猫病毒性鼻气管炎的诊断与防治

猫病毒性鼻气管炎病毒,又名猫疱疹病毒1型（Feline Herpesvirus type1,FHV-1）,属于疱疹病毒科中的α-疱疹病毒,可引起猫及其他猫科动物的眼病及呼吸道疾病,发病率可达100％,成年猫死亡率很低,但幼猫的死亡率可达50％。本病在世界范围内广泛流行,我国己多次发现临床可疑病例。猫感染FHV-1后,虽然有抗体产生,但病毒可潜伏到三叉神经节,     

A survey of feline viral rhinotracheitis and feline picornavirus infection in Britain

A survey of healthy and respiratory-diseased cats, post-mortem kitten specimens and serum samples, showed the widespread occurrence of feline rhinotracheitis virus infection (FVR) and feline picornavirus infection (FPI) in Britain. Both virus groups were on occasions isolated from clinically healthy cats but they were more frequently associated with upper respiratory disease. No colony outbreak of respiratory disease was investigated without either FVR or FPI being incriminated. Clinical differentiation of FVR and FPI was imposible with certainty although FVR infection was typically more severe. Pathologically, FVR could be distinguished particularly in the early stages by the presence of specific intranuclear inclusions in mucosal and submucosal gland cells of the respiratory tract and by a generally more severe mucosal destruction. FPI was typified by a mild disorganization of mucosae and mononuclear cell infiltrations. Serological investigations demonstrated that, in colonies particularly, high titres of antibody against both FVR virus and a spectrum of feline picornaviruses were attained in adult cats, a reflection of the endemic nature of these viruses. Bacteria played a secondary role in both FVR and FPI, and there was no evidence for chlamydial agents being important in the aetiology of feline respiratory disease in Britain. Résumé. Une étude de chats sains et atteints de maladies des voies respiratoires, de spécimens d'autopsie de chatons et d‘échantillons de sérum montre que les rhinotrachéites félines avec infection d'origine virale (RFV) et les infections ftlines de “picornavirus” (IFP) sont très répandues en Grande-Bretagne. A différentes occasions, les deux groupes de virus, provenant de chats sains du point de vue clinique, ont été isolés mais ces virus étaient le plus souvent lies aux maladies respiratoires d'origine otorhinolaryngologique. Toutes les recherches sur les maladies respiratoires se declarant par colonies indiquaient la présence soit de RFV ou de I'IFP. La dif-férenciation clinique certaine de RFV et d'IFP fut impossible bien que l'infection RFV fût plus grave come prévu. Pathologiquement, il fut possible de distinguer le RFV, surtout dans les premiers stades, par la présence d'inclusions intranucléaires spécifiques dans les cellules des glandes muqueuses et submuqueuses des voies respiratoires et par une destruction muqueuse généralement plus grave. L'IFP était caracterisée par une légère désorganisation des membranes muqueuses et des infiltrations de cellules mononucléaires. Des recherches sérologiques ont montré, surtout pour les colonies, qu'on rencontre des titres élevés d'anticorps contre le virus RFV ainsi qu'un spectre de “piconavirus” felins chez des chats adultes, ce qui réflète la nature endémique de ces virus. Les bactéries n'ont joué qu'un rôle secondaire, à la fois dans les RFV et les IFP et il n'y eut pas d'indices indiquant l'importance des agents “Chlamydiaux” dans l‘étiologie des maladies respiratoires félines en Grande-Bretagne. Zusammenfassung. Ein zusammenfassender Bericht über geusunde Katzen und solche mit Erkrankungen der Atmungsorgane, Sektionsproben junger Katzen und Serumproben zeigte das verbreitete Auftreten der Rhinotracheitis-Virus infektion der Katzen (FVR) und der Picornavirusinfektion der Katzen (FPI) in Grossbritannien. Beide Virusgmppen wurden gelegentlich aus klinisch gesunden Katzen isoliert, waren aber häufiger mit Erkrankungen der oberen Atemwege verbunden. Es wurde kein massiertes Auftreten von Erkrankungen der Atmungswege untersucht, ohne dass entweder FVR oder FPI als Ursache anzusehen waren. Die klinische Differenzierung von FVR und FPI war nicht mit Sicherheit möglich, obwohl die FVR-Infektion typisch schwerer war. Pathologisch konnte FVR besonders in den Frühstadien durch die Anwesenheit spezifischer intranuklearer Einschlüsse in mucösen und submucösen Drüsenzellen des Respirationstraktes und durch eine allgemein schwerere Schleimhautzer-störung unterschieden werden. FPI war durch eine schwache Disorganisation mucöser und mononuklearer Zellinfiltrationen charakterisiert. Serologische Untersuchungen zeigten, dass besonders in Kolonien hohe Antikörperkonzentrationen gegen FVR-Virus und ein Spektrum von Picornaviren der Katze bei erwachsenen Katzen erreicht wurden, was auf den endemischen Charakter dieser Viren hinweist. Bakterien spielten bei FVR und FPI eine sekundäre Rolle, und es liess kein Anzeichen darauf schliessen, dass chlamydiale Agentien für die Ätiologie der Erkrankungen der Atmungsorgane von Katzen in Grossbritannien eine Rolle spielten.     

