Open Access
Research (Published online: 26-03-2023)
24. First study on in vitro antiviral and virucidal effects of flavonoids against feline infectious peritonitis virus at the early stage of infection
Chanittha Triratapiban, Varanya Lueangaramkul, Nantawan Phecharat, Achiraya Pantanam, Porntippa Lekcharoensuk, and Sirin Theerawatanasirikul
Veterinary World, 16(3): 618-630

Chanittha Triratapiban: Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok 10900, Thailand.
Varanya Lueangaramkul: Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok 10900, Thailand.
Nantawan Phecharat: Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok 10900, Thailand.
Achiraya Pantanam: Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok 10900, Thailand.
Porntippa Lekcharoensuk: Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok 10900, Thailand; Center for Advanced Studies in Agriculture and Food, Kasetsart University Institute for Advanced Studies, Kasetsart University, Bangkok 10900, Thailand.
Sirin Theerawatanasirikul: Department of Anatomy, Faculty of Veterinary Medicine, Kasetsart University, Bangkok 10900, Thailand.

doi: 10.14202/vetworld.2023.618-630

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Article history: Received: 09-11-2022, Accepted: 13-02-2023, Published online: 26-03-2023

Corresponding author: Sirin Theerawatanasirikul

E-mail: fvetsrth@ku.ac.th

Citation: Triratapiban C, Lueangaramkul V, Phecharat N, Pantanam A, Lekcharoensuk P, and Theerawatanasirikul S (2023) First study on in vitro antiviral and virucidal effects of flavonoids against feline infectious peritonitis virus at the early stage of infection, Veterinary World, 16(3): 618-630.
Abstract

Background and Aim: Feline infectious peritonitis (FIP), one of the most important infectious diseases in cats is caused by FIP virus (FIPV), a mutated variant of feline coronavirus. Feline infectious peritonitis has a negative impact on feline health, with extremely high mortality in clinical FIP-infected cats, particularly young cats. There are no approved drugs for FIP treatment, and therapeutic possibilities for FIP treatment are limited. This study aimed to utilize nature-derived bioactive flavonoids with antiviral properties to inhibit FIPV infection in Crandell–Rees feline kidney (CRFK) cells.

Materials and Methods: The cytotoxicity of 16 flavonoids was evaluated on CRFK cells using a colorimetric method (MTS) assay. Viral kinetics of FIPV at 50 tissue culture infectious dose (TCID50)/well was determined during the first 24-h post-infection (HPI). Antiviral activity was evaluated based on the replication steps of the virus life cycle, including pre-compound, attachment, penetration, post-viral entry, and virucidal assays. The antiviral efficacy of flavonoids against FIPV was determined based on positive FIPV-infected cells with the immunoperoxidase monolayer assay and viral load quantification using reverse transcription-quantitative polymerase chain reaction.

Results: Two flavonoids, namely, isoginkgetin and luteolin, inhibited FIPV replication during post-viral entry in a dose-dependent manner, with 50% maximal effective concentrations = 4.77 ± 0.09 and 36.28 ± 0.03 μM, respectively. Based on viral kinetics, both flavonoids could inhibit FIPV replication at the early stage of infection at 0–6-HPI for isoginkgetin and 2–6-HPI for luteolin using a time-of-addition assay. Isoginkgetin exerted a direct virucidal effect that reduced the viral titers by 2 and 1.89 log10 TCID50/mL at 60 and 120 min, respectively.

Conclusion: Isoginkgetin interfered with FIPV replication during both post-viral infection and virucidal experiments on CRFK cells, whereas luteolin inhibited the virus after infection. These results demonstrate the potential of herbal medicine for treating FIP.

Keywords: antiviral, feline coronavirus, feline infectious peritonitis virus, flavonoids, infectious disease.