Paper

6',6'-Difluoro-aristeromycin is a potent inhibitor of MERS-coronavirus replication

Posthuma, Clara C, Zevenhoven-Dobbe, Jessika, Ogando, Natacha S S, Lak Shin Jeong, Tripathi, Sushil Kumar, Hyuk Woo Lee, Snijder, Eric J, Jarhad, Dnyandev

2021

Overview

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has highlighted the lack of treatments to combat infections with human or (potentially) zoonotic CoVs. Thus, it is critical to develop and evaluate antiviral compounds that either directly target CoV functions or modulate host functions involved in viral replication. Here, we demonstrate that low-micromolar concentrations of 6,6-difluoro-aristeromycin (DFA), an adenosine nucleoside analogue, strongly inhibit the replication of Middle East respiratory syndrome coronavirus (MERS-CoV) in a cell-based infection assay. DFA was designed to target S-adenosylhomocysteine (SAH) hydrolase and, consequently, may affect intracellular levels of the methyl donor S-adenosylmethionine, which is used by two CoV methyltransferases involved in the capping of the 5 end of the viral mRNAs. Passaging of wild-type MERS-CoV in the presence of DFA selected a virus population with a ~100-fold decreased DFA sensitivity, which carried various amino acid substitutions in viral nonstructural proteins (nsps). Specifically, mutations were present in the RNA polymerase subunit (nsp12) and in nsp13, the helicase subunit containing a nucleoside triphosphate hydrolase activity that has been implicated in CoV capping. We hypothesize that DFA directly or indirectly affects viral cap methylation, either by inhibiting the viral enzymes involved or by binding to SAH hydrolase. We also evaluated the antiviral activity of DFA against other betacoronaviruses, but found it to have limited impact on their replication, while being quite cytotoxic to the Calu-3 cells used for this comparison. Nevertheless, our results justify the further characterization of DFA derivatives as an inhibitor of MERS-CoV replication. Competing Interest Statement The authors have declared no competing interest. Footnotes * - sequencing data. - shortened the theoretical part. - updated Figure 3 and Table 1.

• Publisher: Cold Spring Harbor Laboratory Press,Cold Spring Harbor Laboratory
• Subject: Adenosine / Adenosylmethionine / Amino acids / Antiviral activity / Coronaviruses / Cytotoxicity / Drug resistance / Hydrolase / Intracellular levels / Methylation / Methyltransferase / Microbiology / Middle East respiratory syndrome / Nonstructural proteins / Nucleoside analogs / Pandemics / Replication / Respiratory diseases / S-Adenosylmethionine / Severe acute respiratory syndrome coronavirus 2