAART in the infected individual. Design of therapeutic immunizations should likely have the same endpoint as HIV vaccines: expanding HIV-specific CTL. However, the methods used are likely to be different from those utilized in a vaccine. Patients receiving therapeutic immunizations are already HIV positive and thus are immunocompromised to some extent as a result of infection. Therefore, therapeutic immunizations will need to be designed in such a way as to account for the fact that CD4 cell help will be limited at best. The inclusion of adjuvants that promote CD8 cell responses that are more independent of CD4 T-cell help will be of great importance, as will the inclusion of adjuvants that promote better antigen-specific priming of CTL.
Cytokine adjuvants and post-infection immunization
In the same vein as vaccines, immunotherapies have been studied using DNA, whole inactivated gp120-deleted virus and viral vectors [73–78]. Such therapies have shown promise both in animal models  as well as in human clinical trials [77,78]. Specifically, a study employing IL-2 in conjunction with a viral vector delivering SIV antigens showed that this type of immunization of SIVmac251 infected macaques substantially augmented SIV-specific CD8 T-cell responses . Additionally, therapeutic immunization of rhesus macaques with DNA encoding SIV antigens after infection with SIVmac251 resulted in considerably increased cellular immune responses along with long lasting reduction in viral loads after the animals were released from HAART . In regards to augmenting the responses generated by therapeutic immunization, specific cytokines seem to have great potential, especially IL-15 and IL-21. Both cytokines have been shown to induce increases in perforin and granzyme B levels in CD8 cells cultured ex vivo, giving CTL greater cytotoxic potential [71,81]. Moreover, peripheral blood mononuclear cells isolated from HIV positive patients have shown higher increases in granularity in response to IL-15 and IL-21 treatment than those taken from healthy individuals . Additionally, including IL-15 as an adjuvant in therapeutic immunization may help in the induction of antiviral CD8 cell activity by antigen presenting cells. CD8 T cells from HIV infected subjects co-cultured with mature dendritic cells restored the ability of the CD8 cells to inhibit viral replication by a non-cytotoxic mechanism . This effect was associated with the production of IL-15 by the dendritic cells . Such a result suggests that therapeutic immunization of HIV positive patients with antigen co-administered with IL-15 could also promote the stimulation of better CD8 cell anti-HIV responses. This effect is on top of the afore mentioned fact that IL-15 can induce the generation of CD8 cells that function somewhat independently of CD4 cell help .
Increased use of adjuvants in both vaccines and therapeutic immunizations for HIV infection should bring renewed vigor in attempts to induce lasting, robust immune responses against the virus. These adjuvants would boost HIV-specific immunity, modulate immune phenotype, and their use gives the scientific community a greater measure of control over what types of immune responses are driven in response to HIV antigen. Specific adjuvants including IL-12, IL-15 as well specific chemokines can strongly polarize the adaptive immune response towards a desired Th subtype. These look particularly important for clinical evaluation. Some adjuvants elicit strong responses from the innate immune system as well, such as IL-8 , and should be further studied in primate systems. This is an additional benefit of specific adjuvants, the induction of both the adaptive and innate arms of the immune system in response to HIV. While at this time there appears to be no single cytokine that is superior to others for use in vaccination and immune therapy, adjuvants such as IL-12 and IL-15 and specific chemokines such as Mip1α show promise in prophylactic vaccination approaches while IL-15 and IL-21 may prove beneficial for use in immune therapy for HIV infection.
1. CDC. Pneumocystis pneumonia—
Los Angeles. MMWR
2. Gottlieb MS, Schroff R, Schanker HM, Weisman JD, Fan PT, Wolf RA, et al
. Pneumocystis carinii pneumonia and mucosal candidiasis in previously healthy homosexual men: evidence of a new acquired cellular immunodeficiency. NEJM 1981; 305:1425.
3. Hinkula J. Clarification of how HIV-1 DNA and protein immunizations may be better used to obtain HIV-1-specific mucosal and systemic immunity. Expert Rev Vaccines 2007; 6(2):203–212. Review.
4. Hokey DA, Weiner DB. DNA vaccines for HIV: challenges and opportunities. Springer Semin Immunopathol 2006; 28(3):267–279. Review.
