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).

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.

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.

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 adenovirus survey of poultry flocks during the growing and laying periods.

Chicken adenoviruses were isolated from asymptomatic chickens on each of 7 farms tested; a majority of them induced cytopathology by the second serial passage. Although adenoviruses were isolated from chickens ranging in age from 8 to 34 weeks, the highest isolation rate was from those 8 to 14 weeks. Eight serotypes (1, 2, 4, 5, 6, 7, 8, and 9) were identified in a relatively small geographic area; serotypes 1, 4, 7, and 9 were isolated most frequently. Multiple serotypes were found on 6 of 7 farms, with 1 farm having 4 serotypes identified. Repeat isolations of the same serotypes were noted on 2 farms. The pattern of virus isolations was generally related to age but varied according to farm. Although new serotypes kept appearing, even after birds came into lay, no clinical problems were associated with them. The incidence of precipitin reactors tended to be low (10-40%) in immature birds but reached 80% or more after sexual maturity. The "antiserum pool" modification of the VN test was found to be accurate and less cumbersome than the conventional procedure for typing isolants.

Use of counter immunoelectrophoresis in detection of antibodies to tickborne fever.

A micromethod using the counter immunoelectrophoresis technique for the detection of antibodies to Cytoecetes phagocytophila, the causative agent of tickborne fever (TBF) is described. Antibodies were first detected nine to 11 days after experimental infection of lambs with TBF and persisted for six to 10 weeks after infection. The test was also applied to approximately 440 field samples of ovine sera collected from tick infested farms in Scotland and the north of England, 16 per cent of which proved positive and showed a marked seasonal variation.

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.

Control of ovine gastrointestinal helminthiasis by the use of 'clean' grazing and strategic dosing in the field.

Despite the widespread adoption of clean grazing systems in lowland sheep flocks, detailed parasitological investigations had not previously been carried out on such flocks. A trial was therefore conducted on two commercial flocks: a traditional permanent pasture flock (A) and one operating a system of clean grazing (B), and on an East of Scotland College flock (C) which had operated a clean grazing system for eight years. Ewe and lamb worm egg output, pasture larval levels and lamb liveweight gains were monitored and tracer lambs were grazed during July and August on each farm. Under clean grazing conditions on farm C all parasitological parameters were lower than on both commercial farms. However, in the commercial flocks comparable contamination was evident from midsummer onwards and tracer lambs grazed during August on farm B had significantly greater worm burdens than on the other two farms. The differences observed between the flocks were thought to be due to greater residual contamination by overwintered larvae in both commercial flocks while the higher worm burdens in August on farm B probably resulted partly from incomplete control of the periparturient rise in ewe faecal egg output and partly to autoinfection of the lamb crop. It was concluded that farm C grazing was the cleanest. Considerable contamination was present on farm A while farm B occupied an intermediate position which resulted in considerable worm burdens in lambs grazing during the latter part of the season.

Failure to protect calves against Taenia saginata using antigens prepared from in vitro cultivation of the larval stage.

Calves were vaccinated intramuscularly against the tapeworm Taenia saginata using excretory/secretory (ES) antigens from short and long term periods of in vitro cultivation of the larval stage of the parasite, four weeks before challenge with 5000 T saginata onchospheres. Neither immunisation regime employed afforded significant protection against challenge. It was considered that this may have been due to a reduction in concentration of, or detrimental effects to, potential immunogens during vaccine production. Elucidation of the nature of the protective ES antigens necessary for standardization of the technique has yet to be achieved in helminths.

Stimulation of resistance to Fasciola hepatica infection in sheep by a regime involving the use of the immunomodulatory compound L tetramisole (levamisole).

The effect of prior nematode and cestode infection in sheep on the course of experimental Fasciola hepatica was studied. The cross immunising properties of these parasites per se and the modification of any protective effect conferred by the immunomodulatory compound L tetramisole (levamisole) were investigated. It was recorded that no protection was conferred on sheep against F hepatica infection by virtue of prior infection with any helminth species per se, including Cysticercus tenuicollis. However, a degree of immunity to F hepatica was recorded, for only the second time, in sheep primed with helminth infections before treatment with levamisole. This is the first demonstration of a beneficial effect conferred by levamisole by virtue of its immunomodulatory properties in ruminants infected with any helminth species. Resistance was shown by a 47 per cent reduction in flukes recovered from sheep treated in this way (P less than 0.05).

Epidemiology of Nematodirus battus infection in eastern Scotland.

A field investigation was carried out from 1981 to 1983 on the prevalence of Nematodirus battus under different systems of lowland sheep management. Pasture larval counts, ewe and lamb worm egg counts, and tracer lamb worm counts were carried out. As expected, contamination was generally greater on permanent pasture than on new leys as measured by pasture larval counts and lamb worm egg counts. However significant contamination was also recorded on young grass fields for which alternate grazing with young calves may have been partly responsible. It is suggested that the 1983 hatch was delayed because of a drop in soil temperature in late March which may have increased subsequent scour problems involving N battus seen in May.

Comparative study of gastrointestinal helminthiasis in sheep on 'clean' grazing and permanent pasture under field conditions.

An investigation of sources of helminth infection was carried out on three flocks: a traditional permanent pasture flock (A), one operating a 'clean' grazing system (B), and an East of Scotland College flock (C) which had operated a clean grazing system for nine years. Ewe and lamb worm egg output and pasture larval levels were recorded and tracer lambs were grazed during July and August on each farm. Considerable contamination was present on farm B fields compared with farms A and C, which resulted in higher worm burdens in late summer in farm B tracer lambs and lower weight gains. The main source of this infection was thought to be ewe periparturient egg output, as 21 per cent of ewes had positive worm egg counts over the lambing period. Differences in management practices between farms B and C, eg, earlier stocking of farm B fields, were also considered contributory factors.

Successful passive transfer of resistance to Fasciola hepatica infection in rats by immune serum and transfer factor.

Resistance to Fasciola hepatica was shown by a 64 per cent reduction in fluke recovery compared with control rats was recorded in rats inoculated with serum from sheep experimentally infected with F hepatica. A comparable reduction (55.6 per cent) was obtained using transfer factor prepared from lysed leucocytes of infected rats. No significant reduction was obtained using transfer factor prepared from sheep or calves.

Assessment of an oxfendazole pulsed release bolus for control of parasitic gastroenteritis in calves in a rotational grazing system.

A group of 71 Friesian bullocks, aged six to nine months, vaccinated against lungworm, were randomly allocated on a liveweight basis to two groups of 40 and 31 animals. At turn-out each calf in the group of 40 calves was dosed orally with a pulsed release bolus designed to deliver five doses of oxfendazole at regular intervals during a period of up to 130 days, the first dose being released about 21 days after administration. The group treated with the bolus grazed 2.4 ha and the control group grazed 3.6 ha of permanent pasture for six weeks before having additional access to similar areas of silage aftermath. The control group was treated 99 days after turn-out and when they were housed with fenbendazole (7.5 mg/kg). Faecal worm egg counts, plasma pepsinogen activities, pasture larval counts and liveweights were recorded fortnightly. Significant reductions in worm egg counts and plasma pepsinogen activities were recorded in the calves dosed with the pulsed release bolus together with significant improvements in the liveweight of younger calves compared with control animals. Pasture larval counts were lower in the fields grazed by animals treated with the bolus.

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.