2022 AAFP/EveryCat Feline Infectious Peritonitis Diagnosis Guidelines.

CLINICAL IMPORTANCE: Feline infectious peritonitis (FIP) is one of the most important infectious diseases and causes of death in cats; young cats less than 2 years of age are especially vulnerable. FIP is caused by a feline coronavirus (FCoV). It has been estimated that around 0.3% to 1.4% of feline deaths at veterinary institutions are caused by FIP. SCOPE: This document has been developed by a Task Force of experts in feline clinical medicine as the 2022 AAFP/EveryCat Feline Infectious Peritonitis Diagnosis Guidelines to provide veterinarians with essential information to aid their ability to recognize cats presenting with FIP. TESTING AND INTERPRETATION: Nearly every small animal veterinary practitioner will see cases. FIP can be challenging to diagnose owing to the lack of pathognomonic clinical signs or laboratory changes, especially when no effusion is present. A good understanding of each diagnostic test's sensitivity, specificity, predictive value, likelihood ratio and diagnostic accuracy is important when building a case for FIP. Before proceeding with any diagnostic test or commercial laboratory profile, the clinician should be able to answer the questions of 'why this test?' and 'what do the results mean?' Ultimately, the approach to diagnosing FIP must be tailored to the specific presentation of the individual cat. RELEVANCE: Given that the disease is fatal when untreated, the ability to obtain a correct diagnosis is critical. The clinician must consider the individual patient's history, signalment and comprehensive physical examination findings when selecting diagnostic tests and sample types in order to build the index of suspicion 'brick by brick'. Research has demonstrated efficacy of new antivirals in FIP treatment, but these products are not legally available in many countries at this time. The Task Force encourages veterinarians to review the literature and stay informed on clinical trials and new drug approvals.

Correlation of Feline Coronavirus Shedding in Feces with Coronavirus Antibody Titer.

BACKGROUND: Feline coronavirus (FCoV) infection is ubiquitous in multi-cat households. Responsible for the continuous presence are cats that are chronically shedding a high load of FCoV. The aim of the study was to determine a possible correlation between FCoV antibody titer and frequency and load of fecal FCoV shedding in cats from catteries. METHODS: Four fecal samples from each of 82 cats originating from 19 German catteries were examined for FCoV viral loads by quantitative reverse transcriptase polymerase chain reaction (RT-qPCR). Additionally, antibody titers were determined by an immunofluorescence assay. RESULTS: Cats with antibodies were more likely to be FCoV shedders than non-shedders, and there was a weak positive correlation between antibody titer and mean fecal virus load (Spearman r = 0.2984; p = 0.0072). Antibody titers were significantly higher if cats shed FCoV more frequently throughout the study period (p = 0.0063). When analyzing only FCoV shedders, cats that were RT-qPCR-positive in all four samples had significantly higher antibody titers (p = 0.0014) and significantly higher mean fecal virus loads (p = 0.0475) than cats that were RT-qPCR-positive in only one, two, or three samples. CONCLUSIONS: The cats' antibody titers correlate with the likelihood and frequency of FCoV shedding and fecal virus load. Chronic shedders have higher antibody titers and shed more virus. This knowledge is important for the management of FCoV infections in multi-cat environments, but the results indicate that antibody measurement cannot replace fecal RT-qPCR.

Phylogenetic analysis of feline infectious peritonitis virus, feline enteric coronavirus, and severe acute respiratory syndrome coronavirus 2 of cats in Surabaya, Indonesia.

