A designed Tat immunogen generates enhanced anti-Tat C-terminal antibodies.

HIV-1 Tat has been identified as an attractive target for vaccine development and is currently under investigation in clinical trials as both a therapeutic and preventative vaccine for HIV-1. The Tat C-terminal region is of significant importance for its extracellular activity. In this study, we designed two recombinant Tat immunogens, Tat(B41-100N) and Tat(B41-100C), with two extended Tat C-terminal regions (41-100 aa) and compared their humoral immune response with native Tat. Interestingly, our results showed that Tat(B41-100C) elicited a higher antibody titer than Tat and Tat(B41-100N) in both mice and rabbits. The recombinant fusion protein-based epitope analysis showed that Tat(B41-100C) induced a remarkably enhanced humoral immune response against extended Tat C-terminal regions containing residues 38-100, 49-100 and 60-100. Our study demonstrates that the designed Tat(B41-100C) presents a designed immunogenicity that elicits enhanced Tat-specific antibodies especially against extended Tat C-terminal regions.