1) [5], [12] and [28]. Assessment of vaccine-induced immune responses can be

achieved through a range of T cell, B cell, and innate immunity assays. Many of the same assays and reagents used to develop preventive vaccines can be applied to therapeutic vaccine research. However, there is no consensus on assays that would allow for trial comparisons, and on methods to address biological variability in baseline viral load and other responses in HIV positive individuals. One promising and relatively new approach is the measurement of the ability of HIV-specific CD8 T cells to kill infected CD4 T cell targets, which is just beginning to be evaluated in the context of vaccine trials [29] and [30]. Given the focus on curative interventions, a primary outcome measure in most modern therapeutic vaccines studies is the size of the “latent Ion Channel Ligand Library reservoir”, perhaps best defined as the residual virus that remains in the setting of apparently effective combination ART, and is able to give rise to recrudescent viral replication and progressive disease

after ART is stopped. At least part of this “reservoir” is composed of virus in latently infected cells, rather than actively replicating virus. Although viral outgrowth assays used to quantify the replication-competent reservoir are viewed as the gold standard, there is no current standard, high-throughput SB431542 cost measure of the reservoir. Measures of plasma HIV RNA, cell-associated HIV RNA (unspliced, multiply spliced) and cell-associated DNA (integrated, unintegrated, total) are being developed, but these are unlikely to fully resolve the difficulties of distinguishing replication-competent latent proviruses from defective ones [31]. Measurement of the HIV reservoir both in vitro and in vivo has emerged as an important potential biomarker that will require additional development and optimization [32] and [33]. Drs. Nicole Frahm, Felipe Garcia, Jeff Jacobson, John Eldridge, Jean Boyer and George Pavlakis

discussed the lessons that can be learned from past therapeutic vaccine studies in humans (Fig. 2). Therapeutic vaccine candidates recently tested have utilized a variety of platforms and approaches including DNA, viral vectors (alone and with DNA) mafosfamide [34], [35] and [36] dendritic cells (DC) [37] and [38] and peptides [27], [39] and [40], using a variety of antigens together in some case with adjuvants and immune modulators. A few clinical trials of therapeutic vaccines to date have induced a transitory reduction in viral load in the context of treatment interruption. Some of these trials have shown modest delays in time to viral load rebound, prolongation of time until ART needs to be resumed, and/or sustained reductions of viral load (typically less than 0.5 log10 copies RNA/mL) [12].