Background and Aim: Questions about the origin of coronavirus and its introduction to human beings have persisted. The detection of a variety of coronavirus related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in bats and pangolins led to the widespread belief that SARS-CoV-2 originated from wild ani-mals and was introduced to humans through an inter-mediate animal. Thus, coronaviruses from animals, especially those in close contact with humans, have attracted particular attention. This study aimed to phylogenetically analyze feline enteric coronavirus (FECV), feline infectious peritonitis virus (FIPV), and SARS-CoV-2 found in cats in Surabaya amid the COVID-19 pandemic. The results will provide a basis for developing basic preventive and pet healthcare strategies. Materials and Methods: Samples were collected on physical examinations of domestic and Persian cats (males and females) from March 2020 to March 2022. Samples were collected if there were clinical signs of FECV and FIP based on a veterinarian's diagnosis in several clinics in Surabaya. Laboratory examinations in this study were performed by reverse-transcription-polymerase chain reaction (RT-PCR) with primers for conserved regions of FIP and FECV, DNA sequencing was performed with Applied Biosystem Genetic Analyzer protocol, homology analysis was performed using Basic Local Alignment Search Tool NCBI, phylogenetic analysis was carried out with BioEdit 7.2 software, and sequences were compared with references from GenBank. Results: Samples were collected from ten cats showing clinical signs of FECV and FIP, based on a veterinarian's diagnosis. On RT-PCR examinations performed with specifically designed primers for detecting FIPV in blood, peritoneal fluid, and feces, only one sample showed positivity for FIPV (1/10), namely, a peritoneal sample from a domestic cat in Surabaya. Homology analysis of the FIPV Surabaya isolate showed 98% similarity with FECV and FIPV reported in GenBank (MT444152 and DQ010921, respectively). In phylogenetic analysis, the FIPV Surabaya isolate was clustered together with SARS-CoV-2 of Clade A (MT198653) from Spain, SARS-CoV-2 Clade A (MT192765) from the USA, SARS-CoV-2 Clade D (039888) from the USA, and SARS-CoV-2 Clade F (MT020781) from Finland. Conclusion: This study revealed a relationship between the SARS-CoV-2 viruses that infect humans and cats (FECV), which is an important finding for those keeping cats at home. However, this finding requires further comprehensive support from laboratory studies.

An updated review of feline coronavirus: mind the two biotypes.

Feline coronavirus (FCoV) includes two biotypes: feline infectious peritonitis virus (FIPV) and feline enteric coronavirus (FECV). Although both biotypes can infect cats, their pathogenicities differ. The FIPV biotype is more virulent than the FECV biotype and can cause peritonitis or even death in cats, while most FECV biotypes do not cause lesions. Even pathogenic strains of the FECV biotype can cause only mild enteritis because of their very low virulence. This article reviews recent progress in FCoV research with regard to FCoV etiological characteristics; epidemiology; clinical symptoms and pathological changes; pathogenesis; and current diagnosis, prevention and treatment methods. It is hoped that this review will provide a reference for further research on FCoV and other coronaviruses.

Feline Coronavirus RT-PCR Assays for Feline Infectious Peritonitis Diagnosis

Feline infectious peritonitis (FIP) is a highly fatal systemic disease in cats, caused by feline coronavirus (FCoV) infection. FCoV usually has little clinical significance;however, a mutation of this avirulent virus (feline enteric coronavirus) to a virulent type (FIP virus) can lead to FIP incidence. It is difficult to diagnose FIP, since the viruses cannot be distinguished using serological or virological methods. Recently, genetic techniques, such as RT-PCR, have been conducted for FIP diagnosis. In this chapter, the reliability of RT-PCR and procedures used to determine FCoV infection as part of antemortem FIP diagnosis is described. Copyright © Springer Science+Business Media New York 2016.

Fecal Feline Coronavirus Shedding and Spike Gene Mutations in Cats with Feline Infectious Peritonitis Treated with GS-441524

Feline infectious peritonitis (FIP) caused by feline coronavirus (FCoV) is a fatal disease if untreated. A recent prospective controlled treatment trial in field cats with confirmed FIP demonstrated excellent efficacy of GS-441524. The aims of this study were to investigate the effect of GS-441524 treatment on fecal FCoV RNA shedding and presence of FCoV spike (S-) gene mutations in different body compartments in treated FIP cats as well as in 12 companion cats cohabitating with the FIP cats. Eighteen cats with confirmed FIP were treated with oral GS-441524 for 84 days. Viral loads in feces, blood, and effusion were determined by RT-qPCR. In the first three days of treatment, 11/18 treated FIP cats (61%) shed FCoV RNA in feces, but all of them tested negative by day six. In one of them, fecal shedding reoccurred on day 83. Two cats initially negative in feces were transiently positive 1-4 weeks into the treatment. FCoV RNA loads in feces decreased in all treated FIP cats with time, comparable with those in blood and effusion. Sgene mutations linked to systemic FCoV spread were consistently found in blood and effusion from treated FIP cats, but not in feces from treated or companion cats. Phylogenetic analyses of the S-gene revealed a clustering of fecal samples of the companion cats with the corresponding FIP cats. Oral treatment with GS-441524 effectively decreased viral RNA loads in feces, blood, and effusion in cats with FIP. Nonetheless, reshedding can occur, most likely if cats are re-exposed to FCoV.

