Aerosol vaccines could make a jab-free future

Dr Anushi Rajapaksa

Researchers have developed a potential alternative for needle vaccinations, successfully trialing a method in which people can inhale a vaccine to be safeguarded against potential infections.

A team of researchers at Murdoch Childrens Research Institute and Monash University developed a novel way of turning a liquid vaccination into an aerosol form against the flu. In a world-first study, the researchers used a plasmid DNA vaccine and came up with a novel way of aerosolising sensitive biomolecules via the use of very small but powerful sound waves.

In the study researchers used this technology to provide a strong immune system after inhalation of the DNA vaccine in sheep - a useful pre-clinical model as they have similar lung structure and physiology to humans. The study showed that there were protective antibodies in the sheep's blood, at a level considered significant by the World Health Organisation.

The nebulizer device, which is no bigger than a matchbox, is already in mobile phones but researchers discovered a new use for it. They found that when they applied electricity to the device a miniature sound wave travels on the surface of the device. This wave interacts with the medication to agitate it so much so that the surface tension of the fluid is broken up to form a fine mist of particles. The timing of these events happens so fast that the DNA molecules in solutions have no time to stretch and so there is little to no damage to their structure.

Lead researcher, Dr Anushi Rajapaksa said this development holds a lot of promise for a replacement to vaccine injections which are associated with safety concerns in developing countries, requiring expensive and specialised handling, refrigeration, and staff training that many places in the world cannot afford.

"Current vaccines often induce inflammation, causing pain, requiring monitoring by health care workers and resulting in peoples' unwillingness to seek vaccination. We sought to re-engineer vaccine administration with our respiratory nebuliser for plasmid DNA vaccine delivery. A DNA-based vaccine can be produced in as little as two weeks, a critically important improvement in the face of a pandemic."

"The nebulizer technology can be made portable and only requires batteries for operation. There is huge potential of this work to be used for mass vaccination programs especially in the developing countries with limited resources."

The nebulizer works as droplets containing the vaccine are inhaled and deposited on the surfaces of the lung. Once the DNA of the vaccine is introduced into a person's cells those cells produce "antigen" proteins. The immune system is trained to attack the disease by producing antibodies against these antigen
proteins. There is no inflammation when using DNA vaccines, and no use for needles for injection, making it much easier for a person to tolerate.

Inhaled immunisation using the nebuliser is especially suitable for lung-related afflictions such as influenza, and, potentially for treatment of systemic diseases such as Malaria with entirely new DNA vaccines.

This research was done in collaboration with Professor James Friend, Professor Leslie Yeo, Professor Els Meeusen, Dr. Michelle McIntosh, Professor Ross Coppel Dr. Aisha Qi, Dr. Jenny Ho, Dr. Rob Bischof, Dr. Tri-Hung Nguyen, Dr. Michelle Tate and Associate Professor David Piedrafita.