Current advances in the diagnosis and treatment of feline calicivirus

This review summarizes and analyzes the results of scientific research on the diagnosis and treatment of feline calicivirus (FCV) infection. It has been established that continuous monitoring of the phylogenetic and molecular-genetic characteristics of FCV is essential for developing new effective primer sets for its PCR-based diagnosis. The oral cavity is identified as the preferred site for sample collection for FCV detection. Various advanced diagnostic methods have been developed, including a reverse transcription PCR (RT-PCR) method with CRISPRCas13a trans-cleavage activity, the ERA method combined with LFD (Lateral Flow Device) targeting the FCV-ORF1 region, and fluorescent isothermal analysis using Recombinase Polymerase Amplification (RPA) for rapid FCV detection. Additionally, an ultrasensitive visual detection method for FCV and FHV-1 using a single-tube dRPA-Cas12a/Cas13a assay, a triple nanoPCR method for FCV, FPV, and FHV-1 detection, and a TaqMan MGB fluorescent quantitative PCR method for simultaneous detection of FPV, FHV-1, FCV, and FIPV have been developed. Furthermore, a single PCR assay has enabled the simultaneous detection and genetic differentiation of vaccine and field strains of the virus. Effective systemic antiviral therapy for FCV is currently not developed. Consequently, supportive and symptomatic therapy, along with high-quality nursing care and feeding, play a key role in the management of infected cats. Clinical studies have shown that nitazoxanide, mizoribine, and CpG49 possess antiviral activity, while PSSNa has demonstrated good efficacy for topical application. Administration of antibodies against FHV-1 and FCV leads to a relatively rapid reduction in the severity of respiratory symptoms and overall improvement in well-being. There is evidence of a positive effect of "Roncoleukin" and "Gamapren" on FCVinfected cats and their clinical and laboratory parameters, while the administration of feline interferon combined with "Remaxol" positively influences the pro- and antioxidant balance. In vitro studies have revealed a strong inhibitory effect against FCV by mefloquine, AZD6244, sclareol, NTZ, 2CMC, NITD-008, copper chloride, and lithium chloride. Antiviral activity has also been observed for certain plant extracts, ICA, FMN, and CPAE. Survivin overexpression leads to reduced FCV infection. The secretome of feline mesenchymal stem cells does not prevent FCV entry into CRFK cells but exerts an antiviral effect on viral replication. There is also evidence regarding the potential therapeutic application of RNA interference in FCV.

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