Vaccine potential of Ebola virus VP24, VP30, VP35, and VP40 proteins.

Previous vaccine efforts with Ebola virus Zaire (EBOV-Z) emphasized the potential protective efficacies of immune responses to the surface glycoprotein and the nucleoprotein. To determine whether the VP24, VP30, VP35, and VP40 proteins are also capable of eliciting protective immune responses, these genes were expressed from alphavirus replicons and used to vaccinate BALB/c and C57BL/6 mice. Although all of the VP proteins were capable of inducing protective immune responses, no single VP protein protected both strains of mice tested. VP24, VP30, and VP40 induced protective immune responses in BALB/c mice, whereas C57BL/6 mice survived challenge only after vaccination with VP35. Passive transfer of immune sera to the VP proteins did not protect unvaccinated mice from lethal disease. The demonstration that the VP proteins are capable of eliciting protective immune responses to EBOV-Z indicates that they may be important components of a vaccine designed to protect humans from Ebola hemorrhagic fever.