Different biological activity of CD154-SIVgp41 fusion protein vaccine component in naïve or pre-immune individuals

Background Trimeric gp41 might be an important target for neutralizing antibodies; however, the poor immunogenicity of this region may be due to its lack of exposure on native virus. CD154 (CD40L) is a trimeric glycoprotein found on activated CD4 T-cells that binds to CD40 on APCs and leads to B-cell activation and differentiation to plasma cells. We designed a novel immunogen with the potential for inducing neutralizing antibodies to gp41 and for stimulating activity on APC and B-cells.