Dendritic cells (DC) are critical to induce protective antiviral T cell responses, but previous HIV-1 vaccine studies suggest that improvement of DC function is essential for boosting HIV-1 specific immunity. TANK-binding Kinase 1 (TBK-1) is a key regulator of DC maturation in response to HIV-1 and to prime polyfunctional specific T cells. Our objective is to evaluate the efficacy of a vaccine based on TBK1-engineered DCs controlling HIV-1 infection in vivo using the humanized bone marrow, liver and thymus (hBLT) mouse model.
A total of 24 humanized hBLT-mice were generated for the study. A fraction of autologous CD34+ hematopoietic stem cells (HSC) were used to differentiate DC in the presence of FLT3L, IL-7, SCF and GMCSF. Three separate groups of 8 humanized hBLT-mice were injected with HSC-derived DCs cultured in media (MED), gag peptides alone (GAG) or in combination with 2´-3´-c-AMP and Poly-I:C TBK-1 adjuvants (GAG-ADJ) and infected intravenously with 10,000 TCID50 of JRCSF HIV-1. Plasma HIV-1 viral loads, polyfunctional T cell responses from peripheral blood and lymphoid tissue and CD4+ T cell counts were assessed at 3 and 6 weeks post-infection. Presence of CD8+ T cells and p24+ infected cells was determined by immunofluorescence in lymphoid nodes. Statistical differences were calculated using a Mann Whitney or a Chi-square tests.
All groups of hBLT-mice became infected with HIV-1, however animals vaccinated with autologous GAG-ADJ DCs exhibited a partial but significant reduction of HIV-1 plasma viral loads at 3 weeks p.i. compared to control groups (p=0.021). These differences were accompanied by higher polyfunctional profiles in circulating CD8+ T cells in the GAG-ADJ group (p=0.005), suggesting partial control of viral replication at early time points. At 6 weeks post-vaccination, plasma viral loads were similar across different groups of vaccinated mice, however Polyfunctional T cells were specifically observed in the spleen from GAG-ADJ and a less severe depletion of CD4+ T cell lymphocytes was detected in these animals compared to GAG mice (p=0.05 vs p=0.0078). Moreover, increased clusters of CD8+ T cells excluding infected HIV-1 p24+ cells from specific areas within the lymph node were also observed in these animals (p=0.001).
Engineered TBK-1 DCs are able to improve parameters of immune control of HIV-1 infection in the hBLT-mouse model and might be useful for subsequent vaccine studies.