Neuraminidase production by Erysipelothrix rhusiopathiae

In order to characterise neuraminidase activity by Erysipelothrix, 85 isolates of Erysipelothrix spp. from a variety of sources including human clinical, marine and terrestrial animals, and the environment were investigated for neuraminidase production. Neuraminidase activity was detected by a peanut lectin haemagglutination method. The effects of media, incubation conditions and pH on the production and activity of neuraminidase were also investigated. Enzyme activity was detected only in the supernatants of the isolates of Erysipelothrix rhusiopathiae which had been incubated in cooked meat broth and Todd Hewitt broth supplemented with horse serum after 16 and 36 h incubation at 37 degrees C. The maximum titres were reached at 40 h in cooked meat broth and 56 h in Todd Hewitt broth supplemented with horse serum. All 58 isolates and the type strain (ATCC 19414) of E. rhusiopathiae produced detectable neuraminidase activity with titres between 10 and 320. The optimal pH for the enzyme activity varied among the isolates with a pH between 6.0 and 7.0 covering the highest enzyme activity of the most. There was no statistically significant difference in the level of neuraminidase activity between isolates from different sources (p > 0.05). Neuraminidase activity was not detected in the non-pathogenic Erysipelothrix spp. such as E. tonsillarum. Neuraminidase was detected only in E. rhusiopathiae suggesting its possible role as a virulence factor. Enzyme production and activity were medium and pH dependent. The peanut lectin haemagglutination assay is a simple, rapid and sensitive method and is particularly useful for the analysis of multiple samples.     

Characterization of a wild-type strain of Francisella tularensis isolated from a cat.

Francisella tularensis type A is the primary cause of tularemia in animals and humans in North America. The majority of research on F. tularensis has been done with the attenuated live vaccine strain (LVS), which is a type B, but very few wild-type F. tularensis strains have been characterized. A gram-negative coccobacillus that was isolated in pure culture from the lungs of a cat that died after being lost for 5 days was received for identification at the Virginia-Maryland Regional College of Veterinary Medicine Teaching hospital. The isolate (strain TI0902) was not identified (or was misidentified) by commercial identification systems; however, it was identified as F. tularensis subspecies tularensis (type A) by sequencing a portion of the 16S ribosomal RNA gene. Furthermore, repetitive extragenic palindromic sequences-polymerase chain reaction amplified a 4-kb DNA fragment from TI0902 that was characteristic of F. tularensis type A but not type B. The electrophoretic profile of the lipopolysaccharide of strain TI0902 was identical to that of the LVS by Western blotting with antiserum to LVS. The protein-enriched outer membrane of strain TI0902 contained 6-8 proteins, which were similar in molecular size to those from the LVS. Electron microscopy of negatively stained and alcian blue-stained LVS and TI0902 cells showed that both strains were coccobacillary in shape and may be encapsulated. However, after mouse challenge, the TI0902 strain was clearly more virulent than the LVS strain. Results of this study indicate that the genotype and phenotype of wild-type F. tularensis type A strain TI0902 is similar, but not identical, to that of the LVS strain. Further studies will help determine whether pathogenesis and host-pathogen interactions are also similar between the 2 strains.     

Epidemiological investigations of contagious caprine pleuropneumonia in selected districts of Borana zone,Southern Oromia,Ethiopia

Tropical Animal Health and Production - From November 2016 to April 2017, a cross-sectional study to determine the sero-prevalence of contagious caprine pleuropneumonia (CCPP) and to investigate...     

Humoral immune response to a recombinant hemoplasma antigen in experimental 'Candidatus Mycoplasma turicensis' infection

'Candidatus Mycoplasma turicensis' is a feline hemoplasma species that was isolated in a cat with hemolytic anemia. PCR has been widely used to investigate and diagnose 'Candidatus Mycoplasma turicensis' infection, but so far, little is known about the humoral immune response in infected cats. Recently, enzyme-linked immunosorbent assays (ELISA) were developed to monitor anti-feline hemoplasma antibodies. The aim of the present study was to investigate the humoral immune response in cats experimentally infected with 'Candidatus Mycoplasma turicensis' and to monitor the influence of the pre-administration of methylprednisolone and subsequent antibiotic treatment. Serum and plasma samples from 15 specified pathogen-free cats infected with 'Candidatus Mycoplasma turicensis' were analyzed by ELISA. Seroconversion was demonstrated in all cats, and the antibodies remained detectable until the end of the study (up to 100 weeks post-exposure). In some cats, the ELISA seemed more sensitive and better able to demonstrate exposure to 'Candidatus Mycoplasma turicensis' than PCR. The peak antibody level occurred after the peak of the bacterial blood loads. The methylprednisolone administrations were associated with increased antibody levels, while antibiotic treatment, particularly with doxycycline, resulted in a decrease in antibody levels. Additionally, preliminary data indicated that three of four seropositive cats were protected from bacteremia after a subsequent challenge. In conclusion, the ELISA was found to be a useful tool to investigate the humoral immune response in hemoplasma-infected cats and a desirable addition to PCR to study the pathogenesis of hemoplasma infections.     