5. Dale CJ, Thomson S, De Rose R, Ranasinghe C, Medveczky CJ, Pamungkas J, et al
. Prime-boost strategies in DNA vaccines. Methods Mol Med 2006; 127:171–197. Review.
6. Letvin NL. Progress toward an HIV vaccine. Annu Rev Med 2005; 56:213–223. Review.
7. Liniger M, Zuniga A, Naim HY. Use of viral vectors for the development of vaccines. Expert Rev Vaccines 2007; 6(2):255–266. Review.
8. Duerr A, Wasserheit JN, Corey L. HIV vaccines: new frontiers in vaccine development
. Clin Infect Dis
, 2006 15;43 (4)
9. Tatsis N, Ertl HC. Adenoviruses as vaccine vectors. Molecular Therapy 2004; 10(4):616–629. Review.
10. Gomez-Roman VR, Robert-Guroff M. Adenoviruses as vectors for HIV vaccines. AIDS Rev 2003; 5(3):178–185. Review.
11. Kent S, De Rose R, Rollman E. Drug evaluation: DNA/MVA prime-boost HIV vaccine. Curr Opin Investig Drugs 2007; 8(2):159–167. Review.
12. Hanke T, McMichael AJ, Dorrell L. Clinical experience with plasmid DNA- and modified vaccinia virus Ankara-vectored human immunodeficiency virus type 1 clade A vaccine focusing on T-cell induction. J Gen Virol 2007; 88(Pt 1):1–12. Review.
13. McBurney SP, Ross TM. Developing broadly reactive HIV-1/AIDS vaccines: a review of polyvalent and centralized HIV-1 vaccines. Curr Pharm Des 2007; 13(19):1957–1964. Review.
14. Phogat S, Wyatt R. Rational modifications of HIV-1 envelope glycoproteins for immunogen design. Curr Pharm Des 2007; 13(2):213–227. Review.
15. Pashine A, Valiante N, Ulmer JB. Targeting the innate immune response with improved vaccine adjuvants. Nature Med 2005; 11:S63.
16. Evans TG, McElrath MJ, Matthews T, Montefiori D, Weinhold K, Wollf M, et al
. QS-21 promotes an adjuvant effect allowing for reduced antigen dose during HIV-1 envelope subunit immunization in humans. Vaccine 2001; 19(15–16):2080–2091.
17. O'Hagan DT, Ugozzoli M, Barackman J, Singh M, Kazzaz J, Higgins K, et al
. Microparticles in MF59, a potent adjuvant combination for a recombinant protein vaccine against HIV-1. Vaccine 2000; 18(17):1793–1801.
18. Burdman J, Powell M, Newman M. Vaccine Design: Subunit & Adjuvant Approach. Springer; Edition 1 1995.
19. Boyer JD, Robinson TM, Kutzler MA, Parkinson R, Calarota SA, Sidhu MK, et al
. SIV DNA vaccine co-administered with IL-12 expression plasmid enhances CD8 SIV cellular immune responses in cynomolgus macaques. J Med Primatol 2005; 34(5–6):262–270.
20. Hemmi H, Akira S. TLR signalling and the function of dendritic cells. Chem Immunol Allergy 2005; 86:120–135. Review.
21. Freytag LC, Clements JD. Mucosal adjuvants
2005 7;23 (15)
22. Wheeler AW, Marshall JS, Ulrich JT. A Th1-inducing adjuvant, MPL, enhances antibody profiles in experimental animals suggesting it has the potential to improve the efficacy of allergy vaccines. Int Arch Allergy Immunol 2001; 126(2):135–139.
23. Moore A, McCarthy L, Mills KH. The adjuvant combination monophosphoryl lipid A and QS21 switches T cell responses induced with a soluble recombinant HIV protein from Th2 to Th1
1999 4;17 (20–21)
24. Otero M, Calarota SA, Felber B, Laddy D, Pavlakis G, et al
. Resiquimod is a modest adjuvant for HIV-1 gag-based genetic immunization in a mouse model
2004 16;22 (13–14)
25. Teleshova N, Kenney J, Van Nest G, Marshall J, Lifson JD, et al
. Local and systemic effects of intranodally injected CpG-C immunostimulatory-oligodeoxyribonucleotides in macaques
. J Immunology
26. Daftarian P, Sharan R, Haq W, Ali S, Longmate J, et al
. Novel conjugates of epitope fusion peptides with CpG-ODN display enhanced immunogenicity and HIV recognition
2005 16;23 (26)
27. Aggarwal P, Pandey RM, Seth P. Augmentation of HIV-1 subtype C vaccine constructs induced immune response in mice by CpG motif 1826-ODN. Viral Immunol 2005; 18(1):213–223.