A case series of 25 cats with effusive and non-effusive feline infectious peritonitis treated with a combination of remdesivir and GS-441524

Feline infectious peritonitis (FIP) has until recently carried a guarded prognosis due to a lack of efficacious treatments. Preliminary studies using remdesivir and GS-441524 for treatment of FIP have shown promising results. Licensing of these drugs for use in humans with COVID-19 has resulted in improved accessibility for veterinary use in the UK. This case series describes clinical outcomes of cats with FIP treated with injectable remdesivir and oral GS-441524. Twenty-five cats were diagnosed with FIP at a referral hospital in the UK between August 2021 and March 2022. Diagnosis was based on a combination of clinical signs, laboratory, imaging and cytological findings, and immunocytochemistry. Twenty cats presented with effusive FIP and 5 cats with non-effusive FIP. Five cats had neurological signs and 4 cats had significant ocular involvement. At the time of writing, 10 cats had successfully completed an 84-day course of remdesivir and GS-441524 treatment with complete clinical and biochemical remission. Ten cats were in clinical remission and still receiving treatment and 5 cats were euthanised a median of 2 days (range 1-13) after starting treatment. All surviving cats received remdesivir intravenously for a median of 5 days (range 2-9) at a median dose of 15 mg/kg (range 10-20). Higher doses were used for cats with non-effusive FIP, neurological or ocular signs, and for effusive cases presenting with severe clinical signs. All 20 cats demonstrated significant clinical response after a median of 2 days (range 2-5). Two cats received subcutaneous remdesivir treatment only following initial intravenous therapy. Eight cats received subcutaneous remdesivir for a median of 14 days (range 4-68) before transitioning onto an equivalent dose of oral GS- 441524. Ten cats received oral GS-441524 treatment immediately following intravenous remdesivir therapy. Both drugs were well tolerated although local skin reactions and pain with subcutaneous injections of remdesivir was observed. Of the five cats that were euthanised, three cats were euthanised within 3 days of starting treatment as a result of comorbidities or financial constraints. One ragdoll developed a T3-L3 myelopathy 7 days into treatment with 15mg/kg remdesivir, with no clinical improvement following dose escalation. Post-mortem confirmed FIP within the central nervous system. Another ragdoll also developed central nervous system signs 13 days into treatment with 20mg/kg remdesivir and was subsequently euthanised. This case series demonstrated the successful use of injectable remdesivir and oral GS-441524 for the treatment of FIP in 20 out of 25 (80%) cats.

In Vitro Suppression of Feline Infectious Peritonitis Virus Infection by Ribonucleoside Analog Eidd-1931

The ribonucleoside analog EIDD-1931 is an RNA polymerase inhibitor and a broad-spectrum antiviral nucleotide that has been shown to inhibit replication of RNA viruses such as hepatitis C virus, Ebola virus, and human and animal coronaviruses. To assess the ability of EIDD-1931 to suppress feline infectious peritonitis virus (FIPV) replication in vitro, a feline macrophage cell line (fcwf-4) was infected with FIPV for 2 h and exposed to a range of EIDD-1931 concentrations, and the cells were cultured with agarose overlays for 96 h before using visual cell imaging to quantitate reduction in viral cytopathic effects (CPEs). An IncuCyte (Sartorius, Essen BioScience, USA) instrument was used to quantify cell confluence after fixation and crystal violet staining. The results showed that 100 nM and 10 nM concentrations of EEID-1931 significantly reduced the viral CPEs when compared with infected cultures without the drug (Figure 1). In addition, these drug concentrations were not cytopathic to the cultured fcwf-4 cells. Based on these findings: (1) the ribonucleoside analog EIDD-1931 is effective at suppressing FIPV replication in cells;and (2) the drug does not kill fcwf-4 cells at concentrations with strong antiviral activity. Thus, EIDD-1931 warrants further evaluation as a new agent for treatment of FIP in cats.

