The Lancet medical journal reports promising initial results from a groundbreaking Ebola vaccine trial in an African population. Two experimental DNA vaccines, designed to prevent Ebola and the closely related Marburg virus (both belonging to the Filoviridae virus family), demonstrated a significant immune response in healthy Ugandan adults.
“This is the first study to show comparable safety and immune response of an experimental Ebola vaccine in an African population,” said lead author Dr. Julie Ledgerwood from the National Institutes of Allergy and Infectious Diseases (NIAID) at the National Institutes of Health, USA. “This is particularly encouraging because those at greatest risk of Ebola live primarily in Africa, and diminished vaccine protection in African populations has been seen for other diseases.”
To date, the Ebola virus has caused the deaths of over 6.900 people, mostly hailing from Sierra Leone, Liberia and Guinea. Despite the urgency of the situation, no effective preventative measure has been yet discovered, although a few clinical trials are currently underway.
The research team tested their new vaccine, designed to code for Ebola virus proteins from the Zaire and Sudan strains (which are the ones responsible for the outbreak in Africa), on 108 healthy individuals from Kampala, Uganda. Each volunteer, recruited between November 2009 and April 2010, was randomly assigned to receive Ebola vaccine, Marburg vaccine, both vaccines, or a placebo at the beginning of the trial and again 4 and 8 weeks later.
Analysis of the collected data showed that the Ebola and Marburg vaccines, whether given separately or in conjunction, were safe (only one adverse reaction was observed) and effective at eliciting an immune response by neutralising antibodies and T-cells against the virus proteins. More than half of the participants showed an antibody response to the Ebola Zaire protein, but were back to baseline within 11 months.
“These findings have already formed the basis of a more potent vaccine, delivered using a harmless chimpanzee cold virus, which is undergoing trials in the USA, UK, Mali, and Uganda in response to the ongoing Ebola virus outbreak.” said Dr. Ledgerwood.
In an editorial, linked with the study, Dr. Saranya Sridhar from the Jenner Institute at the University of Oxford, UK, noted that this trial should serve as an axis for Ebola vaccine development.
“The international response to the present Ebola outbreak is an exemplar of the speed and purpose with which clinical vaccine development can progress and has set the benchmark against which future vaccine development must be judged.
This study is the first step on the aspirational road toward the deployment of filovirus vaccines in Africa and must serve to shake the metaphorical cobwebs that can stall our advance toward this destination.”