Washington:
The first needle-free Ebola vaccine that can be inhaled protects non-human primates against the deadly virus and may advance to human clinical trials soon, scientists say.
Aerosolised delivery has never before been tested for an Ebola vaccine or any other viral hemorrhagic fever vaccine.
The new vaccine was developed by a collaborative team from The University of Texas Medical Branch at Galveston (UTMB) and the US National Institutes of Health.
Previous studies with primates suggest that aerosols of most biothreat agents, which are particles dispersed in the air, are infectious.
Recent studies show that contact with the Ebola virus through the mucus membranes that line the respiratory tract results in infection, suggesting that airway linings may be important portals of entry for the virus.
"A needle-free, inhalable vaccine against Ebola presents certain advantages. Immunisation will not require trained medical personnel," said lead author Michelle Meyer, postdoctoral fellow at UTMB.
The study characterised the immune responses generated by vaccination against Ebola delivered to the respiratory tract of rhesus macaques as either an aerosol or liquid. Direct comparisons were made with an unrelated protective injectable Ebola vaccine.
This included detailed comparisons between immune T cell responses in the lungs, spleen and blood.
A single vaccination with the aerosol developed by the researchers protected non-human primates against the severe disease and death caused by lethal Ebola infection.
"This study demonstrates successful aerosol vaccination against a viral hemorrhagic fever for the first time," said senior author Alex Bukreyev, a professor at UTMB.
"A single-dose aerosol vaccine would enable both prevention and containment of Ebola infections, in a natural outbreak setting where healthcare infrastructure is lacking or during bioterrorism and biological warfare scenarios," Mr Bukreyev said.
The findings of this study provide the basis for advancing this experimental vaccine to an NIH phase I clinical study.
Pending approval through an Investigative New Drug Application, the aerosolised form of the vaccine will be evaluated for replication, safety and immunity development in a study in adults, researchers said.
The study was published in the Journal of Clinical Investigation.