Infectious canine hepatitis in red foxes (Vulpes vulpes) in wildlife rescue centres in the UK.

Outbreaks of infectious canine hepatitis are described in red foxes ( ITALIC! Vulpes vulpes) at two wildlife rescue centres in the UK. Disease occurred in two-month-old to four-month-old juvenile foxes, which were held in small enclosures in groups of three to eight animals. The foxes died or were euthanased after a short clinical course, sometimes including neurological signs and jaundice, with a high case fatality rate. Four red foxes submitted for postmortem examination had enlarged, congested livers, with rounded borders and mild accentuation of the lobular pattern. On histological examination, there was random, multifocal to massive hepatic necrosis, along with multifocal vasculitis in the central nervous system (CNS) and mild, multifocal glomerulonephritis. Intranuclear inclusion bodies, typical of canine adenovirus type 1 (CAV-1) infection, were present in hepatocytes, vascular endothelial cells in the CNS, renal glomeruli and renal tubular epithelial cells. CAV-1 was detected in tissues from affected foxes by PCR and sequencing. Congregation of juvenile foxes in wildlife rescue centres is likely to be a risk factor for transmission of CAV-1. Preventive measures in wildlife centres should be implemented to prevent the spread of the virus among conspecifics and to other susceptible species.

Localization and functional characterization of pulmonary bovine odorant-binding protein.

Bovine odorant-binding protein (OBP) may function in olfaction and defense against oxidative injury, but its role in inflammation and defense against bacterial infection has not been investigated. Expression of OBP was discovered in the bovine lung and found to undergo changes in abundance during glucocorticoid administration and stress. OBP was localized to nasal, tracheal, and bronchial mucosal glands with immunohistochemistry, with faint expression in airway surface epithelium and none in bronchioles or alveoli. Two isoforms of OBP were identified, appearing to be differentially regulated during lipopolysaccharide-induced pulmonary inflammation, but differences between these isoforms were not revealed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Functional studies showed no effect of OBP on in vitro growth of Escherichia coli or Mannheimia haemolytica under iron-replete or iron-depleted conditions, nor did OBP opsonize bacteria for an enhanced neutrophil oxidative burst. However, OBP did reduce the ability of supernatants from lipopolysaccharide-stimulated macrophages to induce neutrophil chemotaxis. These findings indicate that OBP may inhibit neutrophil recruitment by inflammatory mediators, and they suggest an ability to bind macrophage-derived inflammatory mediators within the airways.

Impairment of innate immune responses of airway epithelium by infection with bovine viral diarrhea virus.

Bovine viral diarrhea virus (BVDV) infection is an important risk factor for development of shipping fever pneumonia in feedlot cattle, and infects but does not cause morphologic evidence of damage to airway epithelial cells. We hypothesized that BVDV predisposes to bacterial pneumonia by impairing innate immune responses in airway epithelial cells. Primary cultures of bovine tracheal epithelial cells were infected with BVDV for 48 h, then stimulated with LPS for 16 h. Expression of tracheal antimicrobial peptide (TAP) and lingual antimicrobial peptide (LAP) mRNA was measured by quantitative RT-PCR, and lactoferrin concentrations were measured in culture supernatant by ELISA. BVDV infection had no detectable effect on the constitutive expression of TAP and LAP mRNA or lactoferrin concentration in culture supernatant. LPS treatment provoked a significant increase in TAP mRNA expression and lactoferrin concentration in the culture supernatant (p<0.01), and these effects were significantly (p<0.02, p<0.01) abrogated by prior infection of the tracheal epithelial cells with the type 2 ncp-BVDV isolate. In contrast, infection with the type 1 ncp-BVDV isolate had no effect on TAP mRNA expression or lactoferrin secretion. LPS treatment induced a significant (p<0.001) upregulation of LAP mRNA expression, which was not significantly affected by prior infection with BVDV. These data indicate that infection with a type 2 BVDV isolate inhibits the LPS-induced upregulation of TAP mRNA expression and lactoferrin secretion by tracheal epithelial cells, suggesting a novel mechanism by which this virus abrogates respiratory innate immune responses and predisposes to bacterial pneumonia in cattle.

