A Single Peptide That Blocks All Human Coronaviruses — Developed Before COVID-19

The researchers designed peptides based on the HR2 domains of various human coronaviruses, then tested them for fusion inhibition against a panel of HCoVs in cell culture. The lead peptide EK1 was optimized for potency. In vivo efficacy was tested in mice infected with HCoV-OC43. Crystal structures of EK1 bound to HR1 domains from different coronaviruses were solved to understand the structural basis of broad-spectrum activity.

This study was published in April 2019 — months before SARS-CoV-2 emerged. It demonstrated that a single peptide could block all known human coronaviruses, essentially predicting the need for pan-coronavirus therapeutics. The EK1 peptide and its derivatives became immediately relevant when COVID-19 struck, and this work laid the groundwork for pandemic-preparedness research using peptide fusion inhibitors.

This study is a landmark in pandemic preparedness. Published just months before SARS-CoV-2 appeared, it proved that broad-spectrum peptide antivirals against coronaviruses were possible. When COVID-19 hit, EK1 was quickly tested and shown to work against SARS-CoV-2. The approach — targeting a conserved fusion mechanism rather than a variable surface feature — is a strategy that could provide protection against future coronavirus variants and even entirely new coronaviruses.

Only tested in mice (HCoV-OC43 model), not in humans or non-human primates. The study predates SARS-CoV-2, so efficacy against COVID-19 was not tested (though it was later shown to work against SARS-CoV-2). Peptide drugs face pharmacokinetic challenges including short half-life and poor oral bioavailability. Manufacturing scale-up for pandemic use was not addressed.