Sweet technique could keep virus vaccines cool
'Glass' layers made from sugar can preserve potential HIV, TB and malaria vaccines without the need for refrigeration, researchers have found.
In research published in Science Translational Medicine today (17 February) a team of scientists in the United Kingdom preserved model live virus vaccines by exploiting a natural process called anhydrobiosis, where organisms survive in suspended animation within sugars that can be dried to form 'glass'.
Scientists hope this could eliminate the need for a cold chain in which vaccines must be kept refrigerated from production through to injection — a difficult task for some developing countries.
The technique has previously been used by the same company to make protein vaccines heat stable by preserving them within sugar beads (see Zero refrigeration vaccine trials to begin).
Building on this work, the scientists have been able to trap model live virus vaccines — which are much harder to make heat stable — on filters within a glass film made of sugars. The 'vaccines' survived for six months at temperatures of up to 45 degrees Celsius.
The researchers say such vaccines could be reconstituted at point of use by dissolving the sugar with a buffer solution from a syringe and injecting the whole solution into the patient. The technique is yet to be tested in humans.
The model vaccines used were similar to those being developed for HIV, TB and malaria, which use live modified viruses to carry the active part of a vaccine.
The researchers replaced this active part with a fluorescent tag so the vaccines could be easily observed during the experiments. But Matthew Cottingham, a senior virologist at Oxford University and co-author of the study, said that real vaccines should behave in an identical way.
"We hope [the new vaccines and our technology] will come together at roughly the same time so we can have efficacious virus vaccines that we can deploy using [the technique]," he said.
"The development of a process that would allow us to move away from cold chain as a means of storing and transporting vaccines would be a major breakthrough," Christian Loucq, director of the PATH Malaria Vaccine Initiative told SciDev.Net.
However, Ian Jones, professor of virology at Reading University, United Kingdom, cautioned that although the model vaccines used in the research are currently in clinical trials, they are not yet part of a vaccine licensed for human use.
But, "assuming some do become products, even if only in very special cases, this technology ought to maximise their usefulness as long as the costs are acceptable," he said.