Diagnosis of feline haemoplasma infection using a real-time PCR assay

Haemobartonella felis has been reclassified within the genus Mycoplasma as Mycoplasma haemofelis and 'Candidatus Mycoplasma haemominutum', collectively referred to as the feline haemoplasmas. A total of 78 cats from the Johannesburg area that had blood samples submitted to a private veterinary laboratory were tested using a real-time polymerase chain reaction (PCR) assay able to detect and distinguish the two feline haemoplasma (basonym Haemobartonella) species. All samples had been diagnosed with haemoplasma infection by cytological examination of blood smears. Statistical analysis was performed to evaluate associations between haemoplasma status, age, and haematological and biochemical parameters. On PCR assay 43 cats (55%) were haemoplasma negative, 25 (32.1%) positive for 'Candidatus Mycoplasma haemominutum', 5 (6.4%) positive for Mycoplasma haemofelis and 5 (6.4%) positive for both species. Significant inverse correlation was found between the amount of M. haemofelis DNA present in the blood and the haematocrit value. Cats that were positive for M. haemofelis showed macrocytic regenerative anaemia, monocytosis and thrombocytopaenia. This report documents the existence of both haemoplasma species in cats in South Africa.     

Vaccination against feline viral rhinotracheitis in kittens with maternally derived feline viral rhinotracheitis antibodies

The efficacy of a modified live-virus intranasal vaccine and a killed-virus adjuvanted parenteral vaccine in inducing protective immunity against feline viral rhinotracheitis (FVR) was evaluated in kittens with and without maternally derived FVR antibodies. The intranasal vaccine was given as a single dose to kittens 5 weeks old, and the parenteral vaccine was administered in 2 doses at 5 and 7 weeks of age. Seroconversion was delayed for 5 to 10 days in kittens with maternally derived antibodies, but occurred in all vaccinated kittens by 8 weeks of age. When virulent FVR virus was given, both vaccines provided satisfactory protection against disease but did not prevent infection. The results indicated that the modified live-virus intranasal vaccine or the killed-virus adjuvanted parenteral vaccine can be used successfully in kittens with residual maternally derived FVR antibodies.     

Diagnosis of feline leukaemia virus infection by semi-quantitative real-time polymerase chain reaction

In this paper the design and use of a semi-quantitative real-time polymerase chain reaction assay (RT-PCR) for feline leukaemia virus (FeLV) provirus is described. Its performance is evaluated against established methods of FeLV diagnosis, including virus isolation and enzyme-linked immunoassay (ELISA) in a population of naturally infected cats. The RT-PCR assay is found to have both a high sensitivity (0.92) and specificity (0.99) when examined by expectation maximisation methods and is also able to detect a large number of cats with low FeLV proviral loads that were negative by other conventional test methods.     