A small scale survey of ivermectin resistance in sheep nematodes using the faecal egg count reduction test on samples collected from Scottish sheep.

Thirty-eight sheep flocks, predominantly from the south/central Scotland, were examined using a faecal egg count reduction test (FECRT) for the presence of ivermectin (IVM) resistant nematodes. Efficacies of less than 95%, 14-17 days post-treatment, were identified in 6 of 17 naturally grazing flocks where pre-treatment faecal egg counts were in excess of 150 eggs per gram. Efficacies on these IVM resistant farms ranged from 66 to 92%. One other suspected cases of IVM resistance was also identified in returned material. The larvae detected in post-treatment coprocultures from resistant flocks were from the genera Teladorsagia (4 from 6) and Trichostrongylus (2 from 6).

CD45 modulation of CXCR1 and CXCR2 in human polymorphonuclear leukocytes.

All leukocytes express the cell surface glycoprotein CD45, which has intrinsic intracellular protein tyrosine phosphatase activity. CD45 is known to play a regulatory role in activation-induced signaling in lymphocytes; however, little is known of its role in non-lymphoid leukocytes. Therefore, we examined the potential effect of CD45 on chemokine-induced signaling in human neutrophils (polymorphonuclear cells, PMN). Treating isolated PMN for 2 h with an anti-CD45RB antibody (Bra11) down-modulated expression of the chemokine receptors CXCR1 and CXCR2 to 44 +/- 10% and 47 +/- 9% of their respective controls. The tyrosine kinase inhibitors genistein and herbimycin A significantly inhibited the Bra11-induced down-modulation of CXCR1 and CXCR2. Furthermore, Bra11-treated PMN were functionally inhibited in their capacity to exhibit IL-8-induced transient intracellular Ca2+ increases. Selected targeting of CXC receptors is indicated by the fact that N-formyl-Met-Leu-Phe (fMLP) receptor expression and function were not lost following Bra11 treatment. The effect of Bra11 on IL-8-mediated function and receptor expression was paralleled by decreased tyrosine phosphorylation of a 54- to 60-kDa protein. These findings indicate that CD45 can act to modulate PMN responses to chemokines; thus agents regulating CD45 can potentially modulate leukocyte traffic and may represent a novel therapeutic approach towards the treatment of inflammatory diseases.

beta-arrestins regulate interleukin-8-induced CXCR1 internalization.

The functional role of neutrophils during acute inflammatory responses is regulated by two high affinity interleukin-8 receptors (CXCR1 and CXCR2) that are rapidly desensitized and internalized upon binding their cognate chemokine ligands. The efficient re-expression of CXCR1 on the surface of neutrophils following agonist-induced internalization suggests that CXCR1 surface receptor turnover may involve regulatory pathways and intracellular factors similar to those regulating beta2-adrenergic receptor internalization and re-expression. To examine the internalization pathway utilized by ligand-activated CXCR1, a CXCR1-GFP construct was transiently expressed in two different cell lines, HEK 293 and RBL-2H3 cells. While interleukin-8 stimulation promoted CXCR1 sequestration in RBL-2H3 cells, receptor internalization in HEK 293 cells required co-expression of G protein-coupled receptor kinase 2 and beta-arrestin proteins. The importance of beta-arrestins in CXCR1 internalization was confirmed by the ability of a dominant negative beta-arrestin 1-V53D mutant to block internalization of CXCR1 in RBL-2H3 cells. A role for dynamin was also demonstrated by the lack of CXCR1 internalization in dynamin I-K44A dominant negative mutant-transfected RBL-2H3 cells. Agonist-promoted co-localization of transferrin and CXCR1-GFP in endosomes of RBL-2H3 cells confirmed that receptor internalization occurs via clathrin-coated vesicles. Our data provides a direct link between agonist-induced internalization of CXCR1 and a requirement for G protein-coupled receptor kinase 2, beta-arrestins, and dynamin during this process.

Tumor-promoting effect of urinary epidermal growth factor in rat urinary bladder carcinogenesis.

