Structure-guided design of protease-resistant, lipopeptide inhibitors of SARS-CoV-2

PROJECT SUMMARY Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), the etiological agent of coronavirus disease (COVID-19), has spurred an unprecedented global pandemic. Infection surges necessitate new therapeutic agents that are effective against a rapidly changing virus. Antivirals that inhibit viral entry into host cells have proven effective against other viruses with similar mechanisms of pathogenesis. The long-term objective of this highly collaborative proposed research is to develop potent peptides inhibitors of SARS-CoV-2 infection that operate by blocking structural rearrangements of the spike protein required for viral entry into host cells. For SARS-CoV-2 infection to occur, the viral surface spike (S) protein, a homotrimer, rearranges to form an energetically favored postfusion state. In this postfusion conformation, two helical domains, the N-terminal (HRN) and C-terminal (HRC) heptad repeats, associate to form a 6-helix bundle (6HB). Peptides derived from the HRC can inhibit formation of the 6HB, and thus SARS-CoV-2 infection. However, conventional peptides, composed entirely of α-amino acid residues, are highly susceptible to proteolytic degradation, which necessitates frequent and high dosing. The Gellman lab, in collaboration with virologists Prof. Anne Moscona and Prof. Matteo Porotto at Columbia University, has demonstrated that site- selective incorporation of backbone modifications, in combination with cholesterol conjugation, can decrease proteolytic sensitivity while maintaining high antiviral potency. Our team recently found that such lipopeptides can inhibit SARS-CoV-2 infection in biological assays and animal models, and that these inhibitors are effective against SARS-CoV-2 variants, SARS-CoV-1 and MERS. Building on this foundation, my proposed project seeks to develop lipopeptides containing backbone modifications that display high antiviral potency and resist proteolysis. Aim 1 will produce potent inhibitors of SARS-CoV-2 (and other coronaviruses) that contain backbone modifications and resist proteolysis. Aim 2 will evaluate the stability of 6HB formation between inhibitor candidates and the native SARS-CoV-2 HRN. Aim 3 will elucidate critical structural interactions between the HRC mimics and the native HRN. My hypothesis is that site-selective incorporation of backbone modifications into HRC-based designs will increase both antiviral activity and half-life in vivo, improving therapeutic efficacy. The proposed research, which will be conducted under the guidance of Prof. Sam Gellman at the University of Wisconsin, will provide me with experience in macromolecular X-ray crystallography, molecular design, protein engineering & expression, and virology. Through structure-guided engineering and sophisticated and multi-pronged assay implementation, these efforts could generate effective pan-variant therapeutics for COVID-19.