Cataracts are not associated with retinal detachment in the Bichon Frise in the UK--a retrospective study of preoperative findings and outcomes in 40 eyes

Objective The aim of this study was to evaluate whether the Bichon Frise population in the UK is at the same risk of developing retinal detachment in association with cataract formation and following phacoemulsification as described in reports from the USA. Procedures The medical records of Bichon Frises which were presented for cataract assessment and of those which were treated with phacoemulsification at Willows Referral Service between 1997 and 2009 were reviewed. Results Forty eyes (26 dogs) with unilateral or bilateral cataracts were included in the study. There was no evidence of retinal detachment associated with the cataracts at initial presentation. Phacoemulsification was performed on 34 eyes (20 dogs). Clinically evident lens‐induced uveitis was treated preoperatively in 17/34 eyes. Artificial lens implantation was carried out in 30/34 eyes; automated anterior vitrectomy was performed in 7/34 eyes. The mean follow‐up time was 16.6 months (range 1.5–73 months). At the last re‐examination, 31/34 eyes (91.2%) were visual. Three eyes (8.8%) were blind – two (in the same dog) because of presumptive bilateral optic nerve disease and one because of uveitis and secondary glaucoma. There was no evidence of retinal detachment following phacoemulsification in any of the 34 eyes. Conclusion This study suggests that the Bichon Frise population in the UK does not appear to have a predisposition for retinal detachment in association with cataract formation or following cataract surgery. Prophylactic random transscleral laser retinopexy or transscleral cryopexy cannot therefore be routinely recommended for Bichon Frises with cataracts in the UK.     

Macrophakia in three cats

This report describes three cases of bilateral macrophakia in 3-, 5-, and 9-year-old cats, respectively. All cats were presented because of visual deficits. Ophthalmic examination revealed macrophakia (the vitreous was replaced by the lens) and retinal changes (tapetal hyper-reflectivity, attenuation of retinal vessels, and retinal folds) in all cats. In addition, bilateral subconjunctival orbital fat prolapse in one cat and microphthalmos in another cat were present. To confirm the ophthalmologic diagnosis of macrophakia, gross pathology examination in one cat and ultrasound examination in another cat were performed.     

Evaluation of a point-of-care test for canine C-reactive protein

Background: In veterinary medicine, there is increasing interest in measuring C‐reactive protein (CRP) as a tool for diagnosis and monitoring of inflammatory diseases. Reported CRP concentrations for healthy dogs have ranged from 0 to 8.9 mg/L. Objectives: The aims of this study were to evaluate a canine‐specific point‐of‐care (POC) lateral flow immunoassay for qualitative CRP measurement in healthy and diseased dogs and to compare results with those obtained by a quantitative ELISA. Methods: Blood samples from 73 client‐owned dogs were available for testing: 16 healthy dogs and 57 dogs with a variety of infectious, inflammatory, or neoplastic diseases. CRP was measured in heparinized whole blood samples and serum with the TECOmedical Dog CRP‐visual POC test. A red line develops in the POC device if CRP is ≥5 mg/L, and results are scored as negative or positive. An ELISA validated previously for canine serum was used as the reference method. Results: For all dogs, serum CRP concentrations measured by the ELISA ranged from 0.1 to ≥350 mg/L (median=38 mg/L). Percentages of the CRP POC test results that agreed with the ELISA results were 98.6% for whole blood and 97.3% for serum samples. For serum samples, sensitivity of the POC test was 96.4% and specificity was 81.3%. For whole blood, sensitivity was 94.7% and specificity was 93.8%. Conclusions: The POC test had very good agreement with the ELISA test and had high sensitivity and specificity; therefore, it can be used as a qualitative test to screen for increases in CRP concentrations.     

The innate antiviral immune system of the cat: molecular tools for the measurement of its state of activation

The innate immune system plays a central role in host defence against viruses. While many studies portray mechanisms in early antiviral immune responses of humans and mice, much remains to be discovered about these mechanisms in the cat. With the objective of shedding light on early host-virus interactions in felids, we have developed 12 real-time TaqMan(?) qPCR systems for feline genes relevant to innate responses to viral infection, including those encoding for various IFNα and IFNω subtypes, IFNβ, intracellular antiviral factor Mx, NK cell stimulator IL-15 and effectors perforin and granzyme B, as well as Toll-like receptors (TLRs) 3 and 8. Using these newly developed assays and others previously described, we measured the relative expression of selected markers at early time points after viral infection in vitro and in vivo. Feline embryonic fibroblasts (FEA) inoculated with feline leukemia virus (FeLV) indicated peak levels of IFNα, IFNβ and Mx expression already 6h after infection. In contrast, Crandell-Rees feline kidney (CrFK) cells inoculated with feline herpes virus (FHV) responded to infection with high levels of IFNα and IFNβ only after 24h, and no induction of Mx could be detected. In feline PBMCs challenged in vitro with feline immunodeficiency virus (FIV), maximal expression levels of IFNα, β and ω subtype genes as well as IL-15 and TLRs 3, 7 and 8 were measured between 12 and 24h after infection, whereas expression levels of proinflammatory cytokine gene IL-6 were consistently downregulated until 48h post inoculation. A marginal upregulation of granzyme B was also observed within 3h after infection. In an in vivo experiment, cats challenged with FIV exhibited a 2.4-fold increase in IFNα expression in blood 1 week post infection. We furthermore demonstrate the possibility of stimulating feline immune cells in vitro with various immune response modifiers (IRMs) already known for their immunostimulatory properties in mice and humans, namely Poly IC, Resiquimod (R-848) and dSLIM?, a synthetic oligonucleotide containing several unmethylated CpG motifs. Stimulation of feline PBMCs with dSLIM? and R-848 effectively enhanced expression of IFNα within 12h by factors of 6 and 12, respectively, and Poly IC induced an increase in Mx mRNA expression of 28-fold. Altogether, we describe new molecular tools and their successful use for the characterization of innate immune responses against viruses in the cat and provide evidence that feline cells can be stimulated by synthetic molecules to enhance their antiviral defence mechanisms.