28. Speiser DE, Lienard D, Rufer N, Rubio-Godoy V, Rimoldi D, Lejuene F, et al
. Rapid and strong human CD8+ T cell responses to vaccination with peptide, IFA, and CpG oligodeoxynucleotide 7909. J Clin Invest 2005; 115(3):739–746.
29. Albu DI, Jones-Trower A, Woron AM, Stellrecht K, Broder CC, Metzger DW. Intranasal vaccination using interleukin-12 and cholera toxin subunit B as adjuvants to enhance mucosal and systemic immunity to human immunodeficiency virus type 1 glycoproteins. J Virology 2003; 77(10):5589–5597.
30. Du X, Zheng G, Jin H, Kang Y, Wang J, Xiao C, et al
. The adjuvant effects of co-stimulatory molecules on cellular and memory responses to HBsAg DNA vaccination. J Gene Med 2007; 9(2):136–146.
31. Shankar P, Schlom J, Hodge JW. Enhanced activation of rhesus T cells by vectors encoding a triad of costimulatory molecules (B7-1, ICAM-1, LFA-3). Vaccine 2001; 20(5–6):744–755.
32. Tsuji T, Hamajima K, Ishii N, Aoki I, Fukushima J, Xin KQ, et al
. Immunomodulatory effects of a plasmid expressing B7-2 on human immunodeficiency virus-1-specific cell-mediated immunity induced by a plasmid encoding the viral antigen. Eur J Immunol 1997; 27(3):782–787.
33. Akira S, Uematsuand S, Takeuchi O. Pathogen Recognition and Innate Immunity. Cell 2006; 124:783.
34. Petrovsky N. Novel human polysaccharide adjuvants with dual Th1 and Th2 potentiating activity. Vaccine 2006; 24(Supplement 2):S26–S29.
35. Chang HD, Radbruch A. The pro- and anti-inflammatory potential of interleukin-12. Ann N Y Acad Sci 2007; 1109:40–46.
36. Kajiyama Y, Umezu-Goto M, Kobayashi N, Takahashi K, Fukuchi Y, Mori A. IL-2-Induced IL-9 Production by Allergen-Specific Human Helper T Cell Clones. Int Arch Allergy Immunol 2007; 143(Suppl 1):71–75.
37. Vesosky B, Flaherty DK, Turner J. Th1 cytokines facilitate CD8-T-cell-mediated early resistance to infection with Mycobacterium tuberculosis in old mice. Infect Immun 2006; 74(6):3314–3324.
38. Abebe F, Mustafa T, Nerland AH, Bjune GA. Cytokine profile during latent and slowly progressive primary tuberculosis: a possible role for interleukin-15 in mediating clinical disease. Clin Exp Immunol 2006; 143(1):180–192.
39. Kim JJ, Nottingham LK, Tsai A, Lee DJ, Maguire HC, Oh J, et al
. Antigen-specific humoral and cellular immune responses can be modulated in rhesus macaques through the use of IFN-gamma, IL-12, or IL-18 gene adjuvants. J Med Primatol 1999; 28(4–5):214–223.
40. Kim JJ, Yang JS, Montaner L, Lee DJ, Chalian AA, Weiner DB. Coimmunization with IFN-gamma or IL-2, but not IL-13 or IL-4 cDNA can enhance Th1-type DNA vaccine-induced immune responses in vivo. J Interferon Cytokine Res 2000; 20(3):311–319.