Effect of GS-441524 in combination with the 3C-like protease inhibitor GC376 on the treatment of naturally transmitted feline infectious peritonitis.

Objectives: The main objectives of this study were to investigate the efficacy of the nucleotide analog GS-441524 in combination with the 3C-like protease inhibitor GC376 for the treatment of naturally aquired feline infectious peritonitis (FIP) and to test whether their combination shortens the dosing period and improves the cure rate. Methods: In total, 46 FIP-affected cats were enrolled in this experiment, including 36 with wet FIP (29 with abdominal effusion, six with thoracic effusion, and one with thoracic+abdominal effusion), and 10 with dry FIP. The cats were aged from 3 to 96 months. Thoracic+abdominal effusion, lymph-node puncture fluid and perirenal puncture fluid was collected from the affected cats for qPCR testing, and all 46 cats were positive for feline coronavirus (FCoV). The cats divided into different dose groups, all treated for 4 weeks: group 1 (GS-441524, 5 mg/kg.sc.q.24 h; GC376, 20 mg/kg.sc.q.12 h), group 2 (GS-441524, 2.5 mg/kg.sc.q.24 h; GC376, 20 mg/kg.sc.q.12 h), group 3 (GS-441524, 2.5 mg/kg.sc.q.24 h; GC376, 10 mg/kg.sc.q.12 h), and group 4 (GS-441524, 5 mg/kg.sc.q.24 h; GC376, 10 mg/kg.sc.q.12 h). Results: After the 4-week combination treatment, 45 of the 46 (97.8%) cats survived, and 43 of those became clinically normal. Two cats required longer (7 to 12 weeks) treatment to achieve full recovery. As of writing (10 months after completion of the trial), all 45 cats were alive and no relapse was observed. Conclusions and relevance: GS-441524 combined with GC376 can be safely and effectively used to treat FIP and reduces the treatment period to 4 weeks, with an excellent cure rate.

An Optimized Bioassay for Screening Combined Anticoronaviral Compounds for Efficacy against Feline Infectious Peritonitis Virus with Pharmacokinetic Analyses of GS-441524, Remdesivir, and Molnupiravir in Cats.

Feline infectious peritonitis (FIP) is a fatal disease of cats that currently lacks licensed and affordable vaccines or antiviral therapeutics. The disease has a spectrum of clinical presentations including an effusive ("wet") form and non-effusive ("dry") form, both of which may be complicated by neurologic or ocular involvement. The feline coronavirus (FCoV) biotype, termed feline infectious peritonitis virus (FIPV), is the etiologic agent of FIP. The objective of this study was to determine and compare the in vitro antiviral efficacies of the viral protease inhibitors GC376 and nirmatrelvir and the nucleoside analogs remdesivir (RDV), GS-441524, molnupiravir (MPV; EIDD-2801), and ß-D-N4-hydroxycytidine (NHC; EIDD-1931). These antiviral agents were functionally evaluated using an optimized in vitro bioassay system. Antivirals were assessed as monotherapies against FIPV serotypes I and II and as combined anticoronaviral therapies (CACT) against FIPV serotype II, which provided evidence for synergy for selected combinations. We also determined the pharmacokinetic properties of MPV, GS-441524, and RDV after oral administration to cats in vivo as well as after intravenous administration of RDV. We established that orally administered MPV at 10 mg/kg, GS-441524 and RDV at 25 mg/kg, and intravenously administered RDV at 7 mg/kg achieves plasma levels greater than the established corresponding EC50 values, which are sustained over 24 h for GS-441514 and RDV.

