 Signal sequences play a critical role in sorting nascent secretory and membrane proteins, which has been conserved from bacteria through eukaryotes. A plant signal sequence was used to drive human papillomavirus, HPV, model antigens into the human secretory pathway, resulting in a strong humeral response against both E7 and L2. This activity in mammalian cells may be responsible for the observed increased humeral response to DNA-based vaccines, opening new perspectives in the design of DNA vaccines. This article was authored by Silvia Massa, Francesca Paulini, John Franca Cersio, and others.