Complexes of trophoblastic peptides and heat shock protein 70 as a novel contraceptive vaccine in a mouse model

• After binding to Hsp70, trophoblast-derived peptide can function as a novel vaccine to induce the trophoblast-specific T cell immune response, leading to the termination of early pregnancy.

The concept of contraceptive vaccines has interested reproductive biologists and immunologists for nearly 2 decades, but no approach has been approved. In this study, a new immunocontraceptive vaccine that targets placental trophoblasts was expored. We demonstrated that after in-vitro binding with heat shock protein 70, trophoblast-derived peptides can activate T cells both in vitro and in vivo. The activated T cells have a Th1 bias and specifically cause cytolysis of trophoblasts, leading to the termination of pregnancy. Such activated T cells seem to have an effect on early gestation, rather than influencing preimplantation. We did not observe side-effects of this vaccine in mice. In conclusion, a novel contraceptive strategy is described that uses heat shock protein 70-trophoblastic peptide complexes to generate a specific T-cell immune response against placental trophoblasts. This type of vaccine targeting the post-implantation phase does not generate a permanent effect but possibly raises an ethical issue.