Advances in Developing Vaccines for Filoviruses, Including Ebola

Filoviruses, among the most lethal pathogens known, pose significant challenges to global health due to their high mortality rates and limited treatment options. These viruses, including Ebola and Marburg, are classified under the family Filoviridae and are primarily transmitted through zoonotic spillover, often originating from fruit bats, primates, or forest antelopes. Human infections typically result from hunting or butchering bushmeat, emphasizing the importance of understanding their transmission pathways.

Over the past fifty years, scientific efforts have focused on vaccine development. The 2014-2016 West African Ebola outbreak catalyzed the creation of Ervebo, the first FDA- and EMA-approved Ebola vaccine, manufactured by Merck & Co. This vaccine provides targeted protection against Ebola virus, but no licensed vaccines currently protect against other filoviruses like Marburg.

Recent research by a U.S. military institute has examined whether existing Ebola vaccines could offer cross-protection against related filoviruses. Their studies involved testing a recombinant Ebola vaccine that encodes various glycoproteins from multiple filoviruses. Results indicated that while the vaccine elicited strong immune responses specific to Ebola, it showed limited effectiveness against other family members like Marburg or Sudan viruses. Blood sample analyses from survivors of related outbreaks confirmed that the immune responses remained species-specific.

Meanwhile, researchers at the University of Texas are exploring antiviral treatments such as obeldesivir—a pill form of Remdesivir initially developed for COVID-19—that shows promise in curing Ebola-infected primates. The goal across these initiatives is to develop broad-spectrum or multivalent vaccines that can prevent multiple filoviruses, reducing the threat of future outbreaks.

Despite the ancient origins of filoviruses, their discovery occurred mainly in the 20th century, with key outbreaks and vaccine developments occurring in recent decades. The ongoing efforts aim to produce more practical, easy-to-administer vaccines and treatments that can contain outbreaks rapidly and effectively.

As Dr. Thembi Mdluli from Walter Reed Army Institute of Research emphasizes, the focus remains on creating vaccines capable of broader coverage due to the high lethality and socio-economic impact of these viruses. The development of such vaccines is crucial for global health security and outbreak preparedness.