Oral Abstract Session 01 - Global HIV Vaccine Enterprise

POSTERS
Posters
Topic 1: Adjuvants, Immunogens and Inserts
P01.11
Evaluation of Latent Membrane Protein 1 as a Novel
Vaccine Adjuvant
J.M. Termini 1 , S. Gupta 1 , G.W. Stone 1
1 University of Miami, Miami, FL, USA
Background: The EBV protein Latent Membrane Protein-1
(LMP1) is known to constitutively activate B cells. The LMP1
signaling pathway mimics that of CD40, a molecule involved in
dendritic cell activation and maturation. Therefore we decided to
evaluate the use of LMP1 as a vaccine adjuvant for both dendritic
cell therapeutic vaccines and DNA-based vaccines for HIV.
Methods: To determine activity, LMP1 was analyzed using a
luciferase report assay for NF-kB and IFN-β. To establish if LMP1
could activate human monocyte-derived dendritic cells (DC),
LMP1 transfected DC were analyzed for activation/maturation
markers and cytokines. DC migration was determined using a
transwell-migration assay. LMP1 was also evaluated in a DNA
vaccination/flu challenge mouse model. To determine the
benefits of incorporating LMP1 into a DC therapeutic vaccine,
LMP1 was tested in a tumor DC therapy mouse model.
Results: LMP1 activated high levels of NF-kB and IFN-β when
evaluated using a luciferase reported assay. On primary DC,
LMP1 induced DC activation, maturation, and proinflammatory
cytokines. LMP1 induced 2-fold higher migration rates compared
to the mature-DC control. As a DNA vaccine for flu, the addition
of LMP1 provided superior TNF-α and IFN-γ responses. LMP1
vaccinated animals cleared virus more quickly and in the highdose
lethal flu challenge, LMP1 afforded more protection. Finally,
LMP1 enhanced a DC therapeutic vaccine in a tumor model.
Tumor progression was slowed compared to antigen-loaded DC
alone and positive control mimic-matured DC.
Conclusion: These data suggest that LMP1 is an effective vaccine
adjuvant. LMP1 can enhance the activation, maturation, and
functional activity of DC. LMP1 can inducing a strong CD8+ T
cell response in several mouse models, most notably the flu
viral challenge model. LMP1 increased antigen-specific CD8+ T
cells, improved survival to lethal flu high-dose challenge, and
slowed tumor progression. These results suggest that LMP1 is a
promising adjuvant for prophylactic vaccines for HIV.
100
AIDS Vaccine 2012
P01.12
Potent Induction of Antibody-Secreting B-Cells
by Human Dermal-Derived CD14+ Dendritic Cells
Triggered by Dual Toll-like Receptor Ligation
K. Matthews 1 , N.P. Chung 1 , P.J. Klasse 1 , J.P. Moore 1 ,
R.W. Sanders 2
1 Weill Cornell Medical College, New York, NY, USA; 2 Academic
Medical Center, Amsterdam, Netherlands
Background: A goal of HIV-1 vaccine development is to induce
broadly neutralizing antibodies. However, the Env complex is
poorly immunogenic and requires potent adjuvants. Given the
pivotal role of TLRs and DCs in initiating and tuning adaptive
immune responses, TLR agonists are attractive adjuvants.
CD14+ dermal DCs (CD14+ DDCs) have a natural capacity to
stimulate naïve B-cells, so targeting these cells with TLR ligands
is a rational approach to inducing humoral responses.
Methods: Migratory cells were collected after culturing skin
for 24 h. CD14+ DDCs were purified using CD14 magnetic
beads, stimulated with TLR ligand(s) and analyzed for cytokine
expression (ELISA/qPCR) and phenotype after 48 h. Naïve
B-cells were stimulated with TLR ligand(s) plus CD40L and IL-2,
either alone or in the presence of CD14+ DDCs, and analyzed
for proliferation, phenotype and IgG/IgA secretion. TLR-ligand
stimulated DDCs were incubated with allogeneic naive CD4+
T-cells for 6 days before T-cell derived cytokines were quantified.
Results: CD14+ DDCs express mRNA for TLRs 1−9, but respond
differentially to single or paired TLR ligands. Compared to
single ligands, some combinations were particularly effective,
increasing the expression of B-cell stimulatory cytokines and
maturation of the DDCs. These combinations were R-848 plus
Poly(I:C); R-848 plus LPS; Pam3CSK4 plus Poly(I:C); LPS plus
Poly(I:C). Selected TLR agonist pairs (R-848 plus either LPS or
Poly(I:C)) were superior to individual agents at boosting the
capacity of CD14+ DDCs to induce naïve B-cells to proliferate and
differentiate into CD27+CD38+ B-cells that secrete high levels
of IgG and IgA. These selected TLR ligand combinations also
induced CD14+ DDCs to promote differentiation of Th1, but not
Th2, Th17 or TFH cells.
Conclusion: Two TLR ligand combinations potently activate CD14+
DDCs to have enhanced B-cell stimulatory capacity, and could be
used to improve humoral immune responses to HIV-1 Env.