A groundbreaking mRNA vaccine has been developed that promises long-term protection against lethal viruses in the Ebola family, including the Bundibugyo strain currently present in two African nations.

Over 600 individuals are suspected to be infected with the Bundibugyo virus in the Democratic Republic of the Congo (DRC), with two confirmed cases in Uganda. The World Health Organization has classified this outbreak as a public health emergency of international concern.

Bundibugyo virus is part of the ortho-Ebolavirus family, which includes the notorious Zaire and Sudan viruses, all known for causing severe health issues in humans.

While Bundibugyo outbreaks are less common than those of the Zaire strain, which infected over 28,000 people from 2014 to 2016, vaccines for Bundibugyo and Sudanese viruses have yet to be developed, despite the Zaire vaccine being approved.

Recently, Yao Yanfeng and his team at the Wuhan Institute of Virology in China reported the successful development of a vaccine that provides protection against all three viruses in animal models.

“The creation of a broad-spectrum vaccine could significantly mitigate outbreaks from multiple ortho-Ebola viruses,” they stated in their recent publication.

The challenge lies in the fact that each Ebola virus has distinct glycoproteins important for infection; however, they all share a common nucleoprotein that encapsulates the virus’s genetic material.

To formulate the new vaccine, Yao and his colleagues combined mRNA coding for each virus’s glycoprotein along with the shared nucleoprotein into a single lipid nanoparticle. These lipid nanoparticles protect the mRNA vaccines until they reach the targeted cells in the body.

After inoculating the mice with the vaccine, the researchers monitored their immune responses and subsequently exposed them to all three viruses. All immunized mice were fully protected against the Zaire and Sudan viruses and showed robust protection against Bundibugyo. Even hamsters infected with the Sudan virus were completely shielded by the vaccine.

The findings indicate the development of a broad-spectrum mRNA vaccine that effectively protects against the Zaire, Sudan, and Bundibugyo viruses. However, researchers emphasize that further trials are essential to confirm its safety and efficacy in humans.

Robert Cross, a professor at the University of Texas Medical Branch, expressed enthusiasm for the innovative direction of medicine, stating, “Ebola vaccines are under research.”

He cautioned that trials in non-human primates are the gold standard for predicting human efficacy, and gaining regulatory approval for vaccines targeting multiple pathogens is a challenging endeavor.

“Securing approval for a vaccine targeting a single virus is notoriously difficult, and the pathway for a multivalent vaccine is even more complex,” Cross noted.

Adrian Esterman, from the University of Adelaide, remarked that while this preclinical study is promising, its applicability is limited to rodents.

“It’s too early to set a firm timeline for clinical application. Progressing from this stage to human trials typically requires several years, as additional animal studies, including trials with primates, are necessary. Manufacturing processes and safety testing also need to be established,” he commented.