Nanobody-Based Bioconjugates as Potent and Broadly Active Inhibitors of HIV Entry

We describe a semisynthetic strategy that unites the versatility of chemical peptide synthesis with the high affinity and specificity of antibody fragments to create conjugates with remarkably potent anti-HIV activity. Using site-selective enzymatic ligation and click chemistry, we assembled nanobody-fusion inhibitor peptide (Nb-FI) conjugates that link synthetic HIV-1 fusion inhibitor peptides to nanobodies targeting host receptors. This modular approach enables variation of Nb-FI linkage geometry, including C-to-C terminal topologies inaccessible by genetic fusion. Selected semisynthetic conjugates exhibit antiviral potencies up to 10,000-fold better than comparator peptides and broad-spectrum activity across diverse HIV strains. Lead semisynthetic conjugates also outperform analogous genetic fusions. These findings underscore the power of combining chemical synthesis, protein engineering, and antibody delivery to leverage proximity effects in blocking viral infection.