A highly potent and broadly accessible bispecific nanobody for the treatment of ebola virus infections.

Ebola virus (EBOV) causes recurring outbreaks, with a case fatality rate of about 40%. Currently approved vaccine and antibody therapies face major limitations, including only modest reductions in mortality and restricted accessibility due to their reliance on injection-based delivery and cold-chain transport and storage. To address these challenges, we developed a bispecific nanobody, Nanosota-EB1/EB2-Fc, composed of two nanobodies (camelid-derived single-domain antibodies, Nanosota-EB1 and Nanosota-EB2) that target distinct epitopes on the EBOV glycoprotein (GP) and are fused to a human Fc domain. Through cooperative contributions from both nanobodies, this bispecific nanobody strongly inhibits GP function and effectively overcomes the virus's decoy mechanism. A single dose provided strong protection in EBOV-infected mice, including when administered at late stages of infection. It was also effective when administered intranasally, offering a needle-free delivery option. Furthermore, its high in vitro stability indicates that it can be deployed without refrigeration. Taken together, this novel bispecific nanobody represents a promising next-generation therapeutic for EBOV, combining high potency with broad accessibility.