[Show abstract][Hide abstract] ABSTRACT: A hurdle facing DNA vaccine development is the ability to generate strong immune responses systemically and at local immune sites. We report a novel systemically administered DNA vaccination strategy using intramuscular codelivery of CCL27 or CCL28, which elicited elevated peripheral IFN-gamma and antigen-specific IgG while driving antigen-specific T-cell secretion of cytokine and antibody production in the gut-associated lymphoid tissue and lung. This strategy resulted in induction of long-lived antibody responses that neutralized influenza A/PR8/34 and protected mice from morbidity and mortality associated with a lethal intranasal viral challenge. This is the first example of the use of CCL27 and CCL28 chemokines as adjuvants to influence a DNA vaccine strategy, suggesting further examination of this approach for manipulation of vaccine-induced immunity impacting both quality and phenotype of responses.
[Show abstract][Hide abstract] ABSTRACT: DNA vaccination is an invaluable approach for immune therapy in that it lacks vector interference and thus permits repeated vaccination boosts. However, by themselves, DNA-based vaccines are typically poor inducers of Ag-specific immunity in humans and non-human primates. Cytokines, such as IL-12 and IL-15, have been shown to be potent adjuvants for the induction and maintenance of cellular immune responses, in particular during HIV infection. In this study, we examined the ability of therapeutic vaccination with SIV-DNA+IL-12 or IL-15 as molecular adjuvants to improve DNA vaccine potency and to enhance memory immune responses in SIV-infected macaques. Our results demonstrate that incorporating IL-12 into the vaccine induces SIV-specific CD8 effector memory T cell (T(EM)) functional responses and enhances the capacity of IFN-gamma-producing CD8 T(EM) cells to produce TNF. Lower levels of PD-1 were expressed on T cells acquiring dual function upon vaccination as compared with mono-functional CD8 T(EM) cells. Finally, a boost with SIV-DNA+IL-15 triggered most T cell memory subsets in macaques primed with either DNA-SIV or placebo but only CD8 T(EM) in macaques primed with SIV-DNA+IL-12. These results indicate that plasmid IL-12 and IL-15 cytokines represent a significant addition to enhance the ability of therapeutic DNA vaccines to induce better immunity.
The Journal of Immunology 06/2008; 180(12):7969-79. DOI:10.4049/jimmunol.180.12.7969 · 5.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The cell-mediated immune profile induced by a recombinant DNA vaccine was assessed in the simian/HIV (SHIV) and macaque model. The vaccine strategy included coimmunization of a DNA-based vaccine alone or in combination with an optimized plasmid encoding macaque IL-15 (pmacIL-15). We observed strong induction of vaccine-specific IFN-gamma-producing CD8(+) and CD4(+) effector T cells in the vaccination groups. Animals were subsequently challenged with 89.6p. The vaccine groups were protected from ongoing infection, and the IL-15 covaccinated group showed a more rapidly controlled infection than the group treated with DNA vaccine alone. Lymphocytes isolated from the group covaccinated with pmacIL-15 had higher cellular proliferative responses than lymphocytes isolated from the macaques that received SHIV DNA alone. Vaccine antigen activation of lymphocytes was also studied for a series of immunological molecules. Although mRNA for IFN-gamma was up-regulated after antigen stimulation, the inflammatory molecules IL-8 and MMP-9 were down-regulated. These observed immune profiles are potentially reflective of the ability of the different groups to control SHIV replication. This study demonstrates that an optimized IL-15 immune adjuvant delivered with a DNA vaccine can impact the cellular immune profile in nonhuman primates and lead to enhanced suppression of viral replication.
