Vaccine production can be hazardous for those involved in the production process, forcing manufacturers to work in a strictly controlled environment to ensure pathogens don’t escape.
However, writing in the journal PLOS Pathogens, scientists from Oxford and Reading Universities, the Pirbright Institute, and the UK’s national synchrotron facility, the Diamond Light Source near Oxford, revealed a prototype vaccine that does not use a live virus. As such, scientists have created a synthetic vaccine for foot-and-mouth disease, which they claim to be more stable than traditional vaccines.
The vaccine’s increased stability could mean that it can be kept out of the fridge for longer than a standard vaccine, before the need to return it to chilled storage. This, scientists have said, could be key to overcoming a major hurdle in the administration of vaccines in the developing world.
Major plague of livestock
Scientists said foot-and-mouth disease remained a major plague of livestock, with regular and often economically catastrophic outbreaks. They explained that current and inactivated virus vaccines required expensive high-containment facilities for their production and maintenance of the cold chain storage activity.
Also, according to the scientists, vaccination is currently reliant on the use of inactivated viruses produced in large bioreactors in high-containment facilities. They explained this was “unsatisfactory” on several grounds: it was an expensive set-up as well as being expensive to run; there was limited global production capacity; limited storage and supply, due to vaccine stability; and it was difficult to distinguish between vaccinated and infected animals.
“We have addressed these major drawbacks,” they said. “Firstly we have developed methods to efficiently express recombinant empty capsids. Expression constructs were used, aimed at lowering the levels and activity of the viral protease required for the cleavage of the capsid protein precursor.”
Scientists also said they had enhanced capsid stability by incorporating a “rationally designed mutation”, which is shown by X-ray crystallography and stabilises the wild-type empty capsids, which have, essentially, the same structure as an intact virus.
“Attempts to produce alternative vaccines have shown that intact virus particles stimulate the best immune response,” the scientists said. However, the synthetic virus replicates the protein structure of a standard vaccine made with a live virus “since the capsid proteins spontaneously assemble to produce empty virus-like-particles”.