mRNA Vaccines Against Tick‐borne Diseases

Vector-borne diseases that account for more than 700 000 deaths annually are carried by arthropods that spread viruses, bacteria, and parasites. Effective vaccines are needed for most of the diseases spread by mosquitoes, ticks, sandflies, and other vectors. Since pathogens that live in arthropods for part of their life cycle adapt to different conditions and often do not rely upon a single virulence effector for pathogenesis, it is harder to develop vaccines with long-lasting protection. The increasing cost of development, clinical trials, and deployment are additional obstacles to the generation of effective protective measures. This can be partially solved by mRNA vaccines that can be produced on a large scale, in quick turnover time, and in a cost-efficient manner. Modified mRNA vaccines, combined with lipid nanoparticles or another strong adjuvant, can help induce the immune system to develop an effective memory response. Furthermore, this vaccine platform allows multiple antigens to be targeted simultaneously. Recent discoveries in mRNA vaccines against tick-borne diseases also shift the paradigm from developing therapies that neutralize pathogens to those that target the vector. Among tick-borne diseases, three mRNA vaccines – two targeting Powassan virus or Crimean–Congo hemorrhagic fever and a third multiantigen mRNA vaccine that specifically targets Ixodes scapularis ticks to prevent Lyme disease, are being developed. In this chapter, we will discuss the recent advances in mRNA-based vaccines against tick-borne diseases.