HIV-1 Adenoviral Vector Vaccines Expressing Multi-Trimeric BAFF and 4-1BBL Enhance T Cell Mediated Anti-Viral Immunity

Abstract

Adenoviral vectored vaccines have shown considerable promise but could be improved by molecular adjuvants. Ligands in the TNF superfamily (TNFSF) are potential adjuvants for adenoviral vector (Ad5) vaccines based on their central role in adaptive immunity. Many TNFSF ligands require aggregation beyond the trimeric state (multi-trimerization) for optimal biological function. Here we describe Ad5 vaccines for HIV-1 Gag antigen (Ad5-Gag) adjuvanted with the TNFSF ligands 4-1BBL, BAFF, GITRL and CD27L constructed as soluble multi-trimeric proteins via fusion to Surfactant Protein D (SP-D) as a multimerization scaffold. Mice were vaccinated with Ad5-Gag combined with Ad5 expressing one of the SP-D-TNFSF constructs or single-chain IL-12p70 as adjuvant. To evaluate vaccine-induced protection, mice were challenged with vaccinia virus expressing Gag (vaccinia-Gag) which is known to target the female genital tract, a major route of sexually acquired HIV-1 infection. In this system, SP-D-4-1BBL or SP-D-BAFF led to significantly reduced vaccinia-Gag replication when compared to Ad5-Gag alone. In contrast, IL-12p70, SP-D-CD27L and SP-D-GITRL were not protective. Histological examination following vaccinia-Gag challenge showed a dramatic lymphocytic infiltration into the uterus and ovaries of SP-D-4-1BBL and SP-D-BAFF-treated animals. By day 5 post challenge, proinflammatory cytokines in the tissue were reduced, consistent with the enhanced control over viral replication. Splenocytes had no specific immune markers that correlated with protection induced by SP-D-4-1BBL and SP-D-BAFF versus other groups. IL-12p70, despite lack of anti-viral efficacy, increased the total numbers of splenic dextramer positive CD8+ T cells, effector memory T cells, and effector Gag-specific CD8+ T cells, suggesting that these markers are poor predictors of anti-viral immunity in this model. In conclusion, soluble multi-trimeric 4-1BBL and BAFF adjuvants led to strong protection from vaccinia-Gag challenge, but the protection was independent of standard immune markers. Soluble multi-trimeric SP-D-4-1BBL and SP-D-BAFF provide a novel technology to enhance adenoviral vector vaccines against HIV-1.

Binding Studies of TNF Receptor Superfamily (TNFRSF) Receptors on Intact Cells

“…First, strong receptor activation by poorly active soluble ligand trimers can be restored by multimerization, e.g. by oligomerization with antibodies recognizing an epitope/tag not interfering with receptor binding or by genetically enforced formation of hexameric, nonameric, or dodecameric molecules (14,19,22,23,(25)(26)(27)(28)(29)(30). Second, inefficient receptor activation by soluble ligand trimers can be overcome by binding to the extracellular matrix or by artificial cell surface immobilization using genetically engineered trimeric variants of soluble TNF ligands (31).…”

Ex VivoNicotine Stimulation Augments the Efficacy of Human Peripheral Blood Mononuclear Cell-Derived Dendritic Cell Vaccination via Activating Akt-S6 Pathway

“…MHC class I and II molecules are the components of antigenic peptide-MHC complex for antigen presentation [ 10 – 14 ]. While CD80/CD86 are important costimulatory molecules in T-cell-APC interaction [ 2 , 22 ], 4-1BBL, which sends signals to 4-1BB-expressing cells [ 23 , 24 ], was found to play critical roles in preventing activation-induced cell death [ 25 , 26 ]. To explore the exact effect of nicotine stimulation on the expression of surface molecules, hu-imDCs were conferred with nicotine exposure and the expression of CD80, 4-1BBL, and MHC class I and II molecules was determined by flow cytometry.…”

4-1BBL Enhances CD8+ T Cell Responses Induced by Vectored Vaccines in Mice but Fails to Improve Immunogenicity in Rhesus Macaques

“…Indeed, two previous reports have shown enhancement of the response in mice by the use of murine 4-1BBL in combination with other costimulatory molecules when compared to the response when each was administered alone [50], [51]. More recently increased anti-viral efficacy of a HAdV5-gag vector in mice was observed by immunisation with a HAdV5 expressing a trimeric complex of murine 4-1BBL and murine BAFF fused to surfactant protein-D [52], further providing support for the use of 4-1BBL in a complex.…”