41. Bolesta E, Kowalczyk A, Wierzbicki A, Eppolito C, Kaneko Y, et al
. Increased level and longevity of protective immune responses induced by DNA vaccine expressing the HIV-1 Env glycoprotein when combined with IL-21 and IL-15 gene delivery
. J Immunology
2006 1;177 (1)
42. Kutzler MA, Robinson TM, Chattergoon MA, Choo DK, Choo AY, et al
. Coimmunization with an optimized IL-15 plasmid results in enhanced function and longevity of CD8 T cells that are partially independent of CD4 T cell help
. J Immunology
. 2005 1;175 (1)
43. Lamkhioued B, Gounni AS, Aldebert D, Delaporte E, Prin L, Capron A, et al
. Synthesis of type 1 (IFN gamma) and type 2 (IL-4, IL-5, and IL-10) cytokines by human eosinophils
. Ann N Y Acad Sci
44. Chu Y, Xia M, Lin Y, Li A, Wang Y, Liu R, et al
. Th2-dominated antitumor immunity induced by DNA immunization with the genes coding for a basal core peptide PDTRP and GM-CSF. Cancer Gene Ther 2006; 13(5):510–519.
45. Weiss SH, Goedert JJ, Gartner S, Popovic M, Waters D, Markham P, et al
. Risk of human immunodeficiency virus (HIV-1) infection among laboratory workers. Science 1988; 239:68–71.
46. Frost SD, Wrin T, Smith DM, Kosakovsky Pond SL, Liu Y, Paxinos E, et al
. Neutralizing antibody responses drive the evolution of human immunodeficiency virus type 1 envelope during recent HIV infection
2005 20;102 (51)
47. McDougall B, Nymark MH, Landucci G, Forthal D, Robinson WE Jr. Predominance of detrimental humoral immune responses to HIV-1 in AIDS patients with CD4 lymphocyte counts less than 400/mm3. Scand J Immunol 1997; 45(1):103–111.
49. McKee HJ, T'sao PY, Vera M, Fortes P, Strayer DS. Durable cytotoxic immune responses against gp120 elicited by recombinant SV40 vectors encoding HIV-1 gp120 +/- IL-15
. Genet Vaccines Ther
. 200;2 (1)
50. Earl PL, Americo JL, Wyatt LS, Anne Eller L, Montefiori DC, Byrum R, et al
. Recombinant modified vaccinia virus Ankara provides durable protection against disease caused by an immunodeficiency virus as well as long-term immunity to an orthopoxvirus in a non-human primate. Virology 2007; 366(1):84–97.
51. Santra S, Seaman MS, Xu L, Barouch DH, Lord CI, Lifton MA, et al
. Replication-defective adenovirus serotype 5 vectors elicit durable cellular and humoral immune responses in nonhuman primates. J Virology 2005; 79(10):6516–6522.
52. Peng B, Voltan R, Cristillo AD, Alvord WG, Davis-Warren A, Zhou Q, et al
. Replicating Ad-recombinants encoding non-myristoylated rather than wild-type HIV Nef elicit enhanced cellular immunity. AIDS 2006; 20(17):2149–2157.
53. Goonetilleke N, Moore S, Dally L, Winstone N, Cebere I, Mahmoud A, et al
. Induction of multifunctional human immunodeficiency virus type 1 (HIV-1)-specific T cells capable of proliferation in healthy subjects by using a prime-boost regimen of DNA- and modified vaccinia virus Ankara-vectored vaccines expressing HIV-1 Gag coupled to CD8+ T-cell epitopes. J Virology 2006; 80(10):4717–4728.
54. Tobery TW, Dubey SA, Anderson K, Freed DC, Cox KS, Lin J, et al
. A comparison of standard immunogenicity assays for monitoring HIV type 1 gag-specific T cell responses in Ad5 HIV Type 1 gag vaccinated human subjects. AIDS Res Hum Retroviruses 2006; 22(11):1081–1090.
55. Shiver JW, Fu TM, Chen L, Casimiro DR, Davies ME, Evans RK, et al
. Replication-incompetent adenoviral vaccine vector elicits effective anti-immunodeficiency-virus immunity. Nature 2002; 415(6869):331–335.
56. Lubeck MD, Natuk RJ, Chengalvala M, Chanda PK, Murthy KK, Murthy S, et al
. Immunogenicity of recombinant adenovirus-human immunodeficiency virus vaccines in chimpanzees following intranasal administration. AIDS Res Hum Retroviruses 1994; 10(11):1443–1449.
57. van Ginkel FW, McGhee JR, Liu C, Simecka JW, Yamamoto M, Frizzell RA, et al
. Adenoviral gene delivery elicits distinct pulmonary-associated T helper cell responses to the vector and to its transgene. J Immunology 1997; 159(2):685–693.