Virulent systemic feline calicivirus infection: local cytokine modulation and contribution of viral mutants

Virulent systemic feline calicivirus (VS-FCV) is a novel, emerging pathogen with mortality up to 67% even in previously healthy adult cats; VS-FCV has resulted in at least six epidemics since 1998. Affected cats have systemic vascular compromise and hemorrhagic-fever like signs in part due to viral invasion of epithelium and endothelium, coupled with host cytokine responses. Affected skin tissues had, on average, 3.8 elevated cytokines compared with control tissue, with prominent upregulation in IL-10, TNF-alpha, and MIP-1alpha. Sequencing of most of the genomes of two VS-FCV strains documented patterns of virus relatedness and implicated changes in the capsid gene in the emerging phenotype, possibly through initiation of immune mechanisms manifest in the cytokine changes. Understanding the features contributing to the emergence of this disease is critical for management and prevention of this and similar outbreaks attributable to RNA viruses in animals and humans.     

Diagnosis of bovine viral diarrhea virus infection using monoclonal antibodies

The monoclonal antibody (MAb) D89 against bovine viral diarrhea virus (BVDV) was used in conjunction with fluorescein-conjugated anti-mouse immunoglobulin in an indirect fluorescent antibody (IFA) procedure on frozen tissue sections and cell culture. During the 2-year study, BVDV was isolated from specimens submitted in 460 cases. The D89 Mab detected all but 2 BVDV isolates, both cytopathic. In 316 of the cases in which BVD virus was detected by IFA, specimens were inoculated on bovine turbinate cells and examined for BVDV antigens at 3-5, 10, and 20 days postinoculation. The BVDV was detected in 238/316 cases (75%) after 3-5 days incubation. The remainder were not detected until 10 or 20 days postinoculation. Virus isolation was enhanced in the early test if plates were centrifuged at the time of inoculation. Results suggest that D89 monoclonal antibody is a suitable diagnostic reagent for the detection of BVDV isolated from diagnostic specimens. The D89 MAb can be used for the detection of BVDV in both cell culture and tissues. Combination of D89 with another BVDV MAb (C17) did not improve the ability to detect BVDV in tissues compared to using D89 only, and the combined Mab's resulted in an increase in nonspecific fluorescence when used on tissues. Although pooling of different BVDV monoclonal antibodies may be necessary to detect all strains of BVDV in cell culture, pooling should be used with caution on tissues. Early detection of BVDV in cell culture by this IFA procedure permits faster confirmation of BVDV diagnosis when compared to the usual routine testing for noncytopathic BVDV at termination of first passage in cell culture.     

Diagnosis of feline haemoplasma infection in Australian cats using a real-time PCR assay

A total of 147 cats from the Sydney area of Australia that had blood samples submitted to veterinary laboratories were tested using a real-time polymerase chain reaction (PCR) assay able to detect and distinguish the two feline haemoplasma species. This sample number included two cats diagnosed with feline haemoplasma infection by routine blood smear examination. Statistical analysis was performed to evaluate associations between haemoplasma infection, age, sex, breed, haematocrit (HCT) values and anaemia status. One hundred and six cats (72.1%) were negative. Thirty-four cats (23.1%) were positive for 'Candidatus M. haemominutum', six cats (4.1%) were positive for M. haemofelis and one cat (0.7%) was positive for both species. Older, male, non-pedigree cats, with lower HCT values were more likely to be infected with 'Candidatus M. haemominutum'. Significant inverse correlation was found between the amount of M. haemofelis DNA present in the blood and the HCT value. This report documents the existence of, and prevalence of, both haemoplasma species in a sample of cats in Australia and is the first to use quantitative real-time PCR in a prevalence study for haemoplasma infection.     

Carrier-state infection of feline T-lymphoblastoid cells with feline calicivirus

The susceptibility of feline T lymphocytes to feline calicivirus (FCV) in vitro was investigated using feline T-lymphoblastoid cell lines, namely MYA-1 and FL74 cells. The virus titers of supernatants in FCV-infected MYA-1 and FL74 cell cultures increased rapidly, and FCV antigens were also detected in the FCV-infected cells. There were slight differences in the molecular weights of capsid proteins expressed in FCV-infected MYA-1, FL74 and Crandell feline kidney cells. MYA-1 and FL74 cells were productively and persistently infected with FCV, and FCV antigens were observed in the FCV-infected cells for more than one month. At 3 months post infection, FCV-infected FL74 cells that stopped producing infectious FCV could be reinfected with FCV. However, no cytopathic effects were observed.     

