In vitro antiviral activity and kinetics of the inhibitory effect of some compounds against Feline calicivirus strain F9 – a surrogate model of human noroviruses

In recent decades, searching for compounds inhibiting the caliciviruses (in particular the noroviruses) is of major scientific interest due to their substantial role in the infectious pathology. The development of effective anticalicivirus chemotherapy is important due to the lack of specific means for treatment and prevention of the calicivirus infections. Based on the previously obtained results from a screening for antiviral activity against Feline calicivirus (FCV) strain F9, four efficient antiviral compounds - oxoglaucine, ribavirin, PTU-23 and HBB were selected for further investigations. Cytotoxicity values and antiviral activity of the compounds were determined by neutral red uptake assay vs. three virus inoculation doses – 10, 100 and 1000 CCID50 of FCV-F9 in Crandell-Reese feline kidney cell line (CRFK). A significant activity against FCV-F9 of oxoglaucine was detected; the compound ribavirin exhibited a moderate activity, while the compounds PTU-23 and HBB showed insignificant anticalicivirus effect. Kinetics of the antiviral activity of the tested compounds against FCV-F9 was determined by the one-step virus growth cycle experimental design in CRFK cells. All tested compounds showed activity against FCV-F9 when applied in the first hours after the virus infection (during the early stages of virus replication cycle).