Short- and Long-Term Outcomes of Unlicensed Gs-441524-Like Antiviral Therapy at-Home Treatment of Feline Infectious Peritonitis

Introduction: Prognosis of cats with feline infectious peritonitis (FIP), hitherto an invariably fatal disease, has purportedly improved with the introduction of the unlicensed nucleoside analog GS-441524 (GS). Method(s): A prospective observational study. Inclusion criteria comprised a complete medical record, characteristic clinical signs and laboratory changes, and a confirmatory RT-PCR test for the presence of feline coronavirus and FIP pathogenic strains in pleural/peritoneal/cerebrospinal fluid samples. Clinical signs, laboratory parameters, and adverse effects were recorded at diagnosis, during treatment, and at the end of a 12-week observation period. Remission was defined as completion of 12 weeks or more of treatment and resolution of clinical signs. Result(s): Overall, 175 medical files were reviewed but only 38 cases met the inclusion criteria. Samples of used vials were analyzed by high-performance liquid chromatography and identified GS-441524 as the active component. Twenty-one cats (55%) were considered in full remission, 7 (18 %) cats are currently treated, and 4 cats are in the 12-week observation period. Two cats experienced a relapse, 1 and 6 weeks after completion of treatment. Six (15%) cats died. Anemia (65%), jaundice (50%), thrombocytopenia (50%), and an albumin globulin ratio under 0.6 (81%) were common findings. Clinical manifestation included effusive (n = 30), noneffusive (n = 3), and neurological (n = 6) forms. Adverse effects included injection site reactions (52% of cats) and pain (95% of cats), and temporary creatinine increase (64%). Conclusion(s): Short-term efficacy against FIP disease, using an unlicensed nucleotide analog, was observed herein. The unknown purity or biological activity of these unlicensed compounds is a major limitation of this treatment.

Updates on Coronavirus-Related Ocular Manifestations: From the Past to COVID-19 Pandemic

Context: Coronaviruses are the largest RNA viruses associated with some ocular manifestations. There are various contradictory reports about the ocular manifestations of coronaviruses in humans. Different ocular tissues can affect coronavirus-associated infectious diseases. Evidence Acquisition: All manuscripts were collected from PubMed, Google Scholar, and other relevant databases. All searches were done by specific keywords, including "coronavirus," "ocular disease," and "eye." Results: There are various contradictory reports about the ocular effects of coronaviruses in humans. Different ocular tissues are involved in coronavirus-associated infectious diseases. The ductal connection between the upper respiratory tract and eye mucosa through the nasolacrimal duct can be an entrance to respiratory viruses, such as coronaviruses. The coronavirus can infect the retina, conjunctiva, cornea, and uvea of the eye. The primary SARS-CoV-2 receptor, ACE2, is mainly expressed in the posterior tissues of the eye, such as the retina and RPE. Feline CoV, SARS-CoV, MERS-CoV, and infectious bronchitis virus (IBV) are responsible for conjunctiva involvement in coronavirus-related ocular pathogenesis. Also, various studies are held on COVID-19 and the impact of the conjunctiva on diagnosis and medical complications. Given that the cornea has an acceptable expression of ACE2 and TMPRSS2 genes compared to lung tissue, some studies were done on the impact of the cornea in COVID-19. Feline infectious peritonitis virus (FIPV) is also related to uvea complications. The experiments of human and animal models on the effects of coronaviruses on the retina and cornea in the event of various epidemics of coronaviruses and new and unknown ocular complications can be of great help to future studies. Conclusions: Given the importance of investigating the pathogenesis and other routes of SARS-CoV-2 infection, especially in areas other than the respiratory tract, this report attempts to highlight the importance of eye infections caused by the virus, its role in maintaining the virus transmission chain, and its impact on public health.

Relationship between Uveal Inflammation and Viral Detection in 30 Cats with Feline Infectious Peritonitis.

