New Ebolavirus Vaccine Protects Against Lethal Infection in Animal Models

A new experimental Ebola vaccine is one step closer to realization, having proven its ability to protect against lethal infections in animal models. The researchers report their findings in the April 2009 issue of the Journal of Virology.

Ebolaviruses (EBOVs), the cause of severe hemorrhagic fever in humans and nonhuman primates, are transmitted through direct contact of bodily fluids with infected individuals resulting in death up to 90 percent of the time. Due to its high pathogenicity and its ability to spread by aerosol droplets, EBOV and its sister virus, Marburgvirus, are classified as category A bioterrorism threats. Currently, no licensed vaccines or antivirals are available against EBOV.

In a previous study the researchers developed a replication-deficient, biologically contained EBOV, EbolaδVP30, vaccine candidate which lacks the essential VP30 gene. In this study they demonstrated its safety in STAT-1 knockout-mice and evaluated its protective efficacy in mice and guinea pigs. Results showed that mice receiving two inoculations with EbolaδVP30 were protected against lethal infection with a mouse-adapted EBOV and viral levels in the blood of vaccinated mice were noticeably lower that those in nonvaccinated mice. Additionally, guinea pigs immunized twice with EbolaδVP30 were also protected against lethal infection with a guinea pig adapted EBOV.

"Our study demonstrates the potential of the EbolaδVP30 virus as a new vaccine platform," say the researchers. "As with other EBOV vaccine candidates, our vaccine would be of value to health care personnel, laboratory workers, and military personnel, as well as those at risk during outbreaks."

Reference: P. Halfmann, H. Ebihara, A. Marzi, Y. Hatta, S. Watanabe, M. Suresh, G. Neumann, H. Feldmann, Y. Kawaoka. 2009. Replication-deficient Ebolavirus as a vaccine candidate. Journal of Virology, 83. 8: 3810-3815.