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1.
Previous studies have demonstrated that the concentration of alpha1-acid glycoprotein (AGP) transiently increases in asymptomatic cats infected with feline coronavirus (FCoV). In order to establish whether these fluctuations depend on the FCoV status, the serum concentration of AGP and anti-FCoV antibody titres and/or faecal shedding of FCoVs in clinically healthy cats from catteries with different levels of prevalence of FCoV infection were monitored over time. Serum AGP concentrations fluctuated over time in clinically healthy cats from the cattery with the highest prevalence of feline infectious peritonitis (FIP) and significantly increased just before an outbreak of FIP. Further studies are required to clarify whether the observed increase of AGP concentration is a consequence of the increased viral burden or a protective response against mutated viral strains. Nevertheless, the results of the present study suggest that AGP might be useful in monitoring FCoV-host interactions in FCoV-endemic catteries.  相似文献   

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Feline infectious peritonitis (FIP) infection resulting in clinical signs is invariably fatal despite clinical intervention. As FIP is an immune-mediated disease, treatment is mainly aimed at controlling the immune response triggered by the infection with the feline coronavirus (FCoV). Immune suppressive drugs such as prednisone or cyclophosphamide may slow disease progression but do not produce a cure. In nearly every published case report of attempted therapy for clinical FIP, glucocorticoids have been used; there are, however, no controlled studies that evaluate the effect of glucocorticoids as a therapy for FIP. Some veterinarians prescribe immune modulators to treat cats with FIP with no documented controlled evidence of efficacy. It has been suggested that these agents may benefit infected animals by restoring compromised immune function, thereby allowing the patient to control viral burden and recover from clinical signs. However, a non-specific stimulation of the immune system may be contraindicated as clinical signs develop and progress as a result of an immune-mediated response to the mutated FCoV.  相似文献   

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The aim of this study was to quantify and compare interferon-γ (IFN-γ) concentrations in the serum of clinically normal cats infected with feline coronavirus (FCoV) with its concentration in the sera and effusions of cats with feline infectious peritonitis (FIP), a disease associated with infection with a mutated form of FCoV.Clinically normal FCoV-infected cats living in catteries with a high prevalence of FIP had the highest serum IFN-γ concentrations. The serum concentration of IFN-γ was not significantly different in cats with FIP compared with clinically normal FCoV-infected animals living in catteries with a low prevalence of the disease. Moreover, the concentration of IFN-γ was significantly higher in the effusions than in the serum of cats with FIP, probably due to IFN-γ production within lesions. These findings support the hypothesis that there is a strong, ‘systemic’ cell mediated immune response in clinically normal, FCoV-infected cats and that a similar process, albeit at a tissue level, is involved in the pathogenesis of FIP.  相似文献   

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A closed household of 26 cats in which feline coronavirus (FCoV), feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV) were endemic was observed for 10 years. Each cat was seropositive for FCoV on at least one occasion and the infection was maintained by reinfection. After 10 years, three of six surviving cats were still seropositive. Only one cat, which was also infected with FIV, developed feline infectious peritonitis (FIP). Rising anti-FCoV antibody titres did not indicate that the cat would develop FIP. The FeLV infection was self-limiting because all seven of the initially viraemic cats died within five years and the remainder were immune. However, FeLV had the greatest impact on mortality. Nine cats were initially FIV-positive and six more cats became infected during the course of the study, without evidence of having been bitten. The FIV infection did not adversely affect the cats' life expectancy.  相似文献   

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To assess whether alpha‐1‐acid glycoprotein (AGP) can be detected on the membrane of feline circulating leucocytes. Design The presence of AGP on circulating leucocytes was investigated in both clinically healthy cats and cats with different diseases. A group of feline coronavirus (FCoV)‐positive cats, comprising cats with feline infectious peritonitis (FIP) and cats not affected by FIP but seropositive for FCoV, were included in this study because the serum concentration of AGP increases during FCoV infection. Procedure Flow cytometry (using an anti‐feline AGP antibody), serum protein electrophoresis, routine haematology and measurement of the serum AGP concentration were performed using blood samples from 32 healthy cats (19 FCoV‐seropositive), 13 cats with FIP and 12 with other diseases (6 FCoV‐seropositive). The proportion of cats with AGP‐positive leucocytes in the different groups (e.g. controls vs sick; FIP vs other diseases, etc.) or in cats with different intensities of inflammatory response was compared using a Chi‐square test. Results AGP‐positive leucocytes were found in 23% of cats. Compared with controls, the proportion of patients with positive granulocytes and monocytes was higher among sick cats (especially cats with diseases other than FIP) and cats with high serum AGP concentration, but not in cats with leucocytosis or that were FCoV‐seropositive. Conclusion AGP‐positive leucocytes can be found in feline blood, especially during inflammation. Conversely, no association between AGP‐positive leucocytes and FIP was found. Further studies are needed to elucidate the mechanism responsible for this finding and its diagnostic role in cats with inflammation.  相似文献   

