The Discovery of Antivirals and Targets for SARS‐CoV‐2 and EV‐A71

ABSTRACT

Positive Strand RNA (PSR) viruses, such as coronaviruses and enteroviruses, cause serious health and economic threats worldwide, as currently seen with the COVID‐19 pandemic. This has drawn attention to the importance of identifying new antivirals and molecular targets in RNA viruses. The multifunctionality of PSR genomes make them desirable targets for therapeutic intervention. Here, we present a class of antivirals that can inhibit SARS‐CoV‐2 replication invitro by targeting conserved viral RNA structures at the 5’‐end. Specifically, stem loops 1, 4, 5a, and 6 of the viral 5’‐region have shown a degree of binding with these small molecules as determined by NMR structural analysis. These results open the door to potentially develop specific small molecules against SARS‐CoV‐2 and related coronaviruses. Additionally, Enterovirus A71 (EV‐A71), which is the etiological agent of the hand, foot, and mouth disease, has caused severe morbidity and high mortality rates in children for decades. Thus, understanding the mechanisms by which EV‐A71 replicates within the cellular environment can bring to light efficient drug targets for viral inhibition. The multifunctional viral protein, 3C protease (3Cpro), is essential for viral protein and RNA synthesis. Here, we investigate how RNA binding allosterically modulates the enzymatic activity of 3Cpro. We identify an overlooked dimerization surface on 3Cpro that is proximal to its active site and distal to its RNA binding domain. Our data show that RNA binding is allosterically coupled to 3Cpro dimerization, and we posit that this is a novel mechanism to regulate its enzymatic function. To that point, single, double, and triple point mutations in the 3Cpro dimerization domain attenuates viral growth and kinetics. Taken together, we present compelling data that demonstrates novel targeting surfaces on 3Cpro that can be pursued as antiviral targets.