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22 pages, 3091 KiB

Open AccessArticle

Colony Stimulating Factors in Early Feline Infectious Peritonitis Virus Infection of Monocytes and in End Stage Feline Infectious Peritonitis; A Combined In Vivo And In Vitro Approach

by Alexandra J. Malbon, Eleni Michalopoulou, Marina L. Meli, Emi N. Barker, Séverine Tasker, Keith Baptiste and Anja Kipar

Pathogens 2020, 9(11), 893; https://0-doi-org.brum.beds.ac.uk/10.3390/pathogens9110893 - 27 Oct 2020

Cited by 7 | Viewed by 2759

Abstract

Feline coronavirus (FCoV) infection initiates monocyte-associated viremia and viral persistence. Virus-infected, -activated monocytes also trigger feline infectious peritonitis (FIP), a fatal systemic disease of felids typified by granulomatous (peri)phlebitis. Currently, the exact mechanisms inducing monocyte activation and FIP are unknown. This study attempted [...] Read more.

Feline coronavirus (FCoV) infection initiates monocyte-associated viremia and viral persistence. Virus-infected, -activated monocytes also trigger feline infectious peritonitis (FIP), a fatal systemic disease of felids typified by granulomatous (peri)phlebitis. Currently, the exact mechanisms inducing monocyte activation and FIP are unknown. This study attempted to identify the potential immediate effect of virulent FCoV on colony-stimulating factor (CSF) (granulocyte (G)-CSF, monocyte (M)-CSF and granulocyte-monocyte (GM)-CSF levels through in vitro assessment, alongside prototypical pro- and anti-inflammatory mediators (interleukin (IL)-1, IL-6, IL-12p40, tumor necrosis factor (TNF)-α, and IL-10); this was assessed alongside the in vivo situation in the hemolymphatic tissues of cats euthanized with natural end-stage FIP. For the in vitro work, isolated monocytes from SPF cats were cultured short-term and infected with the FIP virus (FIPV) strain DF2. Mediator transcription was assessed by quantitative reverse transcriptase PCR (RT-qPCR) at 3, 6 and 9 h post infection (hpi), and in the post-mortem samples of bone marrow, spleen, and mesenteric lymph nodes (MLN) of cats with FIP. We observed limited and transient changes in cytokine transcription in monocytes after infection, i.e., a significant increase of IL-6 at 3 hpi and of GM-CSF over the 3 and 6 hpi period, whereas M-CSF was significantly decreased at 9 hpi, with a limited effect of age. The findings indicate that the infection induces expansion of the monocyte/macrophage population, which would ensure the sufficient supply of cells for consistent viral replication. In natural disease, the only upregulation was of G-CSF in the MLN, suggesting either immune exhaustion or an active downregulation by the host as part of its viral response. Full article

(This article belongs to the Special Issue Feline Infectious Peritonitis)

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9 pages, 2189 KiB

Open AccessEditor’s ChoiceArticle

Detection of Feline Coronavirus in Feline Effusions by Immunofluorescence Staining and Reverse Transcription Polymerase Chain Reaction

by Yi-Chen Luo, I-Li Liu, Yu-Tan Chen and Hui-Wen Chen

Pathogens 2020, 9(9), 698; https://0-doi-org.brum.beds.ac.uk/10.3390/pathogens9090698 - 25 Aug 2020

Cited by 5 | Viewed by 3950

Abstract

Feline coronavirus (FCoV), the pathogen for feline infectious peritonitis, is a lethal infectious agent that can cause effusions in the pleural and abdominal cavities in domestic cats. To study the epidemiology of FCoV in Taiwan, 81 FIP-suspected sick cats with effusive specimens were [...] Read more.

Feline coronavirus (FCoV), the pathogen for feline infectious peritonitis, is a lethal infectious agent that can cause effusions in the pleural and abdominal cavities in domestic cats. To study the epidemiology of FCoV in Taiwan, 81 FIP-suspected sick cats with effusive specimens were recruited to test for FCoV infection using immunofluorescence staining and reverse transcription-polymerase chain reaction as detection methods, and viral RNAs were recovered from the specimens to conduct genotyping and phylogenetic analysis based on the spike (S) protein gene. The results revealed that a total of 47 (47/81, 58%) of the sick cats were positive for FCoV in the effusion samples, of which 39 were successfully sequenced and comprised of 21 type I strains, 9 type II strains, and 9 co-infections. The signalment analysis of these sick cats revealed that only the sex of cats showed a significant association (odds ratio = 2.74, 95% confidence interval = 1.06–7.07, p = 0.03) with the infection of FCoV, while age and breed showed no association. FCoV-positive cats demonstrated a significantly lower albumin to globulin ratio than negative individuals (p = 0.0004). The partial S gene-based phylogenetic analysis revealed that the type I strains demonstrated genetic diversity forming several clades, while the type II strains were more conserved. This study demonstrates the latest epidemiological status of FCoV infection in the northern part of Taiwan among sick cats and presents comparisons of Taiwan and other countries. Full article

