Cross-Protective Multivalent Vaccine for Tick-Borne Flaviviruses

Project Summary/AbstractThe NIH/NIAID 2017 Strategic Plan is specifically directed at promoting research that can provide
solutions to mitigate the threat posed by emerging and re-emerging diseases. The tick-borne flavivirus
(TBFV) group includes a number of important human pathogens that result in serious neurological or
hemorrhagic diseases that are either Category B or C priority pathogens. The TBFVs are considered to be
emerging or re-emerging pathogens due to increases in the number of human infections, the expansion of
their geographic distribution, and emergence of new viruses. Additionally, the number of different viruses in
the TBFV group poses challenges. There are two licensed Tick-borne encephalitis virus (TBEV) vaccines in
Europe. These vaccines are based on the European strains of TBEV (TBEV-Eu), and while they provide
some level of cross-neutralization, not all of the TBFV are covered. Furthermore, these vaccines are not
licensed in the U.S. and are no longer available in Canada. The development of a multivalent vaccine that
provides cross-protection against multiple pathogenic TBFVs would be of great value and is in line with the
priorities of NIH/NIAID to develop multivalent and cross-protective technologies. We have demonstrated
that two combinations of TBFV recombinant envelope subunit proteins (r80E) can provide protection against
a diverse range of TBFV in a mouse challenge model. Additionally, passive transfer studies using serum
from mice immunized with combinations of the r80E protein confirm the role of antibodies in protection
against virus challenge. This Phase IIB application builds upon our initial efforts to develop a multivalent
TBFV vaccine that provides broad cross-protection against viruses in this group. The proposed research
aims to 1) optimizing the vaccine formulation; 2) produce pilot lots of the antigens; 3) conduct a pre-IND
meeting with the FDA; and 4) conduct potency and toxicity testing to establish the suitability and safety of
the final TBFV vaccine formulation. With the successful completion of these efforts, we will be positioned to
advance a multicomponent TBFV vaccine into a cGMP manufacturing campaign and toward clinical
evaluation.Project Narrative
The proposed research is focused on developing a candidate vaccine that protects against a family of
related viruses in the tick-borne flavivirus (TBFV) group which causes disease in humans. The vaccine
candidate would be a single multivalent vaccine that would provide protection against many viruses in the
TBFV group. The approach is based on a technology to produce vaccine components comprised of
recombinant subunit envelope proteins. Although TBFVs are normally found outside the U.S. they are
identified as priority pathogens, so a multivalent vaccine would help meet the mission of providing
protection for U.S. citizens against several priority pathogens with a single vaccine. Such a multivalent
TBFV vaccine can be utilized to protect military and state department personnel, first responders, and U.S.
TBFV virus researchers who are currently forced to go abroad for vaccination, in addition to travelers or
people at risk in endemic areas.