Proceedings of the National Academy of Sciences 12/2007; 104(47):18648-53. DOI:10.1073/pnas.0709198104 · 9.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the present era of increasing resistance of human immunodeficiency virus (HIV) to antiviral drugs, exploration of adjunct therapies directed at immune responses in combination with antiretroviral drugs may be of value for the treatment of acquired immunodeficiency syndrome. In this study, we designed a model for immune therapy using SIVmac251 infection in rhesus macaques. We explored the outcomes of primary infection on viral loads and the resulting T-cell immune responses in primates. The SIV-infected rhesus macaque model exhibited features similar to those observed in HIV-1 infection of humans. Major histocompatibility complex (MHC) segregation with viral loads were found to associate with viral containment and hence the duration of the disease-free latency period. Thus a better understanding of the relative roles of MHC class I allele in control of viral replication may provide important information for prophylactic or therapeutic vaccine designs. Mamu-A01 is significantly associated with higher immune response and control of viral replication. This allele is frequent in rhesus macaques of Indian origin (22%). Interestingly, Mamu-B01 (26% animals) was associated with lower immune responses and higher viral loads. Another allele, A08 was also predominantly present in 37% of the animals in this study. We observed higher viral replication in individual SIV-infected rhesus monkeys that did not demonstrate strong cellular immune responses. The results are important for understanding SIV disease progression in different MHC Mamu alleles and also for improving the interpretation and quality of pre-clinical studies in rhesus monkeys.
Journal of Medical Primatology 09/2006; 35(4-5):202-9. DOI:10.1111/j.1600-0684.2006.00179.x · 0.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: HIV-1 specific cellular immune responses play a significant part in controlling HIV-1 viral replication and are an important component of an HIV-1 vaccine induced immune response. We reported earlier that recombinant DNA vaccine delivered intramuscularly, and recombinant Listeria monocytogenes, delivered orally induced CD8+ and CD4+ T cell immune responses in rhesus macaques and that this vaccine protocol showed partial protection against an SIV239 challenge. In this paper, we have analyzed the SIV antigen-specific immune responses at the time of challenge and during the subsequent infection course. We find that the immune status of the animals, as measured by the frequency of antigen-specific IFN-gamma secreting peripheral blood mononuclear cells, at the time of challenge correlates more strongly with viral loads at set point than peak viral loads. The correlation between the immune response and viral load was strongest early, as viral set-point was just being established and disintegrates overtime. This study demonstrates the cellular immune response to SIV at the time of challenge of a nonhuman primate is able to impact on viral set-point following SIV239 challenge. Further, this study demonstrates that as virus replicates the T cell immune response to SIV antigens induced by the vaccine is modulated by antigen encountered by immune cells during viral replication.
[Show abstract][Hide abstract] ABSTRACT: DNA vaccines are a promising technology for the induction of Ag-specific immune responses, and much recent attention has gone into improving their immune potency. In this study we test the feasibility of delivering a plasmid encoding IL-15 as a DNA vaccine adjuvant for the induction of improved Ag-specific CD8(+) T cellular immune responses. Because native IL-15 is poorly expressed, we used PCR-based strategies to develop an optimized construct that expresses 80-fold higher than the native IL-15 construct. Using a DNA vaccination model, we determined that immunization with optimized IL-15 in combination with HIV-1gag DNA constructs resulted in a significant enhancement of Ag-specific CD8(+) T cell proliferation and IFN-gamma secretion, and strong induction of long-lived CD8(+) T cell responses. In an influenza DNA vaccine model, coimmunization with plasmid expressing influenza A PR8/34 hemagglutinin with the optimized IL-15 plasmid generated improved long term CD8(+) T cellular immunity and protected the mice against a lethal mucosal challenge with influenza virus. Because we observed that IL-15 appeared to mostly adjuvant CD8(+) T cell function, we show that in the partial, but not total, absence of CD4(+) T cell help, plasmid-delivered IL-15 could restore CD8 secondary immune responses to an antigenic DNA plasmid, supporting the idea that the effects of IL-15 on CD8(+) T cell expansion require the presence of low levels of CD4 T cells. These data suggest a role for enhanced plasmid IL-15 as a candidate adjuvant for vaccine or immunotherapeutic studies.
The Journal of Immunology 08/2005; 175(1):112-23. DOI:10.4049/jimmunol.175.1.112 · 5.36 Impact Factor