mRNA Vaccine Shows Protection Against Three Ebola Strains in Mice

A new mRNA vaccine has been developed that may provide long-term protection against three strains of Ebola virus, including the Bundibugyo strain currently spreading in two African countries. Health officials are working to tackle Bundibugyo virus in the Democratic Republic of the Congo.

Over 600 people are thought to have been infected with Bundibugyo virus in the Democratic Republic of the Congo and there have been two confirmed cases in Uganda, leading the World Health Organization to declare the outbreak a public health emergency of international concern.

Yao at the Wuhan Institute of Virology in China and his colleagues developed a vaccine that works in mice to protect against all three viruses. The researchers combined the mRNA encoding the glycoproteins of each virus as well as the shared nucleoprotein inside a single lipid nanoparticle.

Mice were administered the vaccine and monitored to see if their immune system responded, before being exposed to all three viruses. All immunised animals gained complete protection against infection by the Zaire and Sudan viruses and were conferred strong protection from Bundibugyo.

Hamsters exposed to Sudan virus were also afforded complete protection by the vaccine.

The researchers caution that the vaccine has only been tested on rodents so far, and more work is needed to show it is safe and effective in humans. Robert Cross at the University of Texas Medical Branch says testing in non-human primates is the gold standard for predicting efficacy in humans.

Adrian Esterman at Adelaide University in Australia says it is a promising preclinical study, but a limitation is that the findings only apply to rodents. He says moving from this stage to human trials would usually take several years because further animal work, manufacturing development and safety testing are still needed.