Homoseongomycin, a compound isolated from marine actinomycete bacteria K3-1, is a potent inhibitor of encephalitic alphaviruses.

Abstract

Marine microorganisms have been a resource for novel therapeutic drugs for decades. In addition to anticancer drugs, the drug acyclovir, derived from a marine sponge, is FDA-approved for the treatment of human herpes simplex virus-1 infections. Most alphaviruses that are infectious to terrestrial animals and humans, such as Venezuelan and eastern equine encephalitis viruses (VEEV and EEEV), lack efficient antiviral drugs and it is imperative to develop these remedies. To push the discovery and development of anti-alphavirus compounds forward, this study aimed to isolate and screen for potential antiviral compounds from cultured marine microbes originating from the marine environment. Compounds from marine microbes were of interest as they are prolific producers of bioactive compounds across the spectrum of human diseases and infections. Homoseongomycin, an actinobacteria isolated from a marine sponge displayed impressive activity against VEEV from a total of 76 marine bioactive products. The 50% effective concentration (EC50) for homoseongomycin was 8.6 μM for suppressing VEEV TC-83 luciferase reporter virus replication. Homoseongomycin was non-toxic up to 50 μM and partially rescued cells from VEEV induced cell death. Homoseongomycin exhibited highly efficient antiviral activity with a reduction of VEEV infectious titers by 8 log10 at 50 μM. It also inhibited EEEV replication with an EC50 of 1.2 μM. Mechanism of action studies suggest that homoseongomycin affects both early and late stages of the viral life cycle. Cells treated with 25 μM of homoseongomycin had a ~90% reduction in viral entry. In comparison, later stages showed a more robust reduction in infectious titers (6 log10) and VEEV extracellular viral RNA levels (4 log10), but a lesser impact on intracellular viral RNA levels (1.5 log10). In sum, this work demonstrates that homoseongomycin is a potential anti-VEEV and anti-EEEV compound due to its low cytotoxicity and potent antiviral activity.

• Authors: Shih-Chao Lin, Caitlin W Lehman, Allison K Stewart, Lauren Panny, Nicole Bracci, Jeffrey L C Wright, Mikell Paige, Wendy K Strangman, Kylene Kehn-Hall
• Journal: Antiviral research (Antiviral Res) Vol. 191 Pg. 105087 (07 2021) ISSN: 1872-9096 [Electronic] Netherlands
• PMID: 33965437 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2021 Elsevier B.V. All rights reserved.

Chemical References

• Antiviral Agents
• Fluorenes
• homoseongomycin

Topics

• Actinobacteria (chemistry)
• Animals
• Antiviral Agents (pharmacology)
• Aquatic Organisms (chemistry)
• Cell Line
• Chlorocebus aethiops
• Encephalitis Virus, Eastern Equine (drug effects)
• Encephalitis Virus, Venezuelan Equine (drug effects)
• Fluorenes (pharmacology)
• Humans
• Vero Cells
• Virus Replication (drug effects)