Investigation of monotherapy and combined anticoronaviral therapies against feline coronavirus serotype II in vitro

Abstract

Objectives Feline infectious peritonitis (FIP), caused by genetic mutants of feline enteric coronavirus known as FIPV, is a highly fatal disease of cats with no currently available vaccine or US Food and Drug Administration-approved cure. Dissemination of FIPV in affected cats results in a range of clinical signs, including cavitary effusions, anorexia, fever and lesions of pyogranulomatous vasculitis and perivasculitis, with or without central nervous system or ocular involvement. The objectives of this study were to screen an array of antiviral compounds for anti-FIPV (serotype II) activity, determine cytotoxicity safety profiles of identified compounds with anti-FIPV activity and strategically combine identified monotherapies to assess compound synergy against FIPV in vitro. Based upon clinically successful combination treatment strategies for human patients with HIV and hepatitis C virus infections, we hypothesized that a combined anticoronaviral therapy approach featuring concurrent multiple mechanisms of drug action would result in an additive or synergistic antiviral effect. Methods This study screened 90 putative antiviral compounds for efficacy and cytotoxicity using a multimodal in vitro strategy, including plaque bioassays, real-time RT-PCR viral inhibition and cytotoxicity assays. Results Through this process, we identified 26 compounds with effective antiviral activity against FIPV, representing a variety of drug classes and mechanisms of antiviral action. The most effective compounds include GC376, GS-441524, EIDD2081 and EIDD2931. We documented antiviral efficacy for combinations of antiviral agents, with a few examined drug combinations demonstrating evidence of limited synergistic antiviral activity. Conclusions and relevance Although evidence of compound synergy was identified for several combinations of antiviral agents, monotherapies were ultimately determined to be the most effective in the inhibition of viral transcription.

Serotype I and II Feline Coronavirus Replication and Gene Expression Patterns of Feline Cells—Building a Better Understanding of Serotype I FIPV Biology

“…FIPV II (WSU-79-1146; GenBank DQ010921) was propagated and viral infectivity was quantified in CRFK cells using a biological plaquing assay (median tissue culture infectious dose, TCID50); viral RNA was quantified using reverse transcription real-time polymerase chain reaction (RT-qPCR) as previously described [ 35 ]. FIPV I (Black I) and FCWF-4 CU cells were kindly donated by Dr. Susan Baker (Loyola University Chicago), originally obtained from Cornell University College of Veterinary Medicine (Dr. Edward Dubovi).…”

“…To determine the relative replication efficiencies of Black I and WSU 79-1146 (FIPV II) in the various cell types (CRFK, FCWF-4 ATCC, FCWF-4 CU, and feline monocyte-derived macrophages (feMDMs)), TCID50 was determined by a biological plaquing assay as previously described and published [ 35 ]. Goat synovial membrane (GSM) cells were utilized as a non-permissive negative control cell line.…”

Optionen zur Therapie der felinen infektiösen Peritonitis – früher und heute

“…Molnupiravir (EIDD-2801), ein Prodrug des Nukleosid-Analogons B-D-N4-Hydroxycytidin 59 , ist in vitro gegen FCoV wirksam 60 61 . Bei 26 Katzen mit FIP-Verdacht wurde in einer retrospektiven Studie Molnupiravir (durchschnittlich 12,8–14,7 mg/kg, q12h, PO) über einen Zeitraum von 84 Tagen angewendet; 10/26 Katzen hatten vorher bereits einen Therapiezyklus mit GS-441524 erhalten.…”

Serologic, Virologic and Pathologic Features of Cats with Naturally Occurring Feline Infectious Peritonitis Enrolled in Antiviral Clinical Trials

“…The closely related nucleoside analogs GS-441524 and remdesivir (Gilead Sciences, Foster City, CA, USA) have demonstrated clinical efficacy in treating cats with FIP [ 18 , 19 , 20 ]. The nucleoside analog molnupiravir (EIDD-2801, Merck, New York, NY, USA) has been shown to effectively inhibit FIPV replication in in vitro assays [ 21 , 22 ] and has demonstrated clinical efficacy in cats with naturally occurring FIP [ 23 ]. Mesenchymal stem/stromal cells (MSCs) are promising candidate therapeutics for viral infections given their potent anti-inflammatory and immunomodulatory properties.…”