Tissue distribution of virus replication in cats experimentally infected with distinct feline calicivirus isolates.

Four specific pathogen-free (SPF) cats were each inoculated with one of two genetically and antigenically well characterized feline caliciviruses originally isolated from cats with acute respiratory disease (FCV-KS100/2), or with chronic stomatitis (FCV-KS20). Two cats of each group were euthanized at day 10 post infection and two cats at day 28. No clear differences between the clinical disease induced by the two isolates could be observed, and no apparent differences in the tissue spectrum were seen between day 10 and 28. No persistent virus shedding was observed over the 4-week period of this experiment.     

Molecular virology of feline calicivirus.

Caliciviridae are small, nonenveloped, positive-stranded RNA viruses. Much of our understanding of the molecular biology of the caliciviruses has come from the study of the naturally occurring animal caliciviruses. In particular, many studies have focused on the molecular virology of feline calicivirus (FCV), which reflects its importance as a natural pathogen of cats. FCVs demonstrate a remarkable capacity for high genetic, antigenic, and clinical diversity; "outbreak" vaccine resistant strains occur frequently. This article updates the reader on the current status of clinical behavior and pathogenesis of FCV.     

Detection of protective antibody titers against feline panleukopenia virus, feline herpesvirus-1, and feline calicivirus in shelter cats using a point-of-care ELISA

Serum antibody titers are a useful measurement of protection against infection (feline panleukopenia virus [FPV]) or clinical disease (feline herpesvirus-1 [FHV] and feline calicivirus [FCV]), and their determination has been recommended as part of disease outbreak management in animal shelters. The objective of this study was to determine the sensitivity, specificity, and inter-observer and inter-assay agreement of two semi-quantitative point-of-care assays for the detection of protective antibody titers (PAT) against FPV, FHV and FCV in shelter cats. Low sensitivity for FPV antibodies (28%) rendered a canine point-of-care assay inappropriate for use in cats. The feline point-of-care assay also had low sensitivity (49%) and low negative predictive value (74%) for FPV PAT detection, but was highly accurate in the assessment of FHV and FCV PAT. Improvements in accuracy and repeatability of FPV PAT determination could make this tool a valuable component of a disease outbreak response in animal shelters.     

猫杯状病毒不同分离株致病性的比较

为确定猫杯状病毒(Feline calicivirus,FCV)SH、JL-1、JL-2分离株毒力强弱,将其分别人工接种6~11周龄健康非免疫家猫,分成接种组和对照组。接种前后分别测定各组猫体温、体质量,观察发病情况及临床症状,按照欧洲药典对症状进行计分。于感染后14d麻醉处死,制备病料组织切片,观察组织器官的病理变化。结果显示,家猫感染FCV后总发病率为100%,死亡率为66.7%;SH、JL-1、JL-2组临床症状平均得分分别为8、4、9,对照组得分为1。病理解剖观察发现,猫感染FCV后,以鼻、眼分泌物增加,口腔溃疡为特征,消化道病变较轻微,肺部出现不同程度的变性、出血,呈明显病理性肉样变;病理组织学观察发现,肺脏有数量不等的肺泡上皮细胞和巨噬细胞脱落,伴随少量纤维蛋白渗出和弥漫性肺泡损伤。结果表明,FCV SH、JL-1、JL-2分离株均有一定的致病性,其中以JL-2株的毒力最强。     

Isolation of feline calicivirus and feline herpesvirus from domestic cats 1980 to 1989

