Ebola virus vaccines: an overview of current approaches

Abstract

Ebola hemorrhagic fever is one of the most fatal viral diseases worldwide affecting humans and nonhuman primates. Although infections only occur frequently in Central Africa, the virus has the potential to spread globally and is classified as a category A pathogen that could be misused as a bioterrorism agent. As of today there is no vaccine or treatment licensed to counteract Ebola virus infections. DNA, subunit and several viral vector approaches, replicating and non-replicating, have been tested as potential vaccine platforms and their protective efficacy has been evaluated in nonhuman primate models for Ebola virus infections, which closely resemble disease progression in humans. Though these vaccine platforms seem to confer protection through different mechanisms, several of them are efficacious against lethal disease in nonhuman primates attesting that vaccination against Ebola virus infections is feasible.

Keywords::

• animal model
• Ebola virus
• filovirus
• prophylaxis
• vaccine

Acknowledgements

The authors would like to thank Austin Athman (Rocky Mountain Laboratories, NIAID) for assistance with production of Figure 1 .

Financial & competing interests disclosure

Ebola virus research is supported in part by the Division of Intramural Research, National Institute of Allergy and Infectious Diseases, NIH. H Feldmann claims intellectual property regarding the vesicular stomatitis virus-based filovirus vaccines. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Ebola viruses cause sporadic outbreaks of hemorrhagic fever in Central Africa with increasing frequency and high case fatality rates.

• There are no approved vaccines or treatment strategies available, making efforts toward effective prophylaxis and therapeutics urgent.

• Several experimental vaccine approaches have shown promising protective efficacy in nonhuman primate models of Ebola hemorrhagic fever [rec. vesicular stomatitis virus (rVSV), rec Adenovirus 5 (rAd5), virus-like particles, rec. rabies virus (rRABV)], but development has not progressed past Phase I Clinical Trials.

• While antibodies have been shown to be a mechanism of protection for the rhabdovirus-based vaccine vectors (rRABV and rVSV), protective efficacy with the rAd5 platform seems to be dependent on CD8⁺ T cell and antibody responses.

• The development of various vaccine platforms is encouraged as they have their advantages/disadvantages for distinct application approaches.

Notes