Could an mRNA vaccine be protective against emerging tick-borne viruses?


An mRNA-based vaccine is effective at preventing Powassan virus in mouse models, according to new research. In addition, the team demonstrated that the vaccine elicited cross-reactive, neutralizing antibodies that can protect mice against related tick-borne flaviviruses.

Powassan virus is an tick-borne virus that can cause encephalitis in humans – although it is rare, circulating in North America and Russia, it can be life threatening and currently has no known prevention or treatment. Moreover, it is considered as emerging with increasing numbers of cases diagnosed in the USA over the past decade.

This study, published recently in Cell Reports, investigated a new vaccine for Powassan virus composed of viral mRNA encapsulated in lipid nanoparticles. This composition produces subviral particles that produce an immune response and elicit protection.

The vaccine was assessed in mice, proving effective against two different strains of Powassan virus after just one dose. Moreover, the vaccine was also offered protection against the more distantly related Langat virus as a result of cross-reactive, neutralizing antibodies.

The team suggest this vaccine platform could also be used to produce candidates for other flaviviruses. Lead author Michael Diamond (Washington University School of Medicine in St. Louis, MO, USA) concluded: “We are excited that this mRNA-based vaccine against Powassan virus was highly immunogenic and conferred protection against multiple members of the family. We plan to continue studying the molecular basis for its broadly neutralizing antibody activity and test the vaccine against additional related viruses.”

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Source: VanBlargan LA, Himansu S, Foreman BM, Ebel GD, Pierson TC, Diamond MS. An mRNA vaccine protects mice against multiple tick-transmitted flavivirus infections. Cell Rep. 25, 1–11 (2018);


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