We previously demonstrated that the specific component of rat urine designated as Fraction I (Fr.I), which has been known to enhance carcinogenesis in the rat urinary bladder, contains epidermal growth factor (EGF) and transferrin (TF). The present study was designed to determine whether EGF or TF is responsible for the tumor-enhancing effect of Fr.I. The heterotopically transplanted rat urinary bladder (HTB), which has been developed in our laboratory, was used for the study. Fr.I was prepared from normal rat urine by a method published previously. Fr.I deficient in EGF or TF was prepared by passing this fraction through an Affi-Gel Hz column coupled with anti-rat EGF or TF antibodies, respectively. EGF and TF eluted from the column (designated as eluted EGF and eluted TF) were also tested for tumor-enhancing activity. Fr.I passed through the column coupled with nonimmune rabbit IgG served as control (Fr.I column control). After initiation of carcinogenesis in HTBs by instillation of a single dose of 0.25 mg of N-methyl-N-nitrosourea, test materials were administered into these HTBs once a week for 30 weeks. The results showed that removal of EGF significantly reduced the tumor-enhancing effect of Fr.I (P less than 0.001 as compared to that of the Fr.I column control) and that eluted EGF by itself significantly enhanced the carcinogenesis as compared to that of the vehicle control (P less than 0.006). Removal of TF from Fr.I also reduced the tumor-enhancing effect of Fr.I (P less than 0.01). However, removal of both EGF and TF from Fr.I did not enhance the inhibitory effect demonstrated by the Fr.I which was deficient in EGF. Likewise, combined use of TF and EGF did not exceed the tumor-promoting effect of EGF. The results indicate that EGF in Fr.I may play a significant role in the promotion of bladder carcinogenesis by urine.

Experimental production of tick pyaemia.

Lambs aged 2 weeks were inoculated with a tick-borne fever (TBF) stabilate on Day 0 and Staphylococcus aureus-contaminated ticks were applied on Day 5. Tick pyaemia was produced experimentally for the first time using Ixodes ricinus as a mechanical vector of S. aureus. Lambs aged 18 weeks were rechallenged with a homologous strain of TBF, and S. aureus-infected ticks applied 5 days later. No significant changes were noted at post-mortem examination.

An electron microscopic study of Cytoecetes phagocytophila infection in Ixodes ricinus.

Tick-borne fever, caused by a rickettsia-like organism, Cytoecetes phagocytophila, is transmitted by the sheep tick Ixodes ricinus. An electron microscopic technique was developed to examine I ricinus for C phagocytophila infection. Infected and uninfected ticks were obtained from a laboratory maintained tick culture. All stages of I ricinus collected from one field site were examined; 44 per cent of nymphae and 32 per cent of adults were infected with C phagocytophila, but larvae were uninfected. This supports the previously held theory of transtadial, but not transovarial transmission of tick-borne fever.

Acute nephropathy in young lambs.

Acute renal failure was diagnosed by clinical, necropsy and histological criteria in 39 flocks (20 low ground, 13 hill and six marginal upland) in areas served by six veterinary investigation centres. Forty-eight lambs of 12 different breeds or crosses were investigated. The mean age of affected lambs was 38 days (range seven to 84 days); 21 lambs (44 per cent) were aged seven to 28 days, while only eight (17 per cent) were older than two months. Mortality in clinically affected lambs was almost 100 per cent, with no response to various treatments. Histological examination showed that 40 lambs (83 per cent) had nephrosis, while the rest had toxic tubular necrosis, interstitial nephritis or tubular damage associated with oxalate crystal deposits. Only about half of the lambs had any evidence of enteric infections or enteropathy. Acutely ill lambs had azotaemia, haemoconcentration and proteinuria; some lambs had glycosuria or haematuria. Samples of plasma from 22 lambs with nephrosis were compared with similar samples from 82 incontact but asymptomatic lambs. The clinically affected group had significantly elevated plasma urea, creatinine, total protein, globulin, phosphorus and chloride concentrations and significantly reduced plasma calcium concentrations compared with healthy lambs. Affected lambs had a significant reduction also in the calcium:phosphorus ratio. No significant differences between groups was found in plasma concentrations of albumin, glucose, lactate, glycerol, creatine kinase, alkaline phosphatase, sodium, potassium or magnesium.