Non-Nucleoside Inhibitors Decrease Foot-and-Mouth Disease Virus Replication by Blocking the Viral 3Dpol

Abstract

Foot-and-mouth disease virus (FMDV), an economically important pathogen of cloven-hoofed livestock, is a positive-sense, single-stranded RNA virus classified in the Picornaviridae family. RNA-dependent RNA polymerase (RdRp) of RNA viruses is highly conserved. Compounds that bind to the RdRp active site can block viral replication. Herein, we combined double virtual screenings and cell-based antiviral approaches to screen and identify potential inhibitors targeting FMDV RdRp (3Dpol). From 5596 compounds, the blind- followed by focus-docking filtered 21 candidates fitting in the 3Dpol active sites. Using the BHK-21 cell-based assay, we found that four compounds—NSC217697 (quinoline), NSC670283 (spiro compound), NSC292567 (nigericin), and NSC65850— demonstrated dose-dependent antiviral actions in vitro with the EC50 ranging from 0.78 to 3.49 µM. These compounds could significantly block FMDV 3Dpol activity in the cell-based 3Dpol inhibition assay with small IC50 values ranging from 0.8 nM to 0.22 µM without an effect on FMDV’s main protease, 3Cpro. The 3Dpol inhibition activities of the compounds were consistent with the decreased viral load and negative-stranded RNA production in a dose-dependent manner. Conclusively, we have identified potential FMDV 3Dpol inhibitors that bound within the enzyme active sites and blocked viral replication. These compounds might be beneficial for FMDV or other picornavirus treatment.

First study on in vitro antiviral and virucidal effects of flavonoids against feline infectious peritonitis virus at the early stage of infection

“…Our results revealed its antiviral effect against FIPV replication. Similar results have been shown for influenza A virus [26], respiratory syncytial virus [27], and FMDV [35]. Luteolin had an inhibitory activity against SARS-CoV-2 RdRp with an IC 50 value of 4.6 µM [28].…”

“…In addition, isoginkgetin could inhibit FMDV 3C pro activity with a half-maximal inhibitory concentration (IC 50 ) value of 39.03 µM [35]. Footand-mouth disease virus 3C pro is a chymotrypsin-like cysteine protease, which processes viral polyproteins for the virus life cycle as well as interact with 3CL pro of CoVs [35]. These studies confirm that isoginkgetin inhibits viral proteases of CoVs and picornaviruses.…”

“…Thus, the inhibition mechanisms of this compound on FIPV 3CL pro activity must be evaluated. In addition to its antiprotease effects, isoginkgetin acts as a virucidal when the virus and compounds are cotreated before incubating with cells (EC 50 = 2.01 ± 0.07 µM) [35], which corresponds to the virucidal effect on FIPV in our study. Isoginkgetin exerts antiviral activity by inactivating the virus at a high concentration, possibly by interfering with lipid envelope stability [35,38].…”

“…In addition to its antiprotease effects, isoginkgetin acts as a virucidal when the virus and compounds are cotreated before incubating with cells (EC 50 = 2.01 ± 0.07 µM) [35], which corresponds to the virucidal effect on FIPV in our study. Isoginkgetin exerts antiviral activity by inactivating the virus at a high concentration, possibly by interfering with lipid envelope stability [35,38]. In the virucidal assay, isoginkgetin was stable and effective on FIPV upon inactivation for 120 min; therefore, it could reduce secreted viral particles on the material surface.…”

“…Isoginkgetin could inhibit foot-and-mouth disease virus (FMDV) during post-viral entry, with an EC 50 value of 1.93 ± 0.21 µM. In addition, isoginkgetin could inhibit FMDV 3C pro activity with a half-maximal inhibitory concentration (IC 50 ) value of 39.03 µM [35]. Footand-mouth disease virus 3C pro is a chymotrypsin-like cysteine protease, which processes viral polyproteins for the virus life cycle as well as interact with 3CL pro of CoVs [35].…”