Feline infectious peritonitis (FIP) virus is the most common infectious cause of uveitis in cats. Confirmatory diagnosis is usually only reached at postmortem examination. The relationship between the histologic inflammatory pattern, which depends on the stage of the disease, and the likelihood of detection of the viral antigen and/or RNA has not been investigated. We hypothesized that viral detection rate by either immunohistochemistry, in situ hybridization or RT-qPCR is dependent upon the predominant type of uveal inflammatory response (i.e., pyogranulomatous vs. plasmacytic). Thus, the aims of this study were to evaluate cases of FIP-induced uveitis, localize the viral antigen and RNA, and assess the relationship between the inflammatory pattern (macrophage- vs. plasma cell-rich) and the likelihood of detecting the FIP antigen and/or RNA. We evaluated 30 cats with FIP-induced uveitis. The viral antigen and/or RNA were detected within uveal macrophages in 11/30 cases, of which 8 tested positive by RT-qPCR. Correlation analysis determined a weak to moderate but significant negative correlation between the degree of plasmacytic uveal inflammation and the likelihood of detecting the FIP antigen and RNA. This study suggests that predominance of plasmacytic inflammation in cases of FIP uveitis reduces the odds of a confirmatory diagnosis through the viral detection methods available.

Feline infectious peritonitis (FIP): a case report

A male Munchkin cat was brought to a small animal teaching hospital at Mahanakorn University of Technology. The patient presentation with vomiting, chronic diarrhea, and intermittent fever. From history-taking, the owner previously had a cat that was diagnosed with feline infectious peritonitis (FIP) living in the same house but had isolated in a separate area. Fecal examination revealed bacterial enteritis. Hematology and blood chemistry results shown lymphopenia, hypoalbuminemia, and low serum albumin/globulin ratio (0.3 A: G ratio). Abdominal ultrasound revealed mesenteric lymph node (MLN) enlargement and cholecystitis. Cell cytology from the liver and MLN revealed suppurative inflammation. Reverse transcription PCR (RT-PCR) was negative for the Feline coronavirus (FCoV) in the blood sample. On the 4th day of treatment, the cat developed pleural and peritoneal effusion. Thoracentesis and abdominocentesis were performed and submitted for analysis. The fluid's results were classified as modified transudate, low A: G ratio (0.3), Rivalta's test (positive), and positive for FCoV by using RT-PCR. On the 8th day of treatment, the cat died from systemic hypotension. Viscous straw yellow-colored fluid and pyogranulomatous lesions at the liver, lung, kidney, and MLN were observed from the necropsy. Histopathology's results shown severe suppurative inflammation in all the above organs. FIP was confirmed by detected FCoV antigen in the cytoplasm of macrophages in the kidney and lung tissue by immunohistochemistry staining.

Isolation and Molecular Detection of Feline Infectious Peritonitis Virus

Feline coronavirus (FCoV) is an enveloped single-stranded RNA virus, affecting wild and domestic cats. Feline infectious peritonitis viruses (FIPV) variants of FCoV cause fatal peritonitis affecting approximately 5% of FCoV infected animals. The present study aimed to detect and isolate the feline infectious peritonitis virus for the first time in Iraq. In this study, 50 samples (fecal swab and peritoneal fluid) were collected from suspected pet cats from different areas of Baghdad, Iraq. The very suitable age was under two years old. Real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) was used to detect Feline infectious peritonitis in infected collected samples by the amplification of spike protein (S). The result of real-time RT-PCR revealed that out of 50 samples from suspected cats, 10 samples were positive for FIPV. Moreover, 10 positive samples by real-time RT-PCR were used for the isolation of the virus in chicken embryo fibroblast cell culture. Subsequently, the isolated virus was detected by real-time RT-PCR and then by conventional RT-PCR, followed by electrophoresis.

Electrophorsis:indications and uses

In this article the author discusses how electrophoresis can aid in the diagnosis and treatment of inflammatory and infectious diseases in animals such as feline infectious peritonitis, Leishmania infantum and neoplasms.

Development of Colorimetric Reverse Transcription Loop-Mediated Isothermal Amplification Assay for Detecting Feline Coronavirus.

