Prevalence and risk factors for common respiratory pathogens within a cohort of pet cats in the UK.

OBJECTIVES: Feline herpesvirus (FHV), feline calicivirus (FCV) and Chlamydia felis are common causes of upper respiratory tract disease (URTD) in cats. Their prevalence in the UK pet cat population has not been reported and little is known regarding the risk factors for their oral carriage. METHODS: Total nucleic acid was extracted from owner-collected buccal swabs (n=600) from cats enrolled in a self-selected longitudinal cohort study. Duplex quantitative PCRs for the detection of FHV and C. felis genomic DNA and reverse-transcriptase quantitative PCRs for the detection of FCV genomic RNA were performed. Duplicates, swabs with insufficient host DNA/RNA, and cats with missing data were excluded. Selected epidemiological data were interrogated using univariable and multi-variable logistic regression modelling to identify risk factors. RESULTS: Data from 430 cats were included in the final statistical model. Of these, 2.1% (n=9/430; 95% CI 1.0% to 3.9%) were positive for FHV, 13.3% (n=57/430; 95% CI 10.2% to 16.8%) positive for FCV and 1.2% (n=5/430; 95% CI 0.4% to 2.7%) positive for C. felis. FCV co-infection was present in five (44%) FHV-positive cats and three (60%) C. felis-positive cats. FCV carriage was more frequent in purebred cats (odds ratio 2.48; 95% CI 1.37 to 4.49) and in cats with current or historical clinical signs compatible with URTD (odds ratio 2.98; 95% CI 1.22 to 7.27). CLINICAL SIGNIFICANCE: FCV was the most frequently encountered URTD pathogen in this sample of cats; this should be noted for disinfectant choice. In cats suspected of having FHV or C. felis infection, assessment for co-infection with FCV is recommended.

Tumour necrosis factor-mediated macrophage activation in the target organ is critical for clinical manifestation of uveitis.

Clinically available anti-tumour necrosis factor (TNF) biologics, which inhibit both soluble (sTNF) and transmembrane forms (tmTNF) of TNF, eliminating all TNF signalling, have successfully treated autoimmune diseases including uveitis. These have potentially serious side effects such as reactivation of latent Mycobacterium tuberculosis and, therefore, more specific inhibition of TNF signalling pathways may maintain clinical efficacy while reducing adverse effects. To determine the effects of specific pharmacological inhibition of sTNF on macrophage activation and migration, we used a mouse model of uveitis (experimental autoimmune uveoretinitis; EAU). We show that selective inhibition of sTNF is sufficient to suppress EAU by limiting inflammatory CD11b(+) macrophages and CD4(+) T cell migration into the eye. However, inhibition of both sTNF and tmTNF is required to inhibit interferon-γ-induced chemokine receptor 2, CD40, major histocompatibility complex class II and nitric oxide (NO) up-regulation, and signalling via tmTNF is sufficient to mediate tissue damage. In confirmation, intravitreal inhibition of sTNF alone did not suppress disease, and inflammatory cells that migrated into the eye were activated, generating NO, thus causing structural damage to the retina. In contrast, intravitreal inhibition of both sTNF and tmTNF suppressed macrophage activation and therefore disease. We conclude that sTNF is required for inflammatory cell infiltration into target tissue, but at the tissue site inhibition of both sTNF and tmTNF is required to inhibit macrophage activation and to protect from tissue damage.

Detection of allelic variants of the canine IGHA gene by fluorescence resonance energy transfer melting temperature examination.

The fluorescence resonance energy transfer (FRET) dual hybridisation probe system has been used for the detection of the accumulation of target DNA during real-time PCR and for the identification of nucleotide polymorphisms through examination of melt curves. This system involves the use of two oligonucleotide probes which are located close to each other and are complementary to an internal segment of a target DNA of interest. Four allelic variants of the gene encoding the hinge region of the immunoglobulin A (IgA) heavy chain (IGHA) have been so far identified in the dog and this variability is due to a combination of single nucleotide polymorphisms and insertion/deletion of nucleic acid motifs. An individual dog may be homozygous or heterozygous for these allelic variants. The purpose of this study was to develop a FRET-based dual probe melting temperature assay to identify the alleles present within an individual dog and to use this assay to determine the frequency of the four allelic variants in different breeds within the canine population. A single pair of oligonucleotide probes were designed that were able to discriminate between the four allelic variants in both homozygous and heterozygous individuals. The genotype of 96 DNA samples obtained from various purebreeds of dogs was determined using this FRET assay. The frequency of each allele differed between the breed groups. The results of this study indicate that it is possible to distinguish relatively complex gene polymorphisms using a single set of oligonucleotide probes. Furthermore, any future comparison of IGHA genotypes between normal and diseased dog populations must take into account the breed variation in allelic frequency.

Factors associated with upper respiratory tract disease caused by feline herpesvirus, feline calicivirus, Chlamydophila felis and Bordetella bronchiseptica in cats: experience from 218 European catteries.

A full history of the management practices and the prevalence of upper respiratory tract disease (URTD) at 218 rescue shelters, breeding establishments and private households with five or more cats was recorded. Oropharyngeal and conjunctival swabs and blood samples were taken from 1748 cats. The prevalences of feline herpesvirus (FHV), feline calicivirus (FCV), Chlamydophila felis and Bordetella bronchiseptica were determined by PCR on swab samples. An ELISA was applied to determine the prevalence of antibodies to B. bronchiseptica. The rates of detection by PCR of each pathogen in the cats in catteries with and without ongoing URTD were, respectively, FHV 16 per cent and 8 per cent; FCV 47 per cent and 29 per cent; C. felis 10 per cent and 3 per cent; and B. bronchiseptica 5 per cent and 1.3 per cent; the seroprevalences of B. bronchiseptica were 61 per cent and 41 per cent, respectively. There was evidence that FHV, FCV and B. bronchiseptica played a role in URTD. The risk factors associated with the disease were less than excellent hygiene, contact with dogs with URTD, and larger numbers of cats in the cattery or household.