Effects of crude extracts of various plants on infectious bovine rhinotracheitis virus-plaque production.

This research explored the antiviral activity of extracts from 28 different plants, specifically their capability to inhibit the plaque production of the infectious bovine rhinotracheitis virus. It was found that the ethanolic extract of Narcissus tazetta L bulb, in particular, displayed significant antiviral activity without having a negative impact on the virus itself or the cells it infects.

Investigated Plant Extracts and their Effect

• The primary goal of this study was to explore the potential antiviral properties of different plant extracts against the infectious bovine rhinotracheitis virus.
• The authors tested extracts from 28 plants through an agar-overlay plaque-reduction antiviral assay system.
• However, no noticeable antiviral activity was found in most of these plant extracts.

Narcissus tazetta L Bulb and Its Antiviral Activity

• On the contrary, the ethanolic extract of Narcissus tazetta L bulb demonstrated significant antiviral activity.
• This extract was found to inhibit the formation of viral plaques, signifying a substantial reduction in viral replication.
• Notably, the antiviral activity was also demonstrated against equine rhinopneumonitis viruses, showcasing the extract’s potential to be effective against multiple viral species.

Extracellular Inactivation, Cell Toxicity, and Drug Resistance

• An important finding was that the Narcissus extract did not directly inactivate the virus extracellularly, meaning that the virus remains viable outside the host cell.
• The extract showed only limited toxicity to rapidly multiplying bovine endocardial cells at plaque-inhibitory levels. This indicates that the extract could be safely used without causing significant harm to these cells.
• Furthermore, it was not cytotoxic to preformed confluent cell monolayers. This suggests that the extract does not have significant negative impacts on established cell populations.
• Interestingly, the Narcissus extract did not induce the formation of drug-resistant viral strains, which is an important quality for any potential antiviral treatment.