Selection of blood-brain barrier penetrating single domain antibodies as medial countermeasures for viral induced encephalitis

Alphaviruses pose significant risks to warfighters where encephalitic virus infection can lead to death. There is no effective treatment for alphavirus induced encephalitis and countermeasures are of high importance. Single domain antibodies (sdAb) are low molecular weight engineered antibody fragments composed of a single heavy-chain variable domain which have proven easier to manipulate and re-engineer than full-length antibodies because of their small size and well described structure.sdAbs are able to access small protein epitopes that larger antibodies cannot bind because of steric hindrances. There have been numerous studies describing sdAbs capable of crossing the blood brain barrier (BBB) or neutralizing bacterial toxins or viruses, however no sdAbs have been described with both functions. This SBIR Phase I project uses phage display to sdAbs with high binding affinity to alphaviruses that have the ability to cross the BBB and neutralize by binding viral surface proteins. Inclusion of cell penetrating peptide sequences will enhance the sdAbs ability to traverse the BBB. All characterization will be conducted in vitro using proven BBB models and surface plasmon resonance measurements.