Isolation rates of feline herpesvirus (FHV) and feline calicivirus (FCV) from oropharyngeal swabs, taken from 6866 cats in 1980 to 1989 were studied retrospectively. FCV was isolated from 1364 (19.9 per cent) and FHV from 285 (4.2 per cent). The ratio of FCV:FHV isolations varied from 1.3:1 to 15:1 in individual years with an overall ratio of 4.8:1. Isolation of both viruses was fairly uniform for each year and there was no breed or sex disposition to either virus. Of 872 cats shedding FCV and 213 cats shedding FHV, of known age, 447 (51.3 per cent) with FCV and 140 (65.7 per cent) with FHV were under one year old, compared to only 35.3 per cent of the whole population sampled. For the years 1985 to 1989, more information was obtained about the cases. Of 4626 cats tested, 1180 (25.5 per cent) had acute upper respiratory tract disease (URTD) of which 348 (29.5 per cent) were shedding FCV and 162 (13.7 per cent) FHV. A further 597 had chronic URTD and of these, 102 (17.1 per cent) were shedding FCV and 18 (3 per cent) FHV. In 120 cases of suspected vaccine reaction/breakdown, FCV was isolated from 34 (28.3 per cent) and FHV from only two (1.7 per cent). FHV was not isolated from any of 412 cases presenting with chronic gingivitis/stomatitis alone; 181 (43.9 per cent) were shedding FCV and when cats with other signs in addition to chronic gingivitis were included, this proportion increased to 70.4 per cent.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isolation of feline herpesvirus-1 and feline calicivirus from healthy cats in Swedish breeding catteries

Feline calicivirus (FCV) could be isolated from four cats (2.6%) and feline herpesvirus-1 (FHV) from none of 152 clinically healthy cats from 22 Swedish breeding catteries. These cats had all previously shown signs of respiratory tract disease or conjunctivitis, although several years ago. The results suggest that carriers of FCV and FHV were uncommon in Swedish breeding catteries studied. Prevalence rates in other European countries and North America are usually higher, especially of FCV. The lower prevalence rates in our study might be explained by test group selection, differences in factors such as management, environment, or genetic constitution of the cats, or by sample handling. It was concluded that the presence of an FCV shedder in the cattery does not mean that all cats in the group are infected, but special measures are recommended to avoid infection of susceptible cats.     

猎豹与虎猫杯状病毒的分离及其超变区基因比较研究

用F81细胞从上海某动物园患口腔溃疡的猎豹和虎的唾液病料中分离获得两株杯状病毒，经形态学、理化学、生物学鉴定和病毒核酸超变区基因RT-PCR扩增与序列测定证明两株病毒均为猫杯状病毒(FCV)，分别命名为FCV/cheetah/Shanghai/02/2002与FCV／tiger/Shanghai／03/2002。人工感染猫可引起体温升高，口腔溃疡，食欲下降等症状。两株病毒的超变区序列520bp长片段问的同源性为99.2％，与国内桂林虎分离株(TFCV9710)的同源性为74．0％，与国外分离株的总体同源性为58．1％，说明不同宿主或同种不同个体间杯状病毒分离株超变区核酸差异十分显著，符合猫杯状病毒的分子生物学特征。     

Studies on the role of feline calicivirus in chronic stomatitis in cats.

Two groups of cats were inoculated oro-nasally with one of two isolates of feline calicivirus (FCV) from clinical cases of chronic stomatitis. All cats developed signs typical of acute FCV infection; namely, ocular and nasal discharge, conjunctivitis, and marked oral ulceration. None of the cats shed virus beyond 28 days. Seronegative control cats were then infected with a lower dose of one isolate, but again only acute signs were seen and no carriers produced. The original cats were then re-infected with the heterologous isolate. As before, only signs of acute disease were seen, but the range of clinical signs and severity was reduced. Virus shedding patterns in one group were similar to those seen originally, but in the other the duration was reduced. No chronic stomatitis developed over the 10 months of the study. Serum virus neutralising and serum and salivary class specific immunoglobulin responses were investigated. Although long-term carriers were not induced, no relationship between cessation of virus shedding in an individual animal and systemic and local antibody responses was seen.     

