Essential oils expose diverse targets on non-enveloped ScV-L-A totivirus

The spread of novel viruses substantiates the need for alternative antiviral agents. Plant-based extracts, such as essential oils (EOs), are highly relevant due to their generally human-friendly nature and broad spectrum of bioactive properties. Most EO antiviral activity is targeting enveloped viruses. <i>Orthototiviridae</i> family yeast virus ScV-L-A offers a novel, safe, non-enveloped virus model system for antiviral substance evaluation. This study aimed to investigate the antiviral efficacy of EOs and their constituents against non-enveloped ScV-L-A totivirus. The composition of EOs was determined using GC-MS. Native ScV-L-A viral particles were prepared from yeast cells <i>via</i> cesium chloride gradient ultracentrifugation. The antiviral effect of EOs and their principal components was evaluated by following the synthesis of radio-labeled viral transcripts. TEM was employed to investigate the impact of target substances on ScV-L-A capsid integrity. Tested EOs inhibited viral RNA polymerase activity in both liquid and vapor phases. Citral-rich EOs exhibited the strongest antiviral action, with lemon myrtle EO possessing the lowest half-maximal inhibitory concentration and highest timewise efficacy. Coriander and mandarin EOs showed the lowest polymerase-inhibiting capacity. EOs were more efficient compared to the action of single compounds. All EOs except for that of mandarin, dominated by limonene, were more effective in the liquid rather than the vapor phase. Tea tree and mandarin EOs were found to damage ScV-L-A capsid structure. This study highlighted the efficacy of EOs in targeting non-enveloped viruses and revealed their potential for sustainable control of viral infection.