(This article belongs to the Special Issue Feline Infectious Peritonitis)

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20 pages, 2228 KiB

Open AccessArticle

FCoV Viral Sequences of Systemically Infected Healthy Cats Lack Gene Mutations Previously Linked to the Development of FIP

by Mirjam Lutz, Aline R. Steiner, Valentino Cattori, Regina Hofmann-Lehmann, Hans Lutz, Anja Kipar and Marina L. Meli

Pathogens 2020, 9(8), 603; https://0-doi-org.brum.beds.ac.uk/10.3390/pathogens9080603 - 24 Jul 2020

Cited by 9 | Viewed by 4397

Abstract

Feline Infectious Peritonitis (FIP)—the deadliest infectious disease of young cats in shelters or catteries—is induced by highly virulent feline coronaviruses (FCoVs) emerging in infected hosts after mutations of less virulent FCoVs. Previous studies have shown that some mutations in the open reading frames [...] Read more.

Feline Infectious Peritonitis (FIP)—the deadliest infectious disease of young cats in shelters or catteries—is induced by highly virulent feline coronaviruses (FCoVs) emerging in infected hosts after mutations of less virulent FCoVs. Previous studies have shown that some mutations in the open reading frames (ORF) 3c and 7b and the spike (S) gene have implications for the development of FIP, but mainly indirectly, likely also due to their association with systemic spread. The aim of the present study was to determine whether FCoV detected in organs of experimentally FCoV infected healthy cats carry some of these mutations. Viral RNA isolated from different tissues of seven asymptomatic cats infected with the field strains FCoV Zu1 or FCoV Zu3 was sequenced. Deletions in the 3c gene and mutations in the 7b and S genes that have been shown to have implications for the development of FIP were not detected, suggesting that these are not essential for systemic viral dissemination. However, deletions and single nucleotide polymorphisms leading to truncations were detected in all nonstructural proteins. These were found across all analyzed ORFs, but with significantly higher frequency in ORF 7b than ORF 3a. Additionally, a previously unknown homologous recombination site was detected in FCoV Zu1. Full article

(This article belongs to the Special Issue Feline Infectious Peritonitis)

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13 pages, 789 KiB

Open AccessEditor’s ChoiceArticle

Correlation of Feline Coronavirus Shedding in Feces with Coronavirus Antibody Titer

by Sandra Felten, Ute Klein-Richers, Regina Hofmann-Lehmann, Michèle Bergmann, Stefan Unterer, Christian M. Leutenegger and Katrin Hartmann

Pathogens 2020, 9(8), 598; https://0-doi-org.brum.beds.ac.uk/10.3390/pathogens9080598 - 22 Jul 2020

Cited by 28 | Viewed by 4972

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Feline Infectious Peritonitis)

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8 pages, 221 KiB

Open AccessArticle

Evaluation of Interferon-Gamma Polymorphisms as a Risk Factor in Feline Infectious Peritonitis Development in Non-Pedigree Cats—A Large Cohort Study

by Emi N. Barker, Philippa Lait, Lorenzo Ressel, Emily-Jayne Blackwell, Séverine Tasker, Helen Kedward-Dixon, Anja Kipar and Christopher R. Helps

Pathogens 2020, 9(7), 535; https://doi.org/10.3390/pathogens9070535 - 03 Jul 2020

Cited by 7 | Viewed by 2973

Abstract

Feline infectious peritonitis (FIP) is a common infectious cause of death in cats, with heritable host factors associated with altered risk of disease. To assess the role of feline interferon-gamma gene (fIFNG) variants in this risk, the allele frequencies of two [...] Read more.