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There are four outcomes to feline coronavirus (FCoV) infection: the development of feline infectious peritonitis (FIP, which is immune-mediated), subclinical infection, development of healthy lifelong carriers and a small minority of cats who resist infection (Addie and Jarrett, Veterinary Record 148 (2001) 649). Examination of the FCoV genome has shown that the same strain of virus can produce different clinical manifestations, suggesting that host genetic factors may also play a role in the outcome of infection. FIP is most prevalent amongst pedigree cats, although how much of this is due to them living in large groups (leading to higher virus challenge and stress which predisposes to FIP) and how much is due to genetic susceptibility is not known. If host genetics could be shown to play a role in disease, it may allow the detection of cats with a susceptibility to FIP and the development of increased population resistance through selective breeding. The feline leucocyte antigen (FLA) complex contains many genes that are central to the control of the immune response. In this preliminary study, we used clonal sequence analysis or reference strand conformational analysis (RSCA) to analyse the class II FLA-DRB of 25 cats for which the outcome of FCoV exposure was known. Individual cats were shown to have between two and six FLA-DRB alleles. There was no statistically significant association between the number of alleles and the outcome of FCoV infection. No particular allele appeared to be associated with either the development of FIP, resistance to FCoV, or the carrier status. However, the analysis was complicated by apparent breed variation in FLA-DRB and the small number of individuals in this study.  相似文献   

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Feline alpha(1)-acid glycoprotein (fAGP) increases during feline infectious peritonitis (FIP). We have recently identified a 29 kDa protein that we named feline AGP-related protein (fAGPrP) due to its cross-reactivity with an anti-human AGP monoclonal antibody. In this work we describe the tissue distribution of fAGPrP during FIP, and its relationship with feline coronavirus (FCoV) and myeloid cells. Tissues from five control cats and from 15 cats with FIP were examined by immunohistochemistry using monoclonal antibodies against human AGP, FCoV and myeloid antigens. Diffuse fAGPrP positivity within the lesions, likely due to vascular plasma leakage, endothelial and epithelial lining were detectable. Compared to controls, fAGPrP-expressing cells often increased in number and were diffusely distributed in lymph nodes, as usually occurs for IgM-producing plasma cells during early immune responses. These findings did not depend on the presence of FCoVs or of myeloid cells, suggesting that fAGPrP is not directly involved in the pathogenesis of FIP.  相似文献   

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OBJECTIVE: To determine whether expression of feline coronavirus (FCoV) 7b protein, as indicated by the presence of specific serum antibodies, consistently correlated with occurrence of feline infectious peritonitis (FIP) in cats. SAMPLE POPULATION: 95 serum samples submitted for various diagnostic assays and 20 samples from specific-pathogen-free cats tested as negative control samples. PROCEDURES: The 7b gene from a virulent strain of FCoV was cloned into a protein expression vector. The resultant recombinant protein was produced and used in antibody detection assays via western blot analysis of serum samples. Results were compared with those of an immunofluorescence assay (IFA) for FCoV-specific antibody and correlated with health status. RESULTS: Healthy IFA-seronegative cats were seronegative for antibodies against the 7b protein. Some healthy cats with detectable FCoV-specific antibodies as determined via IFA were seronegative for antibodies against the 7b protein. Serum from cats with FIP had antibodies against the 7b protein, including cats with negative results via conventional IFA. However, some healthy cats, as well as cats with conditions other than FIP that were seropositive to FCoV via IFA, were also seropositive for the 7b protein. CONCLUSIONS AND CLINICAL RELEVANCE: Expression of the 7b protein, as indicated by detection of antibodies against the protein, was found in most FCoV-infected cats. Seropositivity for this protein was not specific for the FCoV virulent biotype or a diagnosis of FIP.  相似文献   

