Aims

Viral pathogens are the primary agents in bovine respiratory disease cases, and there is no directly effective antiviral drug application. Thymbra is a genus of oregano commonly found in Turkey. The primary component (34.9%) of the extract obtained from Thymbra spicata L. is the carvacrol using traditional medicine. This study evaluates the potential antiviral activity and inactivation efficiency of T. spicata L. extract against bovine respiratory viruses, including BCoV, BPIV-3, BRSV, BVDV, and BoHV-1.

Methods and Results

To evaluate its effect on virus replication, viral titers were taken from infected cells treated with non-cytotoxic T. spicata L. extract concentrations (0.75 and 1.5%, 1.32 and 2.64 µg/mL of carvacrol as active ingredient respectively) and compared to non-treated infected cells. The viruses were treated directly with 1.5% T. spicata L. extract, and the virus titers were evaluated at certain time points to determine the efficiency of direct inactivation. T. spicata L. extract strongly inhibits the replication of mentioned viruses in a dose-dependent manner in vitro. In addition, T. spicata L. extract shared direct inactivation efficiency on the mentioned viruses in a time-dependent manner.

Conclusion

This study shows the antiviral efficiency of T. spicata L. on BRD-related viral agents for the first time. The oregano species T. spicata and its main component, carvacrol, may have a potential for antiviral in the alternative treatment of respiratory viral diseases in cattle.

Significance and Impact of the Study

Given the similarity of replication strategies, obtained data suggest the possible efficiency of T. spicata L. on human respiratory viruses.