Feline infectious peritonitis (FIP) is a common infectious cause of death in cats, with heritable host factors associated with altered risk of disease. To assess the role of feline interferon-gamma gene (fIFNG) variants in this risk, the allele frequencies of two single nucleotide polymorphisms (SNPs) (g.401 and g.408) were determined for non-pedigree cats either with confirmed FIP (n = 59) or from the general population (cats enrolled in a large lifetime longitudinal study; n = 264). DNA was extracted from buccal swabs or tissue samples. A pyrosequencing assay to characterize the fIFNG SNPs was designed, optimized and subsequently performed on all samples. Genotype and allele frequency were calculated for each population. Characterization of the target SNPs was possible for 56 of the cats with FIP and 263 of the cats from the general population. The SNPs were in complete linkage disequilibrium with each other. There was an association between FIP status and genotype (χ²; p = 0.028), with a reduced risk of developing FIP (χ²; p = 0.0077) associated with the genotype TT at both positions. These results indicate that, although fIFNG variants may be associated with altered risk of disease, the prevalence of individual variants within both populations limits application of their characterization to breeding purposes. Full article

(This article belongs to the Special Issue Feline Infectious Peritonitis)

19 pages, 724 KiB

Open AccessArticle

The Effect of Natural Feline Coronavirus Infection on the Host Immune Response: A Whole-Transcriptome Analysis of the Mesenteric Lymph Nodes in Cats with and without Feline Infectious Peritonitis

by Alexandra J. Malbon, Giancarlo Russo, Carole Burgener, Emi N. Barker, Marina L. Meli, Séverine Tasker and Anja Kipar

Pathogens 2020, 9(7), 524; https://0-doi-org.brum.beds.ac.uk/10.3390/pathogens9070524 - 29 Jun 2020

Cited by 7 | Viewed by 4152

Abstract

Feline infectious peritonitis (FIP) is a coronavirus-induced disease of cats, in which the immune system is known to play a crucial, but complex, role in the pathogenesis. This role is still incompletely understood, with involvement of both host and viral factors. To evaluate [...] Read more.

Feline infectious peritonitis (FIP) is a coronavirus-induced disease of cats, in which the immune system is known to play a crucial, but complex, role in the pathogenesis. This role is still incompletely understood, with involvement of both host and viral factors. To evaluate differential gene expression and pathway involvement in feline coronavirus (FCoV) infection and FIP, we applied next-generation RNA-sequencing of the mesenteric lymph nodes from cats with naturally-acquired FIP, as well as those with systemic FCoV infection without FIP, and those with neither. Viral infection was associated with upregulation of viral defenses regardless of the disease state, but to a greater degree in FIP. FIP was associated with higher pro-inflammatory pathway enrichment, whilst non-FIP FCoV-positive cats showed lower enrichment of humoral immunity pathways, below that of uninfected cats in the case of immunoglobulin production pathways. This host response is presumed to be protective. In FIP, downregulation of T cell-related processes was observed, which did not occur in non-FIP FCoV-positive cats. These results emphasize the importance of the host’s immune balance in determining the outcome of the FCoV infection. Full article

(This article belongs to the Special Issue Feline Infectious Peritonitis)

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12 pages, 2595 KiB

Open AccessArticle

Cellular Metabolic Profiling of CrFK Cells Infected with Feline Infectious Peritonitis Virus Using Phenotype Microarrays

by Shing Wei Ng, Gayathri Thevi Selvarajah, Yoke Kqueen Cheah, Farina Mustaffa Kamal and Abdul Rahman Omar

Pathogens 2020, 9(5), 412; https://0-doi-org.brum.beds.ac.uk/10.3390/pathogens9050412 - 25 May 2020

Cited by 4 | Viewed by 3668

Abstract

Feline infectious peritonitis (FIP) is a fatal feline immune-mediated disease caused by feline infectious peritonitis virus (FIPV). Little is known about the biological pathways associated in FIP pathogenesis. This is the first study aiming to determine the phenotypic characteristics on the cellular level [...] Read more.

Feline infectious peritonitis (FIP) is a fatal feline immune-mediated disease caused by feline infectious peritonitis virus (FIPV). Little is known about the biological pathways associated in FIP pathogenesis. This is the first study aiming to determine the phenotypic characteristics on the cellular level in relation to specific metabolic pathways of importance to FIP pathogenesis. Methods: The internalization of type II FIPV WSU 79-1146 in Crandell-Rees Feline Kidney (CrFK) cells was visualized using a fluorescence microscope, and optimization prior to phenotype microarray (PM) study was performed. Then, four types of Biolog Phenotype MicroArray™ plates (PM-M1 to PM-M4) precoated with different carbon and nitrogen sources were used to determine the metabolic profiles in FIPV-infected cells. Results: The utilization of palatinose was significantly low in FIPV-infected cells; however, there were significant increases in utilizing melibionic acid, L-glutamine, L-glutamic acid and alanyl-glutamine (Ala-Gln) compared to non-infected cells. Conclusion: This study has provided the first insights into the metabolic profiling of a feline coronavirus infection in vitro using PMs and deduced that glutamine metabolism is one of the essential metabolic pathways for FIPV infection and replication. Further studies are necessary to develop strategies to target the glutamine metabolic pathway in FIPV infection. Full article

