Abstract
The influenza virus infection claims ~650,000 lives annually. Taking into account the evolving resistance of the pathogen to antiviral drugs and the waning effectiveness of vaccination among certain populations, new approaches to the treatment of influenza are needed. The current study is aimed at obtaining single-domain antibodies (Nanobodies®) to the highly conserved stem domain of influenza A virus hemagglutinin by phage display. Two high-affinity neutralizing clones of Nanobodies® with a particular specificity were selected; they ensured 100% neutralization of the H1N1 and H5N2 influenza viruses in vivo. The obtained data demonstrate that it is possible to develop highly effective VHH-based drugs for the treatment of influenza.