A vaccine would not only reduce Ebola transmission from person to person in an ongoing epidemic, but it would also help control further outbreaks.
In trials with non-human primates, a single inhaled dose of the experimental vaccine, successfully gave the animals long-term protection against lethal Ebola infection.
Results of the pre-clinical study are reported in the journal Molecular Pharmaceutics. It is thought to be the only proof to date that a single, non-injected dose of anti-Ebola vaccine can give long-lasting protection.
Co-author Maria A. Croyle, a professor in the College of Pharmacy at the University of Texas at Austin, is to present the study findings on 5th November at the 2014 American Association of Pharmaceutical Scientists (AAPS) Annual Meeting and Exposition.
She and her group worked with a team at the National Microbiology Laboratory in Winnipeg led by co-author Dr. Gary Kobinger.
Inhalable vaccine could overcome many of the obstacles faced by immunization campaigns
Should it work in humans, the breathable vaccine they are working on could make a significant contribution to controlling future outbreaks of the deadly virus.
The ease with which vaccines can be shipped, stored and administered plays an important part in successful immunization campaigns, especially where health systems and infrastructures are patchy. An inhalable vaccine can overcome many of these obstacles.
Depending on the strain, the Ebola virus kills between 25% and 90% of the people it infects and causes devastating outbreaks in Africa and Asia. While scientists are making great progress toward understanding the biology of the virus, as yet, there are no licensed treatments or vaccines.
The current epidemic of Ebola in West Africa - where around 70% of cases are fatal - is the largest and most complex the world has ever seen since the virus was discovered in 1976. The World Health Organization (WHO) have declared it a public health emergency of international concern.
A vaccine would not only reduce transmission from person to person in an ongoing epidemic, but it would also help control further outbreaks.
The inhalable Ebola vaccine improved survival in non-human primates
Prof. Croyle and colleagues have been developing an inhalable form of an Ebola vaccine for over 7 years. They carried out trials of it in non-human primates and found it improved survival of immunized animals from 67% to 100% when the animals were infected with 1,000 plaque-forming units of Ebola 150 days after immunization. The strain used was the Zaire strain - the one currently circulating in West Africa.
The authors note: "The formulated vaccine was fully protective against challenge 21 weeks after immunization."
When the animals were given the vaccine by the standard method of intramuscular injection, only 50% survived the infection challenge.
Prof. Croyle says the main advantage of their vaccine over others currently undergoing clinical testing is that it offers long-lasting protection after a single inhaled dose, and explains:
"This is important since the longevity of other vaccines for Ebola that are currently being evaluated is not fully evaluated. Moreover, this immunization method is more attractive than an injectable vaccine given the costs associated with syringe distribution and needle safety and disposal."
She and her team are now planning phase 1 clinical trials in humans. They are also continuing to analyze data they collected from non-human primate trials that tested the vaccine given as a thin film under the tongue.
A grant from the National Institutes of Health helped fund the study.
Medical News Today recently learned of another study that suggests surviving or dying from Ebola may be partly down to genes. The researchers hope that the strains of lab mice they bred for the study will help speed up the development of anti-Ebola treatments and vaccines.