Feline infectious peritonitis (FIP) is a worldwide fatal disease caused by a mutant feline coronavirus (FCoV). Simple and efficient molecular detection methods are needed. Here, sensitive, specific, rapid, and reliable colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) was developed to detect the ORF1a/1b gene of FCoV from cats with suspected FIP using neutral red as an indicator. Novel LAMP primers were specifically designed based on the gene of interest. The isothermal assay could visually detect FCoV at 58 °C for 50 min. The RT-LAMP assay was highly specific and had no cross-reactivity with other related feline viruses. The detection limit of FCoV detection by RT-LAMP was 20 fg/µL. A blind clinical test (n = 81) of the developed RT-LAMP procedure was in good agreement with the conventional PCR method. In the light of its performance specificity, sensitivity, and easy visualization, this neutral-red-based RT-LAMP approach would be a fruitful alternative molecular diagnostic tool for veterinary inspection of FCoV when combined with nucleotide sequencing or specific PCR to affirm the highly virulent FIP-associated FCoV.

Ionophore Antibiotics Inhibit Type II Feline Coronavirus Proliferation In Vitro.

Feline coronaviruses (FCoVs) infect cats worldwide and cause severe systemic diseases, such as feline infectious peritonitis (FIP). FIP has a high mortality rate, and drugs approved by the Food and Drug Administration have been ineffective for the treatment of FIP. Investigating host factors and the functions required for FCoV replication is necessary to develop effective drugs for the treatment of FIP. FCoV utilizes an endosomal trafficking system for cellular entry after binding between the viral spike (S) protein and its receptor. The cellular enzymes that cleave the S protein of FCoV to release the viral genome into the cytosol require an acidic pH optimized in the endosomes by regulating cellular ion concentrations. Ionophore antibiotics are compounds that form complexes with alkali ions to alter the endosomal pH conditions. This study shows that ionophore antibiotics, including valinomycin, salinomycin, and nigericin, inhibit FCoV proliferation in vitro in a dose-dependent manner. These results suggest that ionophore antibiotics should be investigated further as potential broad-spectrum anti-FCoV agents.

Genomic and phylogenetic analysis of the ORF7b gene from a Chinese feline infectious peritonitis virus isolate

FCoV viruses exhibit great genetic diversity, leading to the presence of FIPV-causing variants. Current molecular evolution analysis and genetic variation studies of FCoV in China are predominately focused on gene encoding the spike protein or other structural proteins, while few studies have evaluated genetic variations in nonstructural FCoV genes, which can play an important role in disease pathogenesis. In this study, the gene encoding the open reading frame (ORF) 7b nonstructural FCoV protein of the Chinese Fujian strain FJLY20201 was amplified from the ascitic fluid of a Chinese domestic cat infected with FIPV and compared with ORF 7b from previously published FCoV strains. Multiple sequence alignment revealed that FJLY20201 exhibited high identity with other Chinese FCoV strains. Phylogenetic analyses indicated that the Chinese strains did not differentiate between type I and type II serotypes of FCoV based on S proteins. In addition, they formed clades and differed genetically from strains originating outside China. This study provides the molecular epidemiology data about the ORF 7b genes of FCoV strains in China. Our results show that the identity of ORF 7b genes was closer between the Chinese isolates, and suggest that variation in ORF 7b is more dependent on geographical origin.

Feline Coronavirus and Feline Infectious Peritonitis

While feline coronaviruses (FCoV) are ubiquitous in cat populations, the incidence of feline infectious peritonitis (FIP) remains low;nonetheless, the disease can be devastating for cat owners and shelter personnel. FIP is often challenging to diagnose, affects highly adoptable kittens and young cats, and creates prognostic uncertainty for healthy siblings of affected cats. FCoV is an enteric pathogen of cats that is often endemic in shelters and other multi-cat environments. Infection with FCoV generally occurs through fecal-oronasal transmission, most commonly through shared litterboxes contaminated with the virus. In some cases, more virulent strains of FCoV result in more severe FECV-related disease or an increased likelihood of mutation to FIPV. In others, the stress or immune status of the host plays a role in both decreased immune response and increased levels of shedding. © 2021 John Wiley & Sons, Inc. All rights reserved.