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

Alphaviruses pose significant risks to warfighters where encephalitic virus infection can lead to death. There is no effective treatment foralphavirus induced encephalitis and countermeasures are of high importance. Single domain antibodies (sdAb) are low molecular weightengineered antibody fragments composed of a single heavy-chain variable domain which have proven easier to manipulate and re-engineerthan full-length antibodies because of their small size and well described structure. sdAbs are able to access small protein epitopes that largerantibodies cannot bind because of steric hindrances. There have been numerous studies describing sdAbs capable of crossing the blood brainbarrier (BBB) or neutralizing bacterial toxins or viruses, however no sdAbs have been described with both functions. This SBIR Phase II projectseems to build upon our Phase I results by selecting neutralizing single domain antibodies against WEEV and EEEV. We will prove sdAbmanufacturing feasibility on the pilot-scale using high cell density fermentation. Single-domain antibodies against VEEV will be tested against alethal dose of virus in a mouse model to prove their potential as a medical countermeasure. Additional studies will consist of a trigger to treatinvestigation and neutralization of EEE and WEE viruses.