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Feline infectious peritonitis (FIP) is a terminal disease of cats caused by systemic infection with a feline coronavirus (FCoV). FCoV biotypes that cause FIP are designated feline infectious peritonitis virus (FIPV), and are distinguished by their ability to infect macrophages and monocytes. Antigenically similar to their virulent counterparts are FCoV biotypes designated feline enteric coronavirus (FECV), which usually cause only mild enteritis and are unable to efficiently infect macrophages and monocytes. The FCoV spike protein mediates viral entry into the host cell and has previously been shown to determine the distinct tropism exhibited by certain isolates of FIPV and FECV, however, the molecular mechanism underlying viral pathogenesis has yet to be determined. Here we show that the FECV strain WSU 79-1683 (FECV-1683) is highly dependent on host cell cathepsin B and cathepsin L activity for entry into the host cell, as well as on the low pH of endocytic compartments. In addition, both cathepsin B and cathepsin L are able to induce a specific cleavage event in the FECV-1683 spike protein. In contrast, host cell entry by the FIPV strains WSU 79-1146 (FIPV-1146) and FIPV-DF2 proceeds independently of cathepsin L activity and low pH, but is still highly dependent on cathepsin B activity. In the case of FIPV-1146 and FIPV-DF2, infection of primary feline monocytes was also dependent on host cell cathepsin B activity, indicating that host cell cathepsins may play a role in the distinct tropisms displayed by different feline coronavirus biotypes.  相似文献   

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Feline coronavirus (FCoV) causes feline infectious peritonitis (FIP). Since 2002, when 20 cats on the Falkland Islands were found to be FCoV seronegative, only seronegative cats could be imported. Between 2005-2007, 95 pet and 10 feral cats tested negative by indirect immunofluorescence antibody (IFA) analysis using two strains of type II FCoV, two transmissible gastroenteritis virus assays, an enzyme-linked immunosorbent assay and rapid immunomigration test. Twenty-four samples (23%) showed non-specific fluorescence, mostly attributable to anti-nuclear antibodies (ANA). The reason for ANA was unclear: reactive samples were negative for Erhlichia canis antibodies; seven were feline immunodeficiency virus positive, but 15 were negative. It was not possible to determine retrospectively whether the cats had autoimmune disease, hyperthyroidism treatment, or recent vaccination which may also cause ANA. The FCoV/ FIP-free status of the Falkland Islands cats should be maintained by FCoV testing incoming cats. However, ANA can complicate interpretation of IFA tests.  相似文献   

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Feline coronaviruses (FCoV) vary widely in virulence causing a spectrum of clinical manifestations reaching from subclinical course to fatal feline infectious peritonitis (FIP). Independent of virulence variations they are separated into two different types, type I, the original FCoV, and type II, which is closely related to canine coronavirus (CCV). The prevalence of FCoV types in Austrian cat populations without FIP has been surveyed recently indicating that type I infections predominate. The distribution of FCoV types in cats, which had succumbed to FIP, however, was fairly unknown. PCR assays have been developed amplifying parts of the spike protein gene. Type-specific primer pairs were designed, generating PCR products of different sizes. A total of 94 organ pools of cats with histopathologically verified FIP was tested. A clear differentiation was achieved in 74 cats, 86% of them were type I positive, 7% type II positive, and 7% were positive for both types. These findings demonstrate that in FIP cases FCoV type I predominates, too, nonetheless, in 14% of the cases FCoV type II was detected, suggesting its causative involvement in cases of FIP.  相似文献   

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The possible role of some acute phase proteins (APPs) and immunoglobulins in both the pathogenesis and diagnosis of feline infectious peritonitis (FIP) has been investigated. Serum protein electrophoresis and the concentration of haptoglobin (Hp), serum amyloid A (SAA), alpha(1)-acid glycoprotein (AGP), IgG and IgM were evaluated in cats exposed to feline coronavirus (FCoV) and in cats with FIP. The highest concentration of APPs was detected in affected cats, confirming the role of these proteins in supporting a clinical diagnosis of FIP. Repeated samplings from both FIP affected and FCoV-exposed cats showed that when FIP appeared in the group, all the cats had increased APP levels. This increase persisted only in cats that developed FIP (in spite of a decrease in alpha(2)-globulins) but it was only transient in FCoV-exposed cats, in which a long lasting increase in alpha(2)-globulins was observed. These results suggest that changes in the electrophoretic motility of APPs or APPs other than Hp, SAA and AGP might be involved in the pathogenesis of FIP or in protecting cats from the disease.  相似文献   

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