While our successful peptide vaccine against malaria contains only small protein fragments of the malaria protein, the mRNA vaccine encodes the entire malaria protein
Published Date – 23rd Friday 21st July 06:20 AM
Victoria: In a preclinical model, trans-Tasman research collaborators from Victoria University’s Ferrier Institute at Te Herenga Waka in Wellington, the Malaghan Institute of Medical Research in New Zealand, and the Peter Doherty Institute for Infection and Immunity in Australia developed an mRNA-based vaccine that effectively targets and stimulates a protective immune cell response against the malaria-causing parasite Plasmodium.
Professor Gavin Painter of the Ferrier Institute said the approach was unique because the team drew on years of research by Professor Bill Heath of the University of Melbourne’s Doherty Institute and Professor Ian Hermans of the Malahan Institute.
Professor Painter said that thanks to this synergy, we were able to design and validate an example of an mRNA vaccine that works by generating resident memory cells in the liver of a malaria model.
It demonstrates the enormous potential of RNA technology to address some of the world’s biggest health problems, and the growing capacity and expertise in mRNA vaccine development in New Zealand and Australia. Collaborative research to investigate new targets for malaria is initially focused on peptide-based vaccines. In 2018, however, the team changed approach and began working on RNA-based vaccines, a decision that appears to have paid off with the recent success of RNA technology in vaccine development.
Dr Lauren Holz from the University of Melbourne, a research officer at the Doherty Institute and co-author of the paper, said that while our successful peptide vaccine against malaria contained only small protein fragments of the malaria protein, the mRNA vaccine encoded the entire malaria protein.
This is a real advantage because it means we can generate a broader and hopefully more protective immune response. To provide additional protection, the mRNA vaccine was combined with an adjuvant originally developed at the Malaghan and Ferrier Institute for cancer immunotherapy that targets and stimulates liver-specific immune cells. This additional component helps target the RNA vaccine response to the liver, a key site in preventing the parasite from developing and maturing in the body.
When the parasite first enters the bloodstream, it travels to the liver, where it develops and matures, and then goes on to infect blood cells, at which point disease symptoms appear, said study co-author Dr. Mitch Ganley, a Ferrier Institute postdoctoral fellow.
Unlike COVID-19 vaccines, which work through neutralizing antibodies, our unique approach relies on T cells, which play a key role in immunity. Specifically, a type of T cell called tissue-resident memory T cells blocked malaria infection in the liver, preventing the spread of the infection altogether. Dr. Holz said the main advantage of the vaccine is that it is not affected by previous exposure to malaria.
Many of the malaria vaccines being tested work very well in animal models or when given to people who have not had malaria before, but not as well when given to people living in malaria-endemic areas. In contrast, our vaccine was still able to generate protective liver-specific immune cells, conferring protection even when animal models had been pre-exposed to the disease, Dr. Holz said.
The research team is currently working on putting the vaccine into human clinical trials, which is expected to take several years.