Diagnosis of feline leukemia virus and feline immunodeficiency virus infections

Feline leukemia virus is an oncogenic retrovirus that can result in a wide variety of neoplastic and non-neoplastic diseases, including immunosuppression. Diagnosis of FeLV infection can be achieved by several methods, including virus isolation; IFA assay of a peripheral blood smear; and detection of a viral protein (called p27) by ELISA testing of whole blood, plasma, serum, saliva, or tears. Commercially available ELISA kits have revolutionized FeLV testing and have become very popular as "in-house" procedures. This article discusses the interpretation of ELISA results and compares them with IFA assay findings. Feline immunodeficiency virus is a lentivirus that causes immunosuppression, but not neoplasia, in cats. It originally was called feline T-lymphotropic lentivirus. Differentiating FIV infection from the immunosuppressive type of FeLV infection requires virus isolation or serology. The most rapid method for diagnosis of FIV infection is ELISA testing for antiviral antibody.     

Experimentally induced feline chlamydial infection (feline pneumonitis)

Cats exposed to aerosols of feline Chlamydia psittaci developed a disease characterized principally by conjunctivitis. Signs of conjunctivitis appeared between postexposure days (PED) 5 and 10, were often unilateral initially, and persisted for 22 to 45 days. Fever followed the onset of conjunctivitis (PED 11 to 15) and persisted for 3 to 8 days. Signs of mild rhinitis (occasional sneezing and mild serous nasal discharge) occurred in some cats between PED 8 and 37. Neither signs of lower respiratory tract disease nor significant pulmonary lesions were produced by the feline pneumonitis agent. Small foci of pneumonia were detected microscopically in 3 of 6 cats examined between PED 7 and 14. Chlamydiae were identified between PED 7 and 14 in the cytoplasm of epithelial cells in stained conjunctival smears. Conjunctivitis persisted for at least 18 days after chlamydiae no longer were detectable in conjunctival smears. Low levels of chlamydial infectivity, however, still were present in conjunctiva and lung on PED 45.     

Clinical aspects of feline immunodeficiency and feline leukemia virus infection

Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are retroviruses with a global impact on the health of domestic cats. The two viruses differ in their potential to cause disease. FIV can cause an acquired immunodeficiency syndrome that increases the risk of developing opportunistic infections, neurological diseases, and tumors. In most naturally infected cats, however, FIV itself does not cause severe clinical signs, and FIV-infected cats may live many years without any health problems. FeLV is more pathogenic, and was long considered to be responsible for more clinical syndromes than any other agent in cats. FeLV can cause tumors (mainly lymphoma), bone marrow suppression syndromes (mainly anemia) and lead to secondary infectious diseases caused by suppressive effects of the virus on bone marrow and the immune system. Today, FeLV is less important as a deadly infectious agent as in the last 20 years prevalence has been decreasing in most countries.     

Pathogenesis of feline enteric coronavirus infection

Fifty-one specific pathogen-free (SPF) cats 10 weeks to 13 years of age were infected with a cat-to-cat fecal-oral passed strain of feline enteric coronavirus (FECV). Clinical signs ranged from unapparent to a mild and self-limiting diarrhea. Twenty-nine of these cats were FECV na?ve before infection and followed sequentially for fecal virus shedding and antibody responses over a period of 8-48 months. Fecal shedding, as determined by real-time polymerase chain reaction (RT-PCR) from rectal swabs, appeared within a week and was significantly higher in kittens than older cats. FECV shedding remained at high levels for 2-10 months before eventually evolving into one of three excretion patterns. Eleven cats shed the virus persistently at varying levels over an observation period of 9-24 months. Eleven cats appeared to have periods of virus shedding interlaced with periods of non-shedding (intermittent or recurrent shedders), and seven cats ceased shedding after 5-19 months (average 12 months). There was no change in the patterns of virus shedding among cats that were excreting FECV at the time of a secondary challenge exposure. Four cats, which had ceased shedding, re-manifested a primary type infection when secondarily infected. Cats with higher feline coronavirus (FCoV) antibody titers were significantly more likely to shed virus, while cats with lower titers were significantly less likely to be shedding. Twenty-two kittens born to experimentally infected project queens began shedding virus spontaneously, but never before 9-10 weeks of age. Natural kittenhood infections appeared to be low grade and abortive. However, a characteristic primary type infection occurred following experimental infection with FECV at 12-15 weeks of age. Pregnancy, parturition and lactation had no influence on fecal shedding by queens. Methylprednisolone acetate treatment did not induce non-shedders to shed and shedders to increase shedding.     