58. Woodberry T, Gardner J, Elliott SL, Leyrer S, Purdie DM, Chaplin P, et al
. Prime boost vaccination strategies: CD8 T cell numbers, protection, and Th1 bias. J Immunology 2003; 170(5):2599–2604.
59. Sumida SM, Truitt DM, Kishko MG, Arthur JC, Jackson SS, Gorgone DA, et al
. Neutralizing antibodies and CD8+ T lymphocytes both contribute to immunity to adenovirus serotype 5 vaccine vectors. J Virology 2004; 78(6):2666–2673.
60. Duerr A, Wasserheit JN, Corey L. HIV Vaccines: New Frontiers in Vaccine Development. Clinical Infectious Diseases 2006; 43:500–511.
61. Giri M, Ugen KE, Weiner DB. DNA vaccines against human immunodeficiency virus type 1 in the past decade. Clin Microbiol Rev 2004; 17(2):370–389. Review.
62. Rosati M, von Gegerfelt A, Roth P, Alicea C, Valentin A, Robert-Guroff M, et al
. DNA Vaccines Expressing Different Forms of Simian Immunodeficiency Virus Antigens Decrease Viremia upon SIVmac251 Challenge
. J Virology. 79 (13)
63. Luckay A, Sidhu MK, Kjeken R, Megati S, Chong SY, Roopchand V, et al
. Effect of plasmid DNA vaccine design and in vivo electroporation on the resulting vaccine-specific immune responses in rhesus macaques. J Virology 2007; 81(10):5257–5269.
64. Widera G, Austin M, Rabussay D, Goldbeck C, Barnett SW, Chen M, et al
. Increased DNA vaccine delivery and immunogenicity by electroporation in vivo. J Immunology 2000; 164(9):4635–4640.
65. Barouch DH, Craiu A, Kuroda MJ, Schmitz JE, Zheng XX, Santra S, et al
. Augmentation of immune responses to HIV-1 and simian immunodeficiency virus DNA vaccines by IL-2/Ig plasmid administration in rhesus monkeys. PNAS 2000; 97(8):4192–4197.
66. Chong SY, Egan MA, Kutzler MA, Megati S, Masood A, Roopchard V, et al
. Comparative ability of plasmid IL-12 and IL-15 to enhance cellular and humoral immune responses elicited by a SIVgag plasmid DNA vaccine and alter disease progression following SHIV(89.6P) challenge in rhesus macaques. Vaccine 2007; 25(26):4967–4982.
67. Boyer JD, Robinson TM, Kutzler MA, Vansant G, Hokey DA, et al
. Protection against simian/human immunodeficiency virus 89.6P in macaques after coimmunization with SHIV antigen and IL-15 plasmid
In Press 2007.
68. Horiuchi R, Akahata W, Kuwata T, Enose Y, Ido E, Suzuki H, et al
. DNA vaccination of macaques by a full-genome SHIV plasmid that has an IL-2 gene and produces non-infectious virus particles. Vaccine 2006; 24(17):3677–3685.
69. Bolesta E, Kowalczyk A, Wierzbicki A, Eppolito C, Kaneko Y, Takiguchi M, et al
. Increased level and longevity of protective immune responses induced by DNA vaccine expressing the HIV-1 Env glycoprotein when combined with IL-21 and IL-15 gene delivery. J Immunology 2006; 177(1):177–191.
70. Kim JJ, Simbiri KA, Sin JI, Dang K, Oh J, Dentchev T, et al
. Cytokine molecular adjuvants modulate immune responses induced by DNA vaccine constructs for HIV-1 and SIV. J Interferon Cytokine Res 1999; 19(1):77–84.
71. White L, Krishnan S, Strbo N, Liu H, Kolber MA, Lichtenheld MG, et al
. Differential effects of IL-21 and IL-15 on perforin expression, lysosomal degranulation, and proliferation in CD8 T cells of patients with human immunodeficiency virus-1 (HIV). Blood 2006; 109(9):3873–3880.
72. Ihata A, Watabe S, Sasaki S, Shirai A, Fukushima J, Hamajima K, et al
. Immunomodulatory effect of a plasmid expressing CD40 ligand on DNA vaccination against human immunodeficiency virus type-1. Immunology 1999; 98(3):436–442.