(This article belongs to the Special Issue Feline Infectious Peritonitis)

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12 pages, 3579 KiB

Open AccessEditor’s ChoiceArticle

In Vivo Antiviral Effects of U18666A Against Type I Feline Infectious Peritonitis Virus

by Tomoyoshi Doki, Tomoyo Tarusawa, Tsutomu Hohdatsu and Tomomi Takano

Pathogens 2020, 9(1), 67; https://0-doi-org.brum.beds.ac.uk/10.3390/pathogens9010067 - 18 Jan 2020

Cited by 15 | Viewed by 4713

Abstract

Background: The cationic amphiphilic drug U18666A inhibits the proliferation of type I FIPV in vitro. In this study, we evaluated the in vivo antiviral effects of U18666A by administering it to SPF cats challenged with type I FIPV. Methods: Ten SPF cats were [...] Read more.

Background: The cationic amphiphilic drug U18666A inhibits the proliferation of type I FIPV in vitro. In this study, we evaluated the in vivo antiviral effects of U18666A by administering it to SPF cats challenged with type I FIPV. Methods: Ten SPF cats were randomly assigned to two experimental groups. FIPV KU-2 were inoculated intraperitoneally to cats. The control group was administered PBS, and the U18666A-treated group was administered U18666A subcutaneously at 2.5 mg/kg on day 0, and 1.25 mg/kg on days 2 and 4 after viral inoculation. Results: Two of the five control cats administered PBS alone developed FIP. Four of the five cats administered U18666A developed no signs of FIP. One cat that temporarily developed fever, had no other clinical symptoms, and no gross lesion was noted on an autopsy after the end of the experiment. The FIPV gene was detected intermittently in feces and saliva regardless of the development of FIP or administration of U18666A. Conclusions: When U18666A was administered to cats experimentally infected with type I FIPV, the development of FIP might be suppressed compared with the control group. However, the number of animals with FIP is too low to establish anti-viral effect of U18666A in cats. Full article

(This article belongs to the Special Issue Feline Infectious Peritonitis)

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13 pages, 4673 KiB

Open AccessEditor’s ChoiceArticle

Endocytic Pathway of Feline Coronavirus for Cell Entry: Differences in Serotype-Dependent Viral Entry Pathway

by Tomomi Takano, Yumeho Wakayama and Tomoyoshi Doki

Pathogens 2019, 8(4), 300; https://0-doi-org.brum.beds.ac.uk/10.3390/pathogens8040300 - 16 Dec 2019

Cited by 14 | Viewed by 7231

Abstract

Feline coronavirus (FCoV) is a pathogen causing a lethal infectious disease in cats, feline infectious peritonitis. It has two serotypes (type I FCoV and type II FCoV). According to our previous study, type I FCoV infection is inhibited by compounds inducing intracellular cholesterol [...] Read more.

Feline coronavirus (FCoV) is a pathogen causing a lethal infectious disease in cats, feline infectious peritonitis. It has two serotypes (type I FCoV and type II FCoV). According to our previous study, type I FCoV infection is inhibited by compounds inducing intracellular cholesterol accumulation, whereas type II FCoV infection is not inhibited. Intracellular cholesterol accumulation was reported to disrupt late endosome function. Based on these findings, types I and II FCoV are considered to enter the cytosol through late and early endosomes, respectively. We investigated whether the antiviral activities of a late endosome trafficking inhibitor and cholesterol-accumulating agents are different between the FCoV serotypes. The late endosome trafficking inhibitor did not inhibit type II FCoV infection, but it inhibited type I FCoV infection. Type I FCoV infection was inhibited by cholesterol-accumulating triazoles, but not by non-cholesterol-accumulating triazoles. These phenomena were observed in both feline cell lines and feline primary macrophages. This study provides additional information on the differences in intracellular reproductive cycle between type I and type II FCoV. Full article

(This article belongs to the Special Issue Feline Infectious Peritonitis)

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