Recombinant Ov-ASP-1, a Th1-Biased Protein Adjuvant Derived from the Helminth Onchocerca volvulus, Can Directly Bind and Activate Antigen-Presenting Cells

We previously reported that rOv-ASP-1, a recombinant Onchocerca volvulus activation associated protein-1, was a potent adjuvant for recombinant protein or synthetic peptide-based Ags. In this study, we further evaluated the adjuvanticity of rOv-ASP-1 and explored its mechanism of action. Consistently, recombinant full-length spike protein of SARS-CoV or its receptor-binding domain in the presence of rOv-ASP-1 could effectively induce a mixed but Th1-skewed immune response in immunized mice. It appears that rOv-ASP-1 primarily bound to the APCs among human PBMCs and triggered Th1-biased proinflammatory cytokine production probably via the activation of monocyte-derived dendritic cells and the TLR, TLR2, and TLR4, thus suggesting that rOv-ASP-1 is a novel potent innate adjuvant.