Specifically, inappropriately timed type-1 cytokine expression and polarisation of Th1 immunity in some circumstances can be counterproductive to both cell mediated and humoral responses. Examination of the anti-HIV p55-gag response following control i.n. FPV-HIV/i.m. VV-HIV
prime-boost immunisation demonstrated significant levels of both IgG1 and IgG2a in the sera of mice. More surprisingly, following immunisation of mice with the IL-4C118 adjuvant HIV vaccine, which induced enhanced high avidity HIV specific CD8+ T cells with IL-2 and IFN-γ expression also induced elevated HIV p55-gag IgG2a Panobinostat mw antibody responses six weeks post booster vaccination and was sustained over time. The recent RV144 trial included both a canarypox virus (very similar to rFPV) expressing gag/pol/env antigens followed by a protein booster to enhance the anti-env humoral response. Apoptosis inhibitor In that study the 31% protective efficacy observed was linked to antibody-mediated immunity, no cytotoxic CD8 T cell responses were observed, which may explain the partial protective efficacy. Interestingly, isotype switching and high levels of IgG2 antibodies directed towards the gag protein have been linked to protection, specifically in HIV controllers not carrying the ‘protective’ human leucocyte antigen HLA B alleles . Although, the mechanism by which gag-specific antibodies provided delayed progressions remains unknown, in some
HIV controllers, antibodies have shown to play a role in ADCC  and . It has been thought that production of IFN-γ and gag-specific antibodies particularly IgG2 may provide stimulation of plasmacytoide DC’s, which are typically reduced in HIV infected patients but not in controllers  and . These observations suggest that induction of gag-specific antibodies could play a pivotal role in providing the best protection possible against HIV-1. Our also IL-4R antagonist vaccine has shown to induce excellent long lasting IgG2a antibody immunity. The induction of both high quality T and robust B cell
immunity make our IL-4R antagonist HIV vaccine a good candidate for the future. Considering the similarity of the T cell responses between the IL-4C118 adjuvant HIV vaccine and our previous IL-13Rα2 adjuvanted vaccine study  the majority of the observed effects on the induced quality of HIV specific CD8+ T cell responses are likely due to the inhibition of IL-13 cell-signalling via the type-II IL-4R (IL-4Rα/IL-13Rα1). Sequestration of IL-13 using a decoy IL-13R will reduce IL-13 binding to both type II IL-4R and plasma membrane IL-13Rα2, however IL-4 will still available to engage with type-I/II IL-4R for signalling. In contrast, expression of the IL-4C118 antagonist will block both type-I/II IL-4R to IL-4 and IL-13 mediated signalling, however plasma membrane IL-13Rα2 could still bind free IL-13 (see Suppl. Diagram 1).