Herpesvirus CMV-based vaccine shown to be effective against Ebola

Researchers have shown the ability of a vaccine vector based on a common herpesvirus called cytomegalovirus (CMV) expressing Ebola virus glycoprotein (GP) to provide protection against Ebola virus in the experimental rhesus macaque, non-human primate (NHP) model.

Demonstration of protection in the NHP model is regarded as a critical step before translation of Ebola virus vaccines into humans and other great apes.

In addition to establishing the potential for CMV-based vaccines against Ebola virus, the researchers say these results are exciting from the potential insight they give into the mechanism of protection. Herpesvirus-based vaccines can theoretically be made to produce their targeted protein (in this case, Ebola virus GP) at different times following vaccination. The current CMV vaccine was designed to make the Ebola virus GP at later times. This resulted in the surprising production of high levels of antibodies against Ebola virus with no detectable Ebola-specific T-cells. This immunological shift towards antibodies has never been seen before for such primate herpesvirus-based vaccines, where responses are always associated with large T-cell responses and poor to no antibodies.

Biasing immunity towards antibodies or T-cells

“This finding was complete serendipity,” says Dr Michael Jarvis who is leading the project at Plymouth University. “Although we will definitely need to explore this finding further, it suggests that we may be able to bias immunity towards either antibodies or T-cells based on the time of target antigen production. This is exciting not just for Ebola, but for vaccination against other infectious as well as non-infectious diseases”.

The current study is a step forward, not only for conventional Ebola virus vaccines for use in humans, but also in the development of ‘self-disseminating vaccines’ to target Ebola in great apes, and other emerging infectious diseases in their wild animal host before they fully establish themselves in humans.