CH65

Antibodies (Abs) are regarded as a newly emerging form of therapeutics that can provide passive protection against influenza. Although the application of genomics in clinics has increased dramatically, the number of therapeutics available for the treatment of many diseases remains insufficient. To translate genomics into medicines, we established a computational workflow to reconstruct 3D structures of hemagglutinin [HA, antigen (Ag)] and Ab for modeling Ab-HA interactions, based on their protein sequences. This platform was capable of testing the validity of bioinformatics predictions against viral neutralization titers for four Abs: CH65, CR8020, C05, and 5J8. By considering off-target effects, CR8020, the only successful candidate in clinical trials, was prospectively identified. Our approach could facilitate the discovery of Ab drugs against infectious diseases.

Influenza viruses remain a persistent challenge to human health owing to their inherent ability to evade the immune response by antigenic drift. However, the discovery of broadly neutralizing antibodies (bnAbs) against divergent viruses has sparked renewed interest in a universal influenza vaccine and novel therapeutic opportunities. Here, a crystal structure at 1.70 Å resolution is presented of the Fab of the human antibody CH65, which has broad neutralizing activity against a range of seasonal H1 isolates. Previous studies proposed that affinity maturation of this antibody lineage pre-organizes the complementarity-determining region (CDR) loops into an energetically favorable HA-bound conformation. Indeed, from the structural comparisons of free and HA-bound CH65 presented here, the CDR loops, and in particular the heavy-chain CDR3, adopt the same conformations in the free and bound forms. Thus, these findings support the notion that affinity maturation of the CH65 lineage favorably preconfigures the CDR loops for high-affinity binding to influenza hemagglutinin.