73. Kim JJ, Trivedi NN, Nottingham LK, Morrison L, Tsai A, Hu Y, et al
. Modulation of amplitude and direction of in vivo immune responses by co-administration of cytokine gene expression cassettes with DNA immunogens
. Eur J Immunol
. Mar;28 (3)
74. Boyer JD, Cohen AD, Ugen KE, Edgeworth RL, Bennett M, Shah A, et al
. Therapeutic immunization of HIV-infected chimpanzees using HIV-1 plasmid antigens and interleukin-12 expressing plasmids. AIDS 2000; 14(11):1515–1522.
75. Hardy GA, Imami N, Nelson MR, Sullivan AK, Moss R, Aasa-Chapman M, et al
. A phase I, randomized study of combined IL-2 and therapeutic immunisation with antiretroviral therapy. J Immune Based Ther Vaccines 2007; 5:6.
76. Uberla K, Rosenwirth B, Ten Haaft P, Heeney J, Sutter G, Erfle V. Therapeutic immunization with Modified Vaccinia Virus Ankara (MVA) vaccines in SIV-infected rhesus monkeys undergoing antiretroviral therapy. J Med Primatol 2007; 36(1):2–9.
77. Kilby JM, Bucy RP, Mildvan D, Fischl M, Santana-Bagur J, Lennox J, et al
. A randomized, partially blinded phase 2 trial of antiretroviral therapy, HIV-specific immunizations, and interleukin-2 cycles to promote efficient control of viral replication (ACTG A5024). J Infect Dis 2006; 194(12):1672–1676.
78. Gudmundsdotter L, Sjodin A, Bostrom AC, Hejdeman B, Theve-Palm R, Alaeus A, et al
. Therapeutic immunization for HIV. Springer Semin Immunopathol 2006; 28(3):221–230.
79. Nacsa J, Edghill-Smith Y, Tsai WP, Venzon D, Tryniszewska E, Hryniewicz A, et al
. Contrasting effects of low-dose IL-2 on vaccine-boosted simian immunodeficiency virus (SIV)-specific CD4+ and CD8+ T cells in macaques chronically infected with SIVmac251. J Immunology 2005; 174(4):1913–1921.
80. von Gergerfelt AS, Rosati M, Alicea C, Valentin A, Roth P, Bear J, et al
. Long-Lasting Decrease in Viremia in Macaques Chronically Infected with Simian Immunodeficiency Virus SIVmac251 after Therapeutic DNA Immunization. J Virology 2007; 81(4):1972–1979.
81. Tamang DL, Redelman D, Alves BN, Vollger L, Bethley C, Hudig D. Induction of granzyme B and T cell cytotoxic capacity by IL-2 or IL-15 without antigens: multiclonal responses that are extremely lytic if triggered and short-lived after cytokine withdrawal. Cytokine 2006; 36(3–4):148–159.
82. Castelli J, Thomas EK, Gilliet M, Liu YJ, Levy JA. Mature dendritic cells can enhance CD8+ cell noncytotoxic anti-HIV responses: the role of IL-15. Blood 2004; 103(7):2699–2704.
83. Hirao LA, Wu L, Khan AS, Satishchandran A, Draghia-Akli R, Weiner DB, Title: Intradermal/Subcutaneous immunization by electroporation improves plasmid vaccine delivery and potency in pigs and rhesus macaques. Vaccines
, In Press 2007.
84. Babu P, Chidekel A, Shaffer TH. Association of interleukin-8 with inflammatory and innate immune components in bronchoalveolar lavage of children with chronic respiratory diseases. Clinica Chimica Acta 2004; 350(1):195–200.
© 2008 Lippincott Williams & Wilkins, Inc.
What does "Remember me" mean?
By checking this box, you'll stay logged in until you logout. You'll get easier access to your articles, collections,
media, and all your other content, even if you close your browser or shut down your
To protect your most sensitive data and activities (like changing your password),
we'll ask you to re-enter your password when you access these services.
What if I'm on a computer that I share with others?
If you're using a public computer or you share this computer with others, we recommend
that you uncheck the "Remember me" box.
Data is temporarily unavailable. Please try again soon.