Anti-SARS-CoV-2 Agents in Artemisia Endophytic Fungi and Their Abundance in Artemisia vulgaris Tissue

Coronavirus disease 2019 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Therapeutic agents for the disease are being developed. Endophytes are diverse and produce various secondary metabolites and bioactive substances. We isolated 13 endophytes from the leaves and stems of Artemisia vulgaris. Antiviral testing using the culture extracts of these endophytic fungi revealed that five isolates effectively inhibited the replication of SARS-CoV-2. These extracts were used to study the inhibitory effect of SARS-CoV-2 on 3C-like protease, and two isolates proved useful. Both isolates were from the genus Colletotrichum; therefore, the percentage of Artemisia endophytic fungi in the plant tissue was observed to be an important factor in plant site selection. Thus, we conducted a macroanalysis using next-generation sequencing to analyze the percentage of endophytes in the stems (whole, skin, and inner), leaves, roots, and cultivating soil, as well as to determine the location of each genus. To the best of our knowledge, this study is the first to report that Colletotrichum spp. are abundant in stems and that stem-based methods are the most efficient for isolating endophytes targeting Colletotrichum spp.