title: In vitro inhibition of field isolates of feline calicivirus with short interfering RNAs (siRNAs).
abstract: Feline calicivirus (FCV) is a common infection of domestic cats. Most infections are mild and self-limiting; however more severe disease manifestations, such as FCV-associated virulent systemic disease, may be associated with significant morbidity and mortality. There is currently a lack of effective antiviral treatments for these disease manifestations. In this study, a panel of eight siRNAs were designed to target four conserved regions of the FCV genome. siRNAs were screened for in vitro antiviral efficacy against the reference strain FCV F9 by determination of extracellular virus titres and morphological assessment of protection from cytopathic effect. Three of the siRNA (FCV3.7, FCV4.1, and FCV4.2) demonstrated a marked antiviral effect with a greater than 99% reduction in extracellular viral titre. Titration of these effective siRNAs demonstrated a clear concentration-response relationship, with IC50 values of approximately 1 nM, and combination treatment with multiple siRNAs demonstrated additive or synergistic effects. To assess the potential usefulness of the compounds in a clinical setting, siRNAs were screened against a panel of six recent Australian FCV isolates from cats with FCV-related disease. The siRNAs shown to be effective against the reference strain FCV F9 were active against the majority of the isolates tested, although some variability was noted. Taken together these data suggest potential therapeutic application of antiviral RNAi for treating FCV-associated disease in cats.
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Building B14, Sydney, NSW 2006, Australia. Electronic address: phillip.mcdonagh@sydney.edu.au.
authors.forename: Phillip
authors.initials: P
authors.lastname: McDonagh
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Building B19, Sydney, NSW 2006, Australia. Electronic address: paul.sheehy@sydney.edu.au.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Sheehy
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Building B03, Sydney, NSW 2006, Australia. Electronic address: anne.fawcett@sydney.edu.au.
authors.forename: Anne
authors.initials: A
authors.lastname: Fawcett
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Building B14, Sydney, NSW 2006, Australia. Electronic address: jacqui.norris@sydney.edu.au.
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Norris
mesh_terms: D000818:Animals; D001315:Australia; D017250:Caliciviridae Infections / Q000662:veterinary*; D017927:Calicivirus, Feline; D002371:Cat Diseases / Q000821:virology*; D002415:Cats; D002460:Cell Line; D015967:Gene Expression Regulation, Viral / Q000502:physiology; D007668:Kidney / Q000166:cytology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D019562:Viral Load
chemical_list: D034741:RNA, Small Interfering
keywords: Antiviral; Cats; Feline calicivirus; RNA interference; Short interfering RNA