Pathogenesis of feline gastric chlamydial infection

Studies were conducted to determine whether the gastric chlamydiae that have been observed recently in cats are of pathologic significance. Chlamydiae were isolated in mouse L cell cultures from the homogenized pooled gastric mucosa of 3 cats that had been identified, by histopathologic examination, to have gastric chlamydiosis. Ten specific-pathogen-free kittens were exposed by aerosol and oral inoculation to the harvested feline gastric chlamydiae cell-culture media. In general, the clinical signs and lesions were conjunctivitis, rhinitis, and mild gastritis. The clinical signs and lesions were most severe in 2 chlamydia-infected kittens that had received methylprednisolone acetate (50 mg/kg of body weight). Chlamydiae were demonstrated in epithelial cells of conjunctival and nasal smears in 10 of 10 infected kittens from postexposure days 7 through 35. In addition, chlamydiae were isolated in L cell cultures from a variety of antemortem and postmortem specimens from infected kittens. The present study provided evidence that feline gastric chlamydiae, under appropriate conditions, were capable of inducing, in cats, clinical signs and lesions similar to those induced by the feline pneumonitis agent.     

Strain-specific viral distribution and neuropathology of feline immunodeficiency virus

Feline immunodeficiency virus (FIV) is a naturally occurring lentivirus of domestic cats, and is the causative agent of feline AIDS. Similar to human immunodeficiency virus (HIV), the pathogenesis of FIV involves infection of lymphocytes and macrophages, and results in chronic progressive immune system collapse and death. Neuropathologic correlates of FIV infection have not yet been elucidated, and may be relevant to understanding HIV-associated neurologic disease (neuroAIDS). As in HIV, FIV strains have been shown to express differential tendencies towards development of clinical neuroAIDS. To interrogate viral genetic determinants that might contribute to neuropathogenicity, cats were exposed to two well-characterized FIV strains with divergent clinical phenotypes and a chimeric strain as follows: FIV(PPR) (PPR, relatively apathogenic but associated with neurologic manifestations), FIV(C36) (C36, immunopathogenic but without associated neurologic disease), and Pcenv (a chimeric virus consisting of a PPR backbone with substituted C36 env region). A sham inoculum control group was also included. Peripheral nerve conduction velocity, CNS imaging studies, viral loads and hematologic analysis were performed over a 12 month period. At termination of the study (350 days post-inoculation), brain sections were obtained from four anatomic locations known to be involved in human and primate lentiviral neuroAIDS. Histological and immunohistochemical evaluation with seven markers of inflammation revealed that Pcenv infection resulted in mild inflammation of the CNS, microglial activation, neuronal degeneration and apoptosis, while C36 and PPR strains induced minimal neuropathologic changes. Conduction velocity aberrations were noted peripherally in all three groups at 63 weeks post-infection. Pcenv viral load in this study was intermediate to the parental strains (C36 demonstrating the highest viral load and PPR the lowest). These results collectively suggest that (i) 3' C36 genomic elements contribute to viral replication characteristics, and (ii) 5' PPR genomic elements contribute to CNS manifestations. This study illustrates the potential for FIV to provide valuable information about neuroAIDS pathogenesis related to genotype and viral kinetics, as well as to identify strains useful to evaluation of therapeutic intervention.     

A survey of feline viral upper respiratory tract infections

A survey of viruses associated with feline respiratory disease was conducted by culturing from 100 swabs collected from cats with respiratory disease and 50 swabs collected from a group of apparently healthy cats. In the first group, 27 herpesviruses and 24 caliciviruses were isolated from 50 cats, whereas 1 herpesvirus and 2caliciviruses were isolated from the second group. Caliciviruses were more commonly isolated from animals under 1 year old and appeared to be more closely associated than herpesviruses with buccal ulceration.