Co-administration of Interleukin-2 Enhances Cellular and Humoral Immune Responses to HIV Vaccine DNA Prime/MVA Boost Regime

Interleukine-2(IL-2) is a growth factor for antigen-stimulated T lymphocytes and is responsible for ~T-cell clonal expansion after antigen recognition. It has been demonstrated that DNA vaccine-elicited immune responses in mice could be augmented substantially by using either an IL-2 protein or a plasmid expressing ~IL-2. Twenty mice, divided into four experimental groups, were immunized with: (1) sham plasmid; ^(2) HIV-1 DNA vaccine alone; (3) HIV-1 DNA vaccine and IL-2 protein; or (4) HIV-1 DNA vaccine and IL-2 plasmid, separately. All the groups were immunized 3 times at a 2-week interval. Fourteen days after the last DNA vaccine injection, recombinant MVA was injected into all the mice except those in group 1. ELISA and ELISPOT were employed to investigate the effect of IL-2 on DNA vaccine immune responses. The obtained results strongly indicate that the efficacy of HIV vaccine can be enhanced by co-administration of a plasmid encoding IL-2.

IL-15 increases the frequency of effectormemory CD8^(+) T cells in rhesus monkeys immunized with HIV vaccine

Several studies have suggested that interleukin(IL)-15 is a promising adjuvant that promotes cellular immunity when administered with human immunodeficiency virus(HIV)vaccine.Here we evaluated the effect of IL-15 plasmid on HIV-specific immune responses,especially cellular immunity,in eight rhesus monkeys.These monkeys were immunized three times with HIV DNA vaccine with or without IL-15 plasmid and boosted with recombinant Tiantan strain vaccinia virus-based HIV vaccine(rTV)22 weeks after the first immunization.Although we did not detect any significant differences in the HIV-specific CD81 T-cell response between monkeys with IL-15 coimmunization and monkeys with HIV vaccine alone,our results showed that the frequency of effector CD8^(+) memory T cells in the peripheral blood was significantly higher in monkeys with IL-15 coimmunization than those with HIV vaccine alone at almost all of the time points examined.Furthermore,the titers of anti-HIV antibodies were higher in Group T than those in Group C after rTV boosting.These findings in rhesus monkeys suggest that IL-15 may be useful as a cytokine adjuvant for HIV vaccine.

Adjuvant Effects of Dual Co-stimulatory Molecules on Cellular Responses to HIV Multiple-epitope DNA Vaccination

Designing adjuvants that can induce strong cytotoxic T cell responses is largely required for preparing DNA vaccines. In this study we explored dual costimulatory molecules 4-1BBL and OX40L as adjuvants to improve the efficiency of the HIV multiple-epitope DNA vaccine. When explored in the human dendritic cell-T cell based coculture system, dual costimulatory molecules significantly enhanced the anti-HIV T cell response of the HIV multiple-epitope DNA vaccine, as detected by intracellular cytokine staining to HIV antigens, cytokines accumulation in the cultures, and antigen-specific cytotoxic T lymphocyte responses. These results suggest that dual costimulatory molecules 4-1BBL and OX40L can effectively increase the potential of the HIV multiple-epitope antigen DNA vaccine and may provide an exciting approach for HIV therapy.

Structural sensitivity in HIV modeling: A case study of vaccination

Structural assumptions in infectious disease models,such as the choice of network or compartmental model type or the inclusion of different types of heterogeneity across individuals,might affect model predictions as much as or more than the choice of input parameters.We explore the potential implications of structural assumptions on HIV model predictions and policy conclusions.We illustrate the value of inference robustness assessment through a case study of the effects of a hypothetical HIV vaccine in multiple population subgroups over eight related transmission models,which we sequentially modify to vary over two dimensions:parameter complexity(e.g.,the inclusion of age and HCV comorbidity)and contact/simulation complexity(e.g.,aggregated compartmental vs.individual/disaggregated compartmental vs.network models).We find that estimates of HIV incidence reductions from network models and individual compartmental models vary,but those differences are overwhelmed by the differences in HIV incidence between such models and the aggregated compartmental models(which aggregate groups of individuals into compartments).Complexities such as age structure appear to buffer the effects of aggregation and increase the threshold of net vaccine effectiveness at which aggregated models begin to overestimate reductions.The differences introduced by parameter complexity in estimated incidence reduction also translate into substantial differences in cost-effectiveness estimates.Parameter complexity does not appear to play a consistent role in differentiating the projections of network models.