A more affordable, lower-risk vaccine could soon be possible following research conducted at Diamond’s electron Bio-Imaging Centre (eBIC).
Scientists have made significant progress in developing a more cost-effective and safer polio vaccine, something which is essential for the global effort to eliminate the disease. Polioviruses mainly affect children under five years of age, with some infections leading to irreversible paralysis and sometimes death.
For the last three decades, the World Health Organization, which funded the study, has been focused on the worldwide eradication of polio. Since 1988, poliovirus cases have decreased by 99% and the possibility of eliminating this disease is on the horizon. The prospect of a new type of vaccine could play a significant part in this endeavour.
The research project looked at using virus-like particles (VLPs). These particles imitate the outer protein structure of the poliovirus but are hollow inside and do not contain any viral genetic material. This eliminates the risk of infection while still triggering an immune response.
Researchers from the University of Leeds have been exploring how different types of cells – yeast, mammalian and plant cells – can be used to produce VLPs. Their findings, recently published in Nature, indicate that VLPs generated in yeast and insect cells can perform equally or better than the currently used inactivated polio vaccine (IPV).
Peijun Zhang, director of eBIC, said:
Cryo-EM at eBIC enables scientists to determine the detailed 3D structure of VLPs, revealing how they resemble real viruses in shape and protein arrangement. This helps researchers optimise the design of VLP-based vaccines to ensure they trigger a strong immune response while remaining non-infectious.
The current polio vaccine (IPV) is relatively expensive to use as it requires a high level of biocontainment to minimise the risk of leaks of the live polio virus, which could lead to outbreaks. In contrast, the VLP simulated particles are non-infectious, therefore removing the need for bio-safety protocols.
Professor Nicola Stonehouse, of the University of Leeds School of Molecular and Cellular Biology and one of the senior authors on the paper, said: “Any vaccine is only as effective as the number of children that it reaches. The key is to make vaccines universally accessible, as all children have a right to be protected from diseases such as polio, no matter where they live. VLPs would significantly contribute to vaccine equity.”
The plan to eradicate polio
The oral polio vaccine (OPV) contains a weakened vaccine-virus and its continued use could hinder the complete eradication of the disease. Once all strains of wild poliovirus strains are eradicated, the use of OPV will be phased out. This is because the weakened form of the virus in the OPV can sometimes mutate and cause variant forms. When the use of the OPV stops, the IPV will be the only available vaccine. However, its expensive manufacturing procedure make it unaffordable for lower-income countries, possibly leading to a reduction in vaccination rates.
The virus-like particle (VLP) vaccines are the promising alternative, as with no viral genetic material, they are non-infectious and safer than traditional vaccines. They can also be engineered to be more stable, which maintains their effectiveness during storage or transportation.
This could eventually lead to a more equitable access to vaccination, ensuring that countries that do not have suitable infrastructure can safely store and distribute the vaccine.
VLP vaccines have already been successfully used for other diseases, like hepatitis B and human papillomavirus (HPV), and researchers have been working for over a decade to successfully apply this technology to help eradicate polio.
The international research collaboration includes researchers from the University of Oxford, the Medicines and Healthcare products Regulatory Agency (MHRA), the John Innes Centre, the Pirbright Institute, the University of Florida and the University of Reading. All of the cryo-EM data was collected at eBIC.
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