Lethal outbreak of disease associated with feline calicivirus infection in cats

Recently, in the USA, virulent mutants of feline calicivirus (FCV) have been identified as the cause of a severe and acute virulent systemic disease, characterised by jaundice, oedema and high mortality in groups of cats. This severe manifestation of FCV disease has so far only been reported in the USA. However, in 2003, an outbreak of disease affected a household of four adult cats and an adult cat from a neighbouring household in the UK. Three of the adult cats in the household and the neighbouring cat developed clinical signs including pyrexia (39.5 to 40.5 degrees C), lameness, voice loss, inappetence and jaundice. One cat was euthanased in extremis, two died and one recovered. A postmortem examination of one of the cats revealed focal cellulitis around the right hock and right elbow joints. The principal finding of histopathological examinations of selected organs from two of the cats was disseminated hepatocellular necrosis with mild inflammatory infiltration. Immunohistology identified FCV antigen in parenchymal and Kupffer cells in the liver of both animals and in alveolar macrophages of one of them. In addition, calicivirus-like particles were observed by electron microscopy within the hepatocytes of one cat. FCV was isolated from two of the dead cats and from the two surviving cats. Sequence analysis showed that they were all infected with the same strain of virus, but that it was different from strains of FCV associated with the virulent systemic disease in cats in the USA. The outbreak was successfully controlled by quarantine in the owner's house.     

Detection of feline calicivirus antigens in the joints of infected cats

Twelve specific pathogen free cats were used to investigate the role of calicivirus in causing lameness. These were divided into two groups each of six cats; one group of cats had previously been vaccinated, the other had not. Three cats in each group were given live vaccine virus (F9 related) by the subcutaneous route and two in each group were challenged intranasally with field virus (A4), either four or seven days before euthanasia. The other two cats were controls. Virus was isolated from the oropharynx of five cats and the conjunctiva of a single cat. Four of these cats had been given the field virus and two the vaccine strain; the latter two cats had been previously immunised and had high circulating neutralising antibodies to calicivirus. No virus was isolated from the joints of any cat but immunofluorescence examination revealed viral antigens within the synovial macrophages of 14 joints from five cats, three having been given the field virus and two the vaccine virus seven days before euthanasia. Immunofluorescence also demonstrated the presence of immunoglobulin and complement within synovial macrophages suggesting that the virus was in the form of an immune complex. No lameness was reported in any cat and the synovial histological changes were minimal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Natural cases of polyarthritis associated with feline calicivirus infection in cats

Veterinary Research Communications - The limping syndrome is occasionally reported during acute feline calicivirus (FCV) infections or as consequence of vaccination. In this retrospective study,...     

Sequence variation within the capsid protein of Australian isolates of feline calicivirus.

The capsid protein of Australian feline calicivirus (FCV) isolates is demonstrably different from the prototype strain F9. Five Australian isolates of FCV, dating from 1970 to 1989, were analysed by western blotting and immunoprecipitation. Varying reactivity to a panel of F9 specific monoclonal antibodies (MAbs) was observed. DNA sequencing of RT-PCR generated clones supported the observation of variation between capsid proteins. Predicted amino acid sequences varied by 11 to 17.5% across the whole capsid when compared to the published F9 sequence. Differences in amino acid sequence were most apparent in previously described hypervariable regions (C and E). Within hypervariable region E differences of 22 to 34% were observed compared to F9. The observed lack of reactivity to F9 MAbs correlated with amino acid changes within previously characterized binding sites within region E.     

Two outbreaks of virulent systemic feline calicivirus infection in cats in Germany

Over the last years, several outbreaks of virulent systemic feline calicivirus (VS-FCV) infection have been described in the USA and several European countries. The paper describes two outbreaks of VS-FCV infection in cats in Germany. Data concerning clinical, laboratory, and histopathological features ofVS-FCV infection were collected from two outbreaks affecting 55 and 4 cats, respectively. Presence of feline calicivirus was confirmed by PCR followed by sequencing of the PCR-products. Clinical signs were variable, including severe upper respiratory tract infection, dyspnoea, oral and footpad ulceration, facial oedema, enteritis, pneumonia, bleeding disorder, high fever, and icterus. Both outbreaks were characterized by a high mortality rate.The present report describes the first documented outbreaks of VS-FCV infection in cats in Germany. Clinical and histopathological features are comparable to outbreaks described in the USA and Europe. However, phylogenetic analysis of the virus genome suggests that virus strains involved in these outbreaks were different from each other and from virulent strains isolated before, confirming the known genetic variability of FCV.     

Molecular subtyping of feline immunodeficiency virus from cats in Melbourne

OBJECTIVE: To determine the subtypes of feline immunodeficiency virus (FIV) present in the domestic cat population in Melbourne. METHODS: Blood samples were collected from 42 cats that had serum antibodies against FIV. DNA was extracted and subjected to polymerase chain reaction (PCR) to amplify variable regions of the envelope (env) and group specific antigen (gag) genes of FIV. PCR products were directly sequenced or sequenced after cloning when direct sequencing yielded ambiguous results. Phylogenetic analysis was performed and comparisons made with representative sequences of different subtypes. RESULTS: The variable region of the env gene was successfully amplified by PCR from 41 of the 42 cats. All 41 were found to cluster with subtype A env sequences. The variable region of the gag gene was successfully amplified by PCR from all 42 cats. Forty-one were found to cluster with subtype A gag genes and one was found to cluster with subtype B sequences, suggesting that it may be derived from a recombinant env A/gag B virus. CONCLUSIONS: Subtype A is the predominant FIV type in Melbourne, although a subtype A/B recombinant was identified in the population of FIV positive cats. These results of env gene analysis were similar to those in a previous Australian study, suggesting that subtype A predominates in Australia. The results of the gag gene analysis show the importance of analysing multiple areas of the FIV genome when assigning FIV subtypes. Comparison with other major urban centres may provide useful information about the phylogenic diversity of FIV in Australia.     

The preparation of a polyvalent feline calicivirus antiserum.

A polyvalent antiserum capable of neutralizing 82 isolates of feline calicivirus made from cats in various parts of North America was produced by the sequential inoculation of SPF cats at three-week intervals with feline calicivirus strains F-9, 68-2024 and FS, followed by a final booster inoculation two weeks after the third inoculation with all three strains combined. Sera raised against the same strains but individually and then pooled failed to show such broad cross-neutralizing capacity. The polyvalent serum should prove useful for the confirmation of an isolation of feline calicivirus.     

Long-term analysis of feline calicivirus prevalence and viral shedding patterns in naturally infected colonies of domestic cats

Feline calicivirus (FCV) is a highly infectious respiratory pathogen of domestic cats. The prevalence of FCV in the general cat population is high, particularly in multi-cat households, largely because many clinically recovered cats remain persistently infected carriers. In order to assess how FCV circulates in such groups and to assess the contribution that each individual animal makes to the epidemiology of the disease, we have carried out the first detailed analysis of long-term shedding patterns of FCV in individual cats within naturally infected colonies. The prevalence of FCV in each of the groups on individual sampling occasions ranged from 0% to 91%, with averages for the individual colonies ranging from 6% to 75%. Within each of the colonies, one to three distinct strains of FCV were identified. Individual cats showed a spectrum of FCV shedding patterns over the sampling period which broadly grouped into three categories: those that shed virus relatively consistently, those that shed virus intermittently, and those that appeared never to shed virus. This is the first report identifying non-shedder cats that appear resistant to FCV infection over long periods of time, despite being continually exposed to virus. Such resistance appeared to be age related, which may have been immune-mediated, although by analogy with other caliciviruses, factors such as host genetic resistance may play a role. Given that a proportion of the population appears to be resistant to infection, clearly the cohort of cats that consistently shed virus are likely to provide an important mechanism whereby infection can be maintained in small populations.