Method offers boost to safety profile of live vaccines

 Scientists have developed a method that could enable large-scale production of an effective flu vaccine for people with health conditions. 

The discovery could help produce industrial quantities of vaccines containing live viruses that have been weakened to induce immunity without causing infection – known as live attenuated viruses.  

These typically enable a speedy, lasting effect against illness, but represent a risk for some groups of people, such as the very young or very old. 

Researchers suggest the development could be used in combination with other methods of attenuation, or weakening, to enhance the safety profile of live virus vaccines. 

Virus recoding 

Researchers at the Roslin Institute developed their version of a vaccine for human flu by amending the virus’ genetic code in the lab.  

They changed letters into the RNA code – single-stranded genetic material – to add specific pairs that are known to make the virus vulnerable to attack from the human immune system. The resulting material contains live virus but will not trigger severe illness. 

Their experimental treatment was tested in mice, which after receiving a vaccine were able to survive exposure to a potentially lethal dose of flu virus. 

Researchers were able to produce large quantities of their vaccine in the growth mediums that are used to propagate live vaccines in industry – chicken eggs and canine kidney cells.  

Their method offers a realistic approach to produce vaccines in a commercially viable way, researchers say.  

It could be adapted to augment the production of existing live attenuated viruses to enhance their safety profile and render them suitable for use in at-risk individuals who currently cannot have vaccines of this type. 

Scientists hope to further investigate the biological processes at work using their method of attenuation, to better understand how the virus behaves and ensure it is used safely. 

The research was published in PLOS Pathogens and supported by the National Avian Research Facility at the Roslin Institute campus. 

Our approach has potential as a vaccine augmentation strategy – this method could be integrated into existing systems to incorporate multiple mechanisms to weaken the live virus contained in vaccines and boost their safety profile. It is a realistic, cost-effective way to amend existing vaccines of this type, for production at scale.

Dr Eleanor Gaunt

** The Roslin Institute receives strategic investment funding from the Biotechnology and Biological Sciences Research Council and it is part of the University of Edinburgh’s Royal (Dick) School of Veterinary Studies. **

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