Application of a Dynamic Map for Learning, Communicating, Navigating, and Improving Therapeutic Development.

Drug discovery and development is commonly schematized as a "pipeline," and, although appreciated by drug developers to be a useful oversimplification, this cartology may perpetuate inaccurate notions of straightforwardness and is of minimal utility for process engineering to improve efficiency. To create a more granular schema, a group of drug developers, researchers, patient advocates, and regulators developed a crowdsourced atlas of the steps involved in translating basic discoveries into health interventions, annotated with the steps that are particularly prone to difficulty or failure. This Drug Discovery, Development, and Deployment Map (4DM), provides a network view of the process, which will be useful for communication and education to those new to the field, orientation and navigation of individual projects, and prioritization of technology development and re-engineering endeavors to improve efficiency and effectiveness. The 4DM is freely available for utilization, modification, and further development by stakeholders across the translational ecosystem.

Intermonomer Interactions in Hemagglutinin Subunits HA1 and HA2 Affecting Hemagglutinin Stability and Influenza Virus Infectivity.

UNLABELLED: Influenza virus hemagglutinin (HA) mediates virus entry by binding to cell surface receptors and fusing the viral and endosomal membranes following uptake by endocytosis. The acidic environment of endosomes triggers a large-scale conformational change in the transmembrane subunit of HA (HA2) involving a loop (B loop)-to-helix transition, which releases the fusion peptide at the HA2 N terminus from an interior pocket within the HA trimer. Subsequent insertion of the fusion peptide into the endosomal membrane initiates fusion. The acid stability of HA is influenced by residues in the fusion peptide, fusion peptide pocket, coiled-coil regions of HA2, and interactions between the surface (HA1) and HA2 subunits, but details are not fully understood and vary among strains. Current evidence suggests that the HA from the circulating pandemic 2009 H1N1 influenza A virus [A(H1N1)pdm09] is less stable than the HAs from other seasonal influenza virus strains. Here we show that residue 205 in HA1 and residue 399 in the B loop of HA2 (residue 72, HA2 numbering) in different monomers of the trimeric A(H1N1)pdm09 HA are involved in functionally important intermolecular interactions and that a conserved histidine in this pair helps regulate HA stability. An arginine-lysine pair at this location destabilizes HA at acidic pH and mediates fusion at a higher pH, while a glutamate-lysine pair enhances HA stability and requires a lower pH to induce fusion. Our findings identify key residues in HA1 and HA2 that interact to help regulate H1N1 HA stability and virus infectivity. IMPORTANCE: Influenza virus hemagglutinin (HA) is the principal antigen in inactivated influenza vaccines and the target of protective antibodies. However, the influenza A virus HA is highly variable, necessitating frequent vaccine changes to match circulating strains. Sequence changes in HA affect not only antigenicity but also HA stability, which has important implications for vaccine production, as well as viral adaptation to hosts. HA from the pandemic 2009 H1N1 influenza A virus is less stable than other recent seasonal influenza virus HAs, but the molecular interactions that contribute to HA stability are not fully understood. Here we identify molecular interactions between specific residues in the surface and transmembrane subunits of HA that help regulate the HA conformational changes needed for HA stability and virus entry. These findings contribute to our understanding of the molecular mechanisms controlling HA function and antigen stability.