Breakthrough For Vaccine Delivery
[ The University of Melbourne Voice Vol. 3, No. 9
10 November - 8 December 2008 ] By Nerissa Hannink
Delivering flu vaccine directly into the lungs can trigger a greater immune response than conventional injections, according to University of Melbourne research.
The finding raises the possibility of existing flu vaccine stocks being used to treat far greater numbers of people in a pandemic, despite an expected extreme global shortage of vaccines.
The research showed that delivering into the lungs a very small dose of vaccine with an adjuvant – a substance added to a vaccine to boost the immune response – produced the same level of blood antibodies as an injection of a much larger amount.
Research leader Associate Professor Phil Sutton, of the University’s Centre for Animal Biotechnology (CAB), says that one of the biggest problems the world would face in the event of a human pandemic flu outbreak would be to produce enough vaccine in time to protect the global population.
“Our results suggest that delivery via the lung may allow a much lower amount of vaccine antigen to be used, while inducing equivalent or perhaps even improved protection. This would mean more people would quickly be able to receive the vaccine, he says.”
The research, published in the journal Mucosal Immunity, was conducted in sheep. It showed that delivering the vaccine into the lung – where the influenza virus infects – produced approximately 1000 times as many antibodies in the lung than injecting the vaccine.
The results of the study surprised even the scientists carrying it out, according to Associate Professor Sutton.
“When we did the first lung vaccination we were simply aiming to compare 15 micrograms [millionths of a gram] injected versus 15 micrograms via the lung with adjuvant,” he said.
“We thought the addition of adjuvant might allow some antigen reduction so we tested down to one microgram and this was so effective we ended up having to perform further studies.”
The researchers were able to determine that they could induce strong responses with as little as 0.04 micrograms – 375 times less antigen than was required when injecting.
Associate Professor Sutton says the generation of functional antibodies in the lung could potentially also help reduce the spread of the infection by neutralising the virus before it can be breathed out by an infected person.
The project has involved six years of research by a CAB team (based in the Faculty of Veterinary Science) which includes Dr Janet Wee, Associate Professor Jean-Pierre Scheerlinck and Dr Ken Snibson.
Associate Professor Sutton says their next major challenges are to explore technologies for efficient delivery of the vaccine to humans by aerosol and validate the findings in clinical studies.
Know your enemy: Electron microscopy image (top) of influenza virus purified by Alex Courtney, a BSc Hons student working with Professor Lorena Brown (Microbiology and Immunology). Images captured by Dr Simon Crawford in the School of Botany Electron Microscope Unit.
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