From bench to almost bedside: the long road to a licensed Ebola virus vaccine

Abstract

Introduction: The Ebola virus (EBOV) disease epidemic during 2014-16 in West Africa has accelerated the clinical development of several vaccine candidates that have demonstrated efficacy in the gold standard nonhuman primate (NHP) model, namely cynomolgus macaques.

Areas covered: This review discusses the pre-clinical research and if available, clinical evaluation of the currently available EBOV vaccine candidates, while emphasizing the translatability of pre-clinical data generated in the NHP model to clinical data in humans.

Expert opinion: Despite the existence of many successful EBOV vaccine candidates in the pre-clinical stages, only two platforms became the focus of Phase 2/3 efficacy trials in Liberia, Sierra Leone, and Guinea near the peak of the epidemic: the Vesicular stomatitis virus (VSV)-vectored vaccine and the chimpanzee adenovirus type 3 (ChAd3)-vectored vaccine. The results of three distinct clinical trials involving these candidates may soon pave the way for a licensed, safe and efficacious EBOV vaccine to help combat future epidemics.

Keywords: Clinical trials; ebola virus; nonhuman primates; vaccines.

Figure 1. Structure and design of vaccine vectors against EBOV

A) DNA- or Ad5-vectored vaccines, B) Ad26/Ad35-vectored vaccines, C) ChAd3-vectored vaccines with MVA-vectored boost, D) VSV-vectored vaccines, E) EBOV-VLPs, F) HPIV3-vectored vaccines, G) VEEV-vectored vaccines, H) RABV-vectored vaccines, I) EBOVΔVP30 vaccine and J) CMV-vectored vaccine.