Scientists at the Walter Reed Army Research Institute and the Naval Medical Research Center have created a new messenger RNA vaccine against malaria, a common infectious disease that killed nearly half a million people in 2019. This is reported in an article published in the journal Vaccines.
Currently, the most modern vaccine is RTS, S, which is based on the circumsporozoite protein (CSP) secreted at the sporozoite stage of the life cycle of Plasmodium falciparum. The vaccine protein itself is recombinant, that is, it consists of two parts – that part of the CSP that is recognized by immune T cells and the envelope protein of the hepatitis B virus to enhance the immune response. However, it has limited effectiveness and duration of protection against malaria.
The new vaccine is also based on CSP, but in this case the recombinant protein is not injected directly. Instead, messenger RNA (mRNA), which encodes a CSP protein and is surrounded by a lipid envelope, enters the body. This nanoparticle protects mRNA from premature destruction. As experiments in vitro have shown, getting inside cells during transfection (a non-viral method of introducing nucleic acid), mRNA causes cells to independently synthesize a circumsporozoite protein, which triggers the immune system, but does not cause infection.
Testing in a mouse model has shown that the RNA vaccine provides a high level of protection of animals against infection with two strains of P. berghei transgenic parasites. In the future, scientists